GIS 201 Final Notes PDF

Week 1 Introduction to Geomatic Techniques in Natural Resource Management Basic Definitions  Geomatics: a modern discipline that integrates the tasks of gathering, storing, processing, modeling, analyzing, and delivering spatially referenced data....

Week 1 Introduction to Geomatic Techniques in Natural Resource Management Basic Definitions  Geomatics: a modern discipline that integrates the tasks of gathering, storing, processing, modeling, analyzing, and delivering spatially referenced data.  The term geomatics was created at Laval University in Canada in 1982 (Michel Paradis).  "Geo" refers to Earth / "matics" comes from informatics.  Data vs. Information in Geomatics:  Data: Raw measurements or observations.  Information: Processed and interpreted data. Scope of Geomatics Graphical or numerical representation of Earth's shape and Cartography dimension and its natural and artificial details. Geodesy determine the shape and size of the Earth. Photogrammetry position and shapes of objects from photographic images. Global Positioning Systems provides 3D positioning of objects of fixed or moving objects, in in (GPS) real-time. Remote Sensing Remotely acquires territorial and environmental spatial data Geographic Information manage, analyze, and visualize spatially referenced data. Systems (GIS) measure and describe the physical features of oceans, seas, coastal Hydrography areas, lakes, and rivers. Topography measure and represent details of the Earth’s surface. Geomatics Today  Technological advancements have revolutionized geomatics, enabling better environmental management.  Many current Earth-observing satellites collect vast amounts of data about Earth's systems.  Cloud computing and improved hardware allow near real-time processing of large datasets.  Geomatics applications have expanded beyond Earth to other planets.  The field continues to evolve, with new applications and technologies emerging regularly. Mohamed Shawky REN R 201 – Fall Term 2024 1 Week 1 Introduction to Geomatic Techniques in Natural Resource Management Geomatics Applications in Natural Resource Management Application Description Focus on preserving biodiversity and managing ecosystems Conservation Biology to protect species and habitats. Study and manage forest ecosystems to ensure sustainable Forest Ecology and Management use and conservation. Research sustainable agricultural practices that minimize Agriculture and the Environment environmental impact and enhance ecosystem services. Land Reclamation and Develop techniques for restoring disturbed land and water Remediation bodies to their natural state. Study soil properties and processes to improve land Environmental Soil Science management and agricultural productivity. Manage water resources and land use to balance Water and Land Resources ecological, economic, and social needs. Study wildlife populations and their habitats to inform Wildlife Management conservation and management strategies. Protected Areas and Wildland Plan and manage protected areas to conserve natural Management landscapes and biodiversity https://www.ualberta.ca/en/renewable-resources/index.html Mohamed Shawky REN R 201 – Fall Term 2024 2 Week 1 Introduction to Geomatic Techniques in Natural Resource Management Geomatics Applications in Natural Resource Management in Alberta Application Description Track environmental impacts of oil sands development Oil Sands Monitoring using remote sensing and GIS Inventory and classify wetlands to support conservation Wetland Mapping and land use planning Predict fire behavior, plan fire suppression strategies, and Forest Fire Management assess post-fire recovery Map and monitor critical habitat for woodland caribou Caribou Habitat Management conservation efforts Some Potential Career  Natural Resource Management Specialist  Environmental Geomatics Analyst  Remote Sensing Specialist for Forestry  GIS Technician for Wildlife Management  Environmental Consultant  Geospatial Solutions Developer for Resource Management  Land Reclamation Specialist  Precision Agriculture Analyst Geographic Concepts Before we can learn “GIS, it is first necessary to reconsider key geographic concepts: 1) Location is a fundamental concept in geography and GIS, referring to the position of an object on the Earth’s surface.  Locations can be defined as:  Nominal: Described by name (e.g. city names).  Absolute: Using a reference system (e.g., lat./long.). Mohamed Shawky REN R 201 – Fall Term 2024 3 Week 1 Introduction to Geomatic Techniques in Natural Resource Management  Relative: In relation to other known locations.  Locations can refer to points, features, or large areas on Earth.  GPS technology enables precise location determination.  Essential for mapping, analyzing, and relating geographic information in GIS. 2) Direction: position of something relative to another along a line.  Egocentric Direction: Uses oneself as the reference point (e.g., "to my left").  Landmark Direction: Uses known landmarks or geographic features as reference points (e.g., a city intersection or mountain range).  Standard Benchmarks for direction include:  True North: Based on Earth's rotational axis, aligning with the North and South Poles.  Magnetic North: The point where Earth's magnetic fields converge. (3) Distance: the degree of separation between locations.  Nominal: Using qualitative terms "large," "small," "near," or "far"  Absolute: Measured or calculated using standard metrics.  Various units can be used to measure distance (e.g., meter, mile, etc.). (4) Space: often described qualitatively (e.g., "empty," "public," "private") rather than measured quantitatively.  Topological Space In GIS: focuses on the relationships and connectivity between locations within a space.  How locations are related or connected.  The rules governing these geographic relationships.  It focuses on how places are linked.  Are two locations connected directly?  It cares about rules of connection.  Which paths can you take between places?  It ignores precise distances and shapes Example: a subway map:  Stations are points of interest.  Lines show connections between stations. Mohamed Shawky REN R 201 – Fall Term 2024 4 Week 1 Introduction to Geomatic Techniques in Natural Resource Management  Transfer points show where you can change lines.  The map doesn't show real distances or exact geographic layouts. Real-world Applications of Geomatics in Natural Resource Management  Please follow the below link to access the National Aeronautics and Space Administration (NASA) Scientific Visualization Studio and examine some real-world applications of geomatic techniques in natural resource management. https://svs.gsfc.nasa.gov/ Map  A map is a symbolized image of geographic reality, representing selected features or characteristics. https://link.springer.com/article/10.1007/s12518-010-0029-6  Essential Map Elements:  Title: purpose or subject of the map.  Legend: explains symbols, colors, and patterns.  Scale: relationship between distances on the map and real-world distances.  Compass Rose: geographic north.  Grid coordinates: detect location.  Labels: text identifying features, places, or regions on the map.  Inset Map: a smaller map showing the area in a broader context.  Common Analog Map Types: Topographic, Political, Geomorphic, hydrologic, soil, Landuse/landcover. Mohamed Shawky REN R 201 – Fall Term 2024 5 Week 1 Introduction to Geomatic Techniques in Natural Resource Management Historical Map: Attribution: "Map of the Marvelous Land of Oz, Drawn by Prof. Wogglebug T.E." [endpapers to L. Frank Baum's Tik-Tok of Oz, illustrated by John R. Neill, Reilly & Britton, 1914] Map Element Example:  Title  Legend  Scale  Compass Rose (Geographic N)  Grid coordinates  Labels  Inset Map Credit: Shawky et al., 2023 Mohamed Shawky REN R 201 – Fall Term 2024 6 Week 1 Introduction to Geomatic Techniques in Natural Resource Management Spatial Thinking  How we think geographically every day with mental maps and to highlight the importance of asking geographic questions.  Humans are inherently spatial organisms, and we must somehow relate to the world around us.  Mental maps are psychological tools that represent our environment and are stored in our brains.  We use mental maps to navigate, plan activities, and understand events.  Mental maps reflect our geographic knowledge and spatial awareness. https://saylordotorg.github.io/text_essentials-of-geographic-information-systems/s05-01- spatial-thinking.html  Mental maps are unique in their artistic and cartographic representations, reflecting individual creativity.  Each map is probably an imperfect representation of one’s mental map.  What we choose to include or exclude on our maps reveals our perceptions of importance and how we navigate our environment.  Comparing mental maps from different individuals can show similarities and differences in spatial thinking and organization.  Spatial reasoning encompasses skills like visualization, orientation, and understanding spatial relationships between objects or places.  Spatial thinking skills allow us to analyze geographic relationships, patterns, and processes across different scales. Mohamed Shawky REN R 201 – Fall Term 2024 7 Week 1 Introduction to Geomatic Techniques in Natural Resource Management Mental Map Practical Example Pretend a friend is visiting you from out of town for the first time. Using the whiteboard take five to ten minutes to draw a map from memory of Central Academic Building that will help your friend get around. Modified from: https://saylordotorg.github.io/text_essentials-of-geographic-information- systems/s05-01-spatial-thinking.html Useful Tips:  What will you choose to draw on your map?  What about surrounding streets, buildings, or other points of interest.  How will you draw objects on your map?  Will you use symbols, lines, and shapes?  Will you label places on your map?  Why will you choose to include certain places and features on your map but not others?  How will you decide on the scale and orientation of your map?  Do you plan to show elevation or topographical features?  Will your map focus on a specific theme (e.g., green spaces, public transportation)? Mohamed Shawky REN R 201 – Fall Term 2024 8 Week 1 Introduction to Geomatic Techniques in Natural Resource Management Take a moment to look at each map and compare the maps with the following questions:  What similarities are there on each map?  What are some of the differences?  Which places or features are illustrated on the maps?  From what you know UofA, what is included or excluded on the maps?  At what scale is the map drawn? Asking Geographic Questions  The ability to ask geographic questions is a key part of spatial thinking and geographic inquiry.  Improving spatial thinking can enhance overall geographic understanding and problem- solving capabilities.  Filling in the gaps in our mental maps (geographic knowledge) requires us to ask questions about the world where we live and how we relate to it:  Where is the nearest hospital?  How is urbanization impacting biodiversity hotspots in Alberta?  Where are the biodiversity hotspots in relation to Edmonton?  Being able to articulate questions clearly and to break them into manageable pieces are valuable skills when using and applying a GIS. Mohamed Shawky REN R 201 – Fall Term 2024 9 Week 1 Introduction to Geomatic Techniques in Natural Resource Management Concept Geographic Questions Concept Geographic Questions Where is it? What else is near it? GL Why is it here or there? GA What else occurs with it? How much of it is here or there? What is absent in its presence? Is it distributed locally or globally? Has it always been here? How has it changed over time and GD Is it spatially clustered or dispersed? GC space? What causes its diffusion or Where are the boundaries? contraction? Is it linked to something else? GI What is the nature of this association? How much interaction occurs between the locations? G = Geographic, L= location, D = distribution, I = interaction, A = association, C = change. Practical Exercise: Apply the key geographic questions about location, distribution, association, interaction, and change to evaluate real-world environmental problems related to global warming, oil sands development, biodiversity (e.g., species distribution modeling, invasive species management, urban biodiversity management), and wildfires in Alberta. Please make sure to solve this exercise in table format. Global Aspect Question Biodiversity Aspect Question warming Where is it? Why is it here or there? GL How much of it is here or there? Mohamed Shawky REN R 201 – Fall Term 2024 10 Week 1 Introduction to Geomatic Techniques in Natural Resource Management Scale  Cartographic or representational scale is based on the ratio between the extent of the representation and that which it represents. Example: 1:100,000 cartographic map; 1 cm on the map represents 100,000 cm in reality.  Problem Scale (Spatial Extent): Geographers study phenomena at various scales and often use the term scale to help define their research interests. It representsrelative size of the space covered by a process or phenomena. Problems like global warming, this refers to the geographic area affected, which in this case would be global or worldwide in scale  Key differences:  Cartographic scale relates to map representation ratios  Cartographic scales use ratios/fractions, while problem scales use descriptive terms (e.g. local, regional, global).  Problem scale relates to the real-world geographic extent of an issue Mohamed Shawky REN R 201 – Fall Term 2024 11 Week 1 Introduction to Geomatic Techniques in Natural Resource Management References Geomatics for Environmental Management: An Open Textbook for Students and Practitioners (opengeomatics.ca). https://www.opengeomatics.ca/index.html Introduction – Introduction to Geomatics (usask.ca), https://openpress.usask.ca/introgeomatics/front-matter/introduction/ Essentials of Geographic Information Systems - Table of Contents (saylordotorg.github.io). https://saylordotorg.github.io/text_essentials-of-geographic-information-systems/index.html Gomarasca, M.A. Basics of geomatics. Appl Geomat 2, 137–146 (2010). https://doi.org/10.1007/s12518-010-0029-6. Acker, J. G., & Leptoukh, G. (2007). Online Analysis Enhances Use of NASA Earth Science Data. Eos, Transactions American Geophysical Union, 88(2), 14-17. https://doi.org/10.1029/2007EO020003 Beaudoing, H., & Rodell, M. (2020). GLDAS Noah Land Surface Model L4 monthly 0.25 x 0.25 degree V2.1. Goddard Earth Sciences Data and Information Services Center (GES DISC). Retrieved August 12, 2024, from https://doi.org/10.5067/SXAVCZFAQLNO Rodell, M., Houser, P. R., Jambor, U., Gottschalck, J., Mitchell, K., Meng, C., Arsenault, K., Cosgrove, B., Radakovich, J., Bosilovich, M., Entin, J. K., Walker, J. P., Lohmann, D., & Toll, D. (2004). The Global Land Data Assimilation System. Bulletin of the American Meteorological Society, 85(3), 381-394. https://doi.org/10.1175/BAMS-85-3-381 Shawky, M., Ahmed, M. R., Ghaderpour, E., Gupta, A., Achari, G., Dewan, A., & Hassan, Q. K. (2023). Remote sensing-derived land surface temperature trends over South Asia. Ecological Informatics, 74, 101969. https://doi.org/10.1016/j.ecoinf.2022.101969 Mohamed Shawky REN R 201 – Fall Term 2024 12 Week 2 Introduction to Geomatic Techniques in Natural Resource Management What is GIS?  Create, capture, process, manage, visualize, analyze, and interpret geospatial data.  Handle geographic locations.  Communicate about our world, particularly in the spatial dimension.  Create spatial answers (maps) to spatial questions,  provide non-spatial answers to questions  Study relationships, patterns, trends, situations, etc.  Aim to achieve smarter decisions.  The definition of GIS has changed over time in response to its expanding applications and the perspective of end users. As GIS technology and capabilities have developed alongside other technological advancements, the definition has been a "moving target “. GIS Model. Credit: https://education.nationalgeographic.org/resource/geographic- information-system-gis/ Mohamed Shawky REN R 201 – Fall Term 2024 1 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Some Key Applications of GIS  Study the distribution of populations.  Analyze physical features of the earth and natural phenomena.  Find the optimal location for an event, service, or business.  Identify geographic patterns and evaluate the distribution of features.  Measure distances and determine optimal routes or paths.  Tie together separate pieces of data to create new information  Monitor and predict environmental changes over time.  Assess and manage natural resources.  Plan and optimize urban development and infrastructure.  Support emergency response and disaster management. GIS Components GIS Components Mohamed Shawky REN R 201 – Fall Term 2024 2 Week 2 Introduction to Geomatic Techniques in Natural Resource Management (1) Data: GIS integrates geographic information with data from other sources to perform visualization and analysis. Two Major Types of Data:  Spatial data: Contains location information such as coordinates, postal codes. Represents the geographic position and shape of real-world entities. Geographic data answers "where" questions  Attribute data: Qualitative and quantitative information about the entities. May not have direct coordinates but relates to geographic features. Attribute data answers "what" questions about the object. Examples: dates, weather conditions, or other characteristics. (2) Software: Provides the functions and tools needed to input, store, manage, analyze, and display geographic data. There are a lot of different GIS software packages: Commercial ESRI’s ArcGIS. Open-Source Software: QGIS, GRASS, SAGA. (3) Hardware: GIS is implemented on hardware that includes centralized computer servers, desktop computers, and handheld devices such as smartphones. These components enable the creation, sharing, and use of geographic information across different devices and platforms. GIS software requires specific hardware components to operate effectively: CPU: Minimum 2.2 GHz. RAM: Minimum 8 GB. Graphics: Dedicated GPU with at least 4 GB VRAM recommended. Display Resolution: Minimum 1024x768; 1080p or higher recommended. Mohamed Shawky REN R 201 – Fall Term 2024 3 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Color Depth: 24-bit color depth. Operating Systems: Windows 10, 11, and various Windows Server. Additional Hardware: High-resolution monitors: Important for working with high-resolution imagery and digitizing. Specialized input devices: May include active shutter glasses, polarized glasses for stereo vision, and joysticks for 3D navigation. (4) Methods: Specific ways an organization uses GIS to solve problems and achieve its goals. These methods include the processes, procedures, and standards for working with geographic data. Why are they important? They help organizations use GIS effectively and consistently. They ensure that GIS work aligns with the organization's goals. They help maintain quality and standards in GIS work. How do they vary? Example: Forestry Company Making digital maps of forests. Keeping track of tree types and numbers. Planning where to build roads and harvest trees. Monitoring how forests grow back after harvesting. Key components of GIS methods: Activities: What specific tasks need to be done? Standards: What rules or guidelines should be followed? Quality assurance: How do we ensure the work is accurate and reliable? Mohamed Shawky REN R 201 – Fall Term 2024 4 Week 2 Introduction to Geomatic Techniques in Natural Resource Management (5) People: Role and responsibilities of GIS professionals in creating and using GIS: Identifying information needs. Defining procedures. Coding software. Building hardware. Interpreting, analyzing, and reporting results. Communicating findings through maps and reports. Nature of GIS: GIS systems are human made, not naturally occurring. They are products of human imagination and skill. Challenges: GIS systems receive both the best and worst traits of their creators. Mistakes can occur in defining procedures or identifying information needs. These mistakes can lead to incorrect conclusions. Special Considerations: GIS is a human-created tool that requires careful consideration at every stage of development and use. The quality and accuracy of GIS output depend heavily on the skills, knowledge, and integrity of the professionals involved. Users of GIS should be aware of potential biases and errors that may influence the interpretation of results. Critical thinking and awareness of potential limitations are crucial when working with or interpreting GIS data and maps. Mohamed Shawky REN R 201 – Fall Term 2024 5 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Key Concepts of Data and Information in GIS  GIS fundamentals: Data and information are the building blocks of GIS. Data: Facts, measurements, characteristics, or traits of an object of interest. Refers to raw, unprocessed facts or figures. Information: Knowledge of value obtained through the collection, interpretation, and/or analysis of data. Used to answer questions, situated within analytical frameworks, or used to obtain insights. Data vs. Information: Data becomes information when put into context or used to gain insights. Importance Geographic (Spatial) and Attribute Data in GIS:  GIS requires and integrates both types of data.  Understanding the difference is crucial for organizing and implementing a GIS  Helps in determining which kinds of data are needed for a project  Geographic and attribute data work together to provide a complete picture of an object  Both are necessary for comprehensive GIS analysis and visualization  Understanding the distinction and relationship between spatial and attribute data is fundamental to effectively using and implementing GIS for various applications and analyses.  In the context of information technology, both types of data are typically stored in computer files. Mohamed Shawky REN R 201 – Fall Term 2024 6 Week 2 Introduction to Geomatic Techniques in Natural Resource Management  Two predominant strategies to represent locations and extents in digital format: Vector: Points, Lines, and Polygons; approximate the shapes of their real-world counterparts. Raster: Digital image. Vector Data Structure Geometry Description Characteristics Examples Type Zero-dimensional Tree locations Point A single location Defined by x,y coordinates Building centroids No length or area Cities on a small-scale map One-dimensional Line -Roads Has length Linear features Rivers (Polyline) No area Contour lines Connected points Two-dimensional Land parcels Has area and perimeter Polygon Enclosed areas Lakes Closed shape Administrative boundaries A series of connected lines Vector Data Structure A shapefile in GIS is a simple format for storing the geometric location and attribute information of geographic features. It is an Esri vector data storage format that contains one feature class, Mohamed Shawky REN R 201 – Fall Term 2024 7 Week 2 Introduction to Geomatic Techniques in Natural Resource Management representing geographic features as points, lines, or polygons (areas). Itconsists of multiple related files, each serving a specific purpose. ESRI Shapefile Format:.shp: The main file that stores the feature geometry..shx: The index file that stores the index of the feature geometry..dbf: The dBASE table that stores the attribute information of features..prj: The file that stores the coordinate system information. Esri Shapefile Format Extension Name Purpose Simple Explanation Example Stores Contains the actual stores the city.shp ShapeFile feature shapes (points, lines, or boundaries as polygons geometry polygons) Helps quickly find the Acts like a table of Shape Indexes the shape for a specific.shx contents for quick Index File geometry point without searching feature lookup through all shapes For cities: Name, Stores Like a spreadsheet with Attribute Population, Area, etc..dbf feature information about each Table (e.g., “Edmonton, attributes shape population, area) Defines Specifies how the map Ensures vector data Projection.prj coordinate should be positioned on appears in the correct File system Earth location on a world map Mohamed Shawky REN R 201 – Fall Term 2024 8 Week 2 Introduction to Geomatic Techniques in Natural Resource Management The attribute table for a shapefile is stored in the dBASE file component. It contains tabular data associated with each feature in the shapefile. Each row represents a feature, corresponding to a geometry in the.shp file. Columns contain attributes (properties) of the features. It can store various data types including text, numbers, and dates. Random example of an attribute table. Sample Pb Cd Hg As Soil Lat. Long. LandUse ID ppm ppm ppm ppm Texture S001 41.87 -87.62 35.2 0.8 0.15 6.3 Sandy Loam Urban Park S002 41.87 -87.62 42.1 1.2 0.22 7.8 Clay Loam Industrial Area S003 41.87 -87.63 28.7 0.6 0.18 5.5 Silt Loam Residential S004 41.87 -87.63 39.5 1.0 0.20 6.9 Loamy Sand Agricultural Raster Data Structure  Raster/Grid: represents geospatial data as a matrix of cells (pixels).  Image: a digital or photographic representation of geographic areas, often in raster format. Aerial Photograph: captured from the air and used for detailed geographic analysis. Grid is defined by:  Extent  Number of rows and columns  Cell size  (X,Y) coordinates  NoData value Mohamed Shawky REN R 201 – Fall Term 2024 9 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Raster Metadata: lists sensor and product information,  product level, imagery acquisition date, resolution, processing history, and sun and sensor elevation. Raster image Mohamed Shawky REN R 201 – Fall Term 2024 10 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Examples of Raster Data Used in GIS: Era of Big Geospatial Data Resolution Sensor Satellite Spatial Temporal Spectral Radiometric Optical Landsat 8 15m (panchromatic), 30m 16 days 11 bands (visible, 12-bit (multispectral), 100m NIR, SWIR, (thermal) thermal) Landsat 9 15m (panchromatic), 30m 16 days 11 bands (visible, 14-bit (multispectral), 100m NIR, SWIR, (thermal) thermal) ASTER 15m (VNIR), 30m (SWIR), 16 days 14 bands (VNIR, 8-bit 90m (TIR) SWIR, TIR) SPOT 6,7 1.5m (panchromatic), 6m Daily 4 bands (visible, 8-bit (multispectral) NIR, SWIR) MODIS 250m, 500m, 1000m 1-2 days 36 bands (visible 12-bit to thermal infrared) Sentinel-2 10m, 20m, 60m 5 days 13 bands (visible, 12-bit (with 2 NIR, SWIR) satellites) Microwave Sentinel-1A 5m (IW mode), 20m (EW 6-12 days C-band SAR 8-bit mode) Mohamed Shawky REN R 201 – Fall Term 2024 11 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Modelling the world with GIS  Five components of GIS work together to enable spatial environment modeling.  A model is an abstraction or simplification of reality, essential for understanding and communicating complex systems.  Models, by nature, simplify reality by focusing on key elements and interactions within a system.  A critical quality of models is their ability to be reproduced, allowing for validation and verification of results.  Scenario-based and spatial optimization models allow users to analyze and visualize complex geographic data, helping in decision-making processes.  Some models are based on universal principles, making them applicable across different contexts and even planetary systems.  Models are crucial for comprehending and explaining how intricate systems function.  Conceptual models are like simplified pictures or diagrams that help us understand complicated things in nature. Imagine you're trying to explain to a child how rain works. You wouldn't start with complex physics equations? Instead, you might draw a simple picture showing:  The sun heating up water in the ocean.  Water turning into vapor and rising into the sky.  Clouds forming from this vapor.  Rain falling from the clouds back to the earth.  Examples like the hydrologic cycle demonstrate how conceptual models can represent complex natural processes.  Model optimization is the process of adjusting a model's parameters or structure to achieve the best possible performance or results for a given task or objective. Mohamed Shawky REN R 201 – Fall Term 2024 12 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Data Types in GIS A phenomenon in GIS refers to any observable fact, situation, or entity in the world. In the context of GIS, phenomena are broadly categorized into two types: discrete and continuous. This categorization is crucial for determining how these phenomena are represented, analyzed, and visualized in GIS. When choosing between discrete and continuous representations, consider the nature of the phenomenon and the analysis requirements. The classification affects how the phenomena are represented and analyzed in GIS. Different data models may be required for different types of phenomena. Some phenomena can be represented as both discrete objects and continuous fields, depending on the scale and purpose of the study. Spatial Data describes "Where," while Non-Spatial Data covers "What" and "When." Attributes in GIS answer What, When, or Where questions about phenomena. Both spatial and non-spatial data can be qualitative or quantitative. Qualitative and quantitative data are measured on different scales. Attribute Tables in GIS: Are typically considered non-spatial data. They contain information about spatial features. Are usually organized in a tabular format. Each row (record) corresponds to a specific feature. Each column represents a different attribute or characteristic. It can store various data types including text, numbers, and dates. Mohamed Shawky REN R 201 – Fall Term 2024 13 Week 2 Introduction to Geomatic Techniques in Natural Resource Management While the attribute table itself is non-spatial, it's linked to spatial data. This link is through a unique identifier that connects each record to a specific geographic feature. Attributes can be qualitative (e.g., city names) or quantitative (e.g., population numbers). They are stored in the dBASE file. Main Data Types in GIS 1) Quantitative Data (numbers and measurements): Numerical data that can be measured, counted, or calculated. It represents the actual quantity of land surface characteristics in each pixel or feature. 2) Qualitative Data (categories and descriptions): Categorical or descriptive data that represents the qualities of a phenomenon without giving numeric information. It is often textual or coded and describes attributes like types, categories, or classifications. Mohamed Shawky REN R 201 – Fall Term 2024 14 Week 2 Introduction to Geomatic Techniques in Natural Resource Management "Summary of data types in GIS" by June Skeeter, licensed under CC BY-SA 4.0 Mohamed Shawky REN R 201 – Fall Term 2024 15 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Quantitative Data Types Aspect Continuous Data Discrete Data Definition Can take any value within a range Can only take specific, distinct values Nature Infinitely divisible (between any two Occurs in distinct, separate units values, there are always more possible values) Countability Cannot be counted, only measured Can be counted Boundaries No clear boundaries between values Clear boundaries between values Data Typically vector (points, lines, Typically raster (continuous grid of Representation polygons) cells) Measurement Exact coordinates and boundaries Often interpolated values across cells Spatial Variation Properties constant within each Properties can vary continuously object/feature across cells Ratio Scale Has a true zero point Has a true zero point Interval Scale No true zero point No true zero point Continuous Continuous Ratio Discrete Ratio Discrete Interval Interval (1) Tree height (m) (1) Temperature (1) Number of trees (1) Tree size classes (1-5). (2) Trunk diameter (°C). Species count. (2) Forest fire danger rating (cm). (2) pH of forest (2) Number of (1-5). (3) Leaf area index. soil. offspring (3) Difference in fire danger (4) Stream flow rate (3) Species Predation events. ratings. (m³/s). diversity indices. (4) Average habitat quality (5) Population density Habitat quality score. (individuals/km²). scores. Mohamed Shawky REN R 201 – Fall Term 2024 16 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Qualitative Data Types Aspect Nominal Scale Ordinal Scale Definition Categories without ranking or Categories with ranking or directionality. direction. (1) No inherent order. (1) Has a meaningful order. Characteristics (2) Categories are just different. (2) Intervals may not be equal. (1) Flood risk zones (low, medium, high). (1) Land use categories (residential, commercial, industrial). (2) Vegetation density (sparse, moderate, Examples dense). (2) Soil types (clay, silt, sand). (3) Place names. (3) Road classifications (local, collector, arterial, highway). Categorizing features without Representing ordered categories or GIS Applications implying hierarchy. levels of intensity. Binary data: a type of qualitative or categorical data.  A type of qualitative data because it categorizes observations into two distinct groups.  With only two possible values, binary data is the simplest form of categorical data.  It falls under nominal data, as the categories (often represented as 0 and 1) are mutually exclusive and have no inherent order.  In statistics, binary data is sometimes called dichotomous data or quantal data.  While binary data uses numbers (0 and 1), these numbers are used as categorical labels rather than for numerical calculations.  Examples: Common binary categories include yes/no, true/false, and presence/absence. Mohamed Shawky REN R 201 – Fall Term 2024 17 Week 2 Introduction to Geomatic Techniques in Natural Resource Management  Binary models used in habitat suitability modeling as either suitable (1) or unsuitable (0) for a species. Note: Binary data is fundamentally qualitative, but it can be treated statistically as numeric for analysis purposes. Although binary data is qualitative, representing it as 0 and 1 allows for numeric analysis without changing its fundamental nature. Coding binary data as 0 and 1 simplifies statistical computations and model fitting in various analyses. While treating binary data as numeric can be useful, it's essential to remember its categorical origin to avoid misinterpretation. Mohamed Shawky REN R 201 – Fall Term 2024 18 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Different Data Types in the context of Different GIS Operations Continuous Discrete Operations Binary Nominal Ordinal (Interval/Ratio) (Interval/Ratio) The values can be counted Yes Yes Yes Yes Yes The values have 'order' Yes Yes Yes Can quantify the difference Yes Yes between values Has a true zero No (Interval), Yes No (Interval), (Ratio) Yes (Ratio) Can perform spatial analysis Yes Yes Yes Yes Yes Simple Key dis nc ons:  Binary is limited to two op ons.  Nominal categories have no inherent order.  Ordinal categories have a meaningful order.  Con nuous can have any value, including frac ons.  Discrete is limited to whole numbers or countable units. Mohamed Shawky REN R 201 – Fall Term 2024 19 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Some Mathematical and statistical operations for different data types in GIS Con nuous Discrete Opera on Binary Nominal Ordinal (Interval/Ra o) (Interval/Ra o) Addi on No No No Yes Yes Subtrac on No No No Yes Yes Mul plica on No No No Yes (Ra o only) Yes (Ra o only) Division No No No Yes (Ra o only) Yes (Ra o only) Mean No No No Yes Yes Median No No Yes Yes Yes Mode Yes Yes Yes Yes Yes Reclassifica on Yes Yes Yes Yes Yes Map Algebra (Local Opera ons) Limited Limited Limited Yes Yes Mohamed Shawky REN R 201 – Fall Term 2024 20 Week 2 Introduction to Geomatic Techniques in Natural Resource Management How do binary, nominal, ordinal, interval, and ratio data types differ in their applications? Binary Data:  Used for variables with only two possible states (e.g. yes/no, true/false).  Applications:  Representing disturbance events (e.g., fire occurrence: yes/no).  Classifying land cover as forest or non-forest. Nominal Data:  Used for categorizing data into mutually exclusive groups without order.  Applications:  Categorizing forest types (e.g., deciduous, coniferous, mixed).  Classifying soil types in forest ecosystems.  Identifying tree species in forest inventories.  Categorizing land use/land cover types. Ordinal Data:  Used for ordered categories without fixed intervals between them.  Applications:  Ranking habitat quality (e.g., poor, moderate, good, excellent).  Classifying forest successional stages.  Categorizing forest fire intensity levels.  Ranking conservation priority areas. Interval Data:  Used for ordered data with equal intervals between values, but no true zero point  Applications: Mohamed Shawky REN R 201 – Fall Term 2024 21 Week 2 Introduction to Geomatic Techniques in Natural Resource Management  Temperature (Celsius/Fahrenheit).  Assessing pH levels in soil or water bodies in ecosystems.  Using elevation data in terrain analysis for forest management.  Applying vegetation indices (e.g., NDVI) derived from remote sensing. Ratio Data:  Used for ordered data with equal intervals and a true zero point.  Applications:  Temperature (Kelvin).  Measuring tree height, diameter, or volume in forest inventories.  Quantifying biomass or carbon stocks in forests.  Calculating species abundance or density in biodiversity studies.  Measuring distances in spatial analyses of ecosystems. Key differences in applications:  Binary and nominal data are used for categorization without order.  Ordinal data introduces order but lacks precise measurement.  Interval data allows for precise measurement and most statistical analyses.  Ratio data enables most mathematical operations and comparisons. As you move from binary to ratio data, the level of measurement precision increases, allowing for more sophisticated statistical analyses and interpretations. The choice of data type depends on the nature of the variable being measured and the intended analysis. Mohamed Shawky REN R 201 – Fall Term 2024 22 Week 2 Introduction to Geomatic Techniques in Natural Resource Management Note: The Kelvin scale is described as an "absolute" temperature scale, directly related to the average kinetic energy of particles, which aligns with the properties of a ratio scale. In contrast, Celsius and Fahrenheit are interval scales because they have arbitrary zero points that do not represent the absence of temperature. References Geomatics for Environmental Management: An Open Textbook for Students and Practitioners (opengeomatics.ca). https://www.opengeomatics.ca/index.html Introduction – Introduction to Geomatics (usask.ca), https://openpress.usask.ca/introgeomatics/front-matter/introduction/ Essentials of Geographic Information Systems - Table of Contents (saylordotorg.github.io). https://saylordotorg.github.io/text_essentials-of-geographic-information-systems/index.html Gomarasca, M.A. Basics of geomatics. Appl Geomat 2, 137–146 (2010). https://doi.org/10.1007/s12518-010-0029-6. Acker, J. G., & Leptoukh, G. (2007). Online Analysis Enhances Use of NASA Earth Science Data. Eos, Transactions American Geophysical Union, 88(2), 14-17. https://doi.org/10.1029/2007EO020003 Beaudoing, H., & Rodell, M. (2020). GLDAS Noah Land Surface Model L4 monthly 0.25 x 0.25 degree V2.1. Goddard Earth Sciences Data and Information Services Center (GES DISC). Retrieved August 12, 2024, from https://doi.org/10.5067/SXAVCZFAQLNO Rodell, M., Houser, P. R., Jambor, U., Gottschalck, J., Mitchell, K., Meng, C., Arsenault, K., Cosgrove, B., Radakovich, J., Bosilovich, M., Entin, J. K., Walker, J. P., Lohmann, D., & Toll, D. (2004). The Global Land Data Assimilation System. Bulletin of the American Meteorological Society, 85(3), 381-394. https://doi.org/10.1175/BAMS-85-3-381 Mohamed Shawky REN R 201 – Fall Term 2024 23 Week 3 Introduction to Geomatic Techniques in Natural Resource Management Datum, Coordinate System, Projection Note: Additional reading is required for this topic. Concept Definition Purpose Relationship Coordinate A framework for Provides a way to Forms the basis for both System defining locations using uniquely identify geographic and projected numbers positions coordinate systems Datum Defines the origin and A model of the Earth's Provides a reference orientation of a shape and size surface for mapping coordinate system Geographic Uses latitude and Based on a specific Coordinate Represents locations on longitude on a datum; no projection System the Earth's surface spheroid involved Projection Mathematical Converts geographic transformation of the Allows representation of coordinates to planar Earth's surface onto a the Earth on a flat map coordinates flat plane Projected Combines a geographic Coordinate Uses linear units on a Represents locations on a coordinate system, System flat surface flat map datum, and a specific projection Relationship between datums, coordinate systems, and projections Key points about their relationship:  A coordinate system is always based on a specific datum.  A projection requires both a coordinate system and its underlying datum to transform 3D locations to 2D. Mohamed Shawky REN R 201 – Fall Term 2024 1 Week 3 Introduction to Geomatic Techniques in Natural Resource Management  The choice of datum affects the accuracy of the coordinate system, which in turn impacts the projection.  Different projections can be applied to the same coordinate system and datum combination. Datums A datum is a standard reference point, set of points, or surface from which survey measurements are based  It provides a frame of reference for measuring locations on the Earth's surface.  Datums are crucial for any technology or technique based on spatial location, including geodesy, navigation, surveying, GIS, remote sensing, and cartography. There are three main types of datums:  Horizontal Datums:  Used to measure horizontal positions across the Earth's surface in latitude and longitude.  Define the origin and orientation of latitude and longitude lines.  Examples: NAD83, WGS84.  Vertical Datums:  Used to measure elevations and water depths.  Provide a reference surface for measuring heights, usually based on mean sea level.  Example: NAVD88 (North American Vertical Datum of 1988).  Three-Dimensional Datums:  Modern datums, especially those used with GPS.  These are truly three-dimensional, providing latitude, longitude, and height information in a unified form.  Enable the expression of both horizontal and vertical position components in a unified form. Mohamed Shawky REN R 201 – Fall Term 2024 2 Week 3 Introduction to Geomatic Techniques in Natural Resource Management  Also known as geometric datums. Standard Datum Specification  Includes Earth's shape model (ellipsoid or geoid), origin tied to a known location, and control points for measuring coordinates.  A datum in GIS is a reference system used to precisely measure and represent locations on Earth. It provides a frame of reference for defining coordinate systems and map projections. Geocentric vs. Local Datums  Geocentric Datums:  Use the Earth's center of mass as the origin.  Designed for global use.  Example: WGS84 (World Geodetic System 1984).  Local Datums:  Align their spheroid to closely fit the Earth's surface in a particular area.  Designed for use in specific regions.  Examples: NAD27 (North American Datum 1927), ED50 (European Datum 1950). Importance in GIS  Different datums can result in significantly different coordinate values for the same location.  Using consistent datums is critical for accurate overlay and analysis of spatial data  Datum transformations are often necessary when working with data from different sources or regions.  Understanding datums is essential for GIS professionals to ensure accurate representation, measurement, and analysis of spatial data across different coordinate systems and regions. Mohamed Shawky REN R 201 – Fall Term 2024 3 Week 3 Introduction to Geomatic Techniques in Natural Resource Management Coordinate System A coordinate system is a standardized method for identifying the location of a point on the earth's surface or in space using numbers or coordinates. It provides a framework to define, represent, and measure the spatial location of features. Types of Coordinate Systems: 2D Coordinate Systems: a) Cartesian Coordinate System (2D):  Uses two perpendicular axes (X and Y).  Points are represented as ordered pairs (x, y).  Imagine a flat grid with horizontal (X) and vertical (Y) lines. b) Polar Coordinate System:  Uses distance from origin (r) and angle from a reference direction (θ).  Points are represented as (r, θ).  Imagine a circle with radius lines and concentric circles. 3D Coordinate Systems: a) Cartesian Coordinate System (3D):  Uses three perpendicular axes (X, Y, and Z).  Points are represented as ordered triples (x, y, z).  Imagine a cube with three perpendicular edges meeting at a corner. b) Cylindrical Coordinate System:  Uses distance from Z-axis (r), angle in XY-plane (θ), and height (z).  Points are represented as (r, θ, z).  Imagine a cylinder with radius lines, circular levels, and a vertical axis. c) Spherical Coordinate System: Mohamed Shawky REN R 201 – Fall Term 2024 4 Week 3 Introduction to Geomatic Techniques in Natural Resource Management  Uses distance from origin (r), angle from Z-axis (θ), and angle in XY-plane (φ)  Points are represented as (r, θ, φ)  Imagine a sphere with latitude-like and longitude-like lines In GIS and mapping, two main types of coordinate systems are used:  Geographic Coordinate System (GCS):  Uses latitude and longitude on a spheroid.  Based on a three-dimensional ellipsoidal surface.  Example: WGS84.  Projected Coordinate System (PCS):  Uses linear units (e.g., meters, feet) on a flat surface.  Derived from a GCS using map projections.  Example: UTM (Universal Transverse Mercator). Each type of coordinate system has its advantages and is used for different purposes in various fields such as mathematics, physics, engineering, and geospatial sciences. Mohamed Shawky REN R 201 – Fall Term 2024 5 Week 3 Introduction to Geomatic Techniques in Natural Resource Management Projection Projection Concept:  Imagine placing a light source inside the Earth.  The light casts shadows of the globe's features onto a surrounding surface.  Consider the surface is a piece of paper wrapped around the globe.  Trace the shadows onto the paper.  Flatten out the piece of paper.  The result is map projection. Projection Concept (Microsoft Designer) Objectives:  This method illustrates how 3D globe features are transferred to a 2D map surface.  It also demonstrates why all map projections involve some level of distortion. Mohamed Shawky REN R 201 – Fall Term 2024 6 Week 3 Introduction to Geomatic Techniques in Natural Resource Management Results:  Areas where the paper touches the globe are called points or lines of tangency.  Point of tangency: Where the projection surface touches the globe at a single point.  Line of tangency: Where the projection surface touches the globe along a line.  These areas of contact are exactly replicated on the map with no distortion.  Areas close to the points or lines of tangency are most accurate.  Locations farther from these points or lines experience greater distortion. Practical implications:  Cartographers choose projections with points or lines of tangency that minimize distortion in the areas of interest for their maps.  Variations:  Some projections use secant surfaces that intersect the globe rather than just touching it, which can distribute distortion differently.  Understanding points and lines of tangency is crucial for selecting appropriate map projections and interpreting the accuracy of different areas on a map. Key Concept:  No perfect projection exists; all involve some form of distortion. Mohamed Shawky REN R 201 – Fall Term 2024 7 Week 3 Introduction to Geomatic Techniques in Natural Resource Management Comparison between tangent and secant projections: Type Tangent Projection Secant Projection Touches the globe along a single line Intersects the globe along two lines Example: Standard Mercator Example: Transverse Mercator Cylindrical Distortion increases away from the line of Distortion is minimized between the two tangency lines of intersection Touches the globe along a single parallel Intersects the globe along two parallels of of latitude latitude Example: Lambert Conformal Conic (with Conic Example: Albers Equal-Area Conic one standard parallel) Distortion increases away from the Distortion is minimized between the two standard parallel standard parallels Touches the globe at a single point Intersects the globe along a circular area Example: Gnomonic projection Example: Stereographic projection Planar Distortion increases radially from the Distortion is minimized within the circle of point of tangency intersection Mohamed Shawky REN R 201 – Fall Term 2024 8 Week 3 Introduction to Geomatic Techniques in Natural Resource Management Comparison between tangent and secant projections. https://en.m.wikipedia.org/wiki/File:Comparison_of_cartography_surface_development.svg. Latitude (φ) Tangent Projections:  The developed surface (plane, cone, or cylinder) touches the globe at a single point or line.  Scale is true (1.0 or unity) at the point or line of tangency.  Scale compression occurs as you move away from the point or line of tangency towards the center of the map. Mohamed Shawky REN R 201 – Fall Term 2024 9 Week 3 Introduction to Geomatic Techniques in Natural Resource Management  Scale expansion occurs as you move away from the point or line of tangency towards the edges of the map. Secant Projections:  The developed surface intersects the globe along two lines (for conic and cylindrical) or a circle (for planar).  Scale is true (1.0 or unity) along these lines or circle of intersection.  Scale compression occurs between the lines of intersection. Scale expansion occurs outside the lines of intersection. Scale compression and expansion:  Refer to how distances on a map are distorted compared to the actual distances on the Earth's surface.  Compression: Distances on the map are shorter than in reality.  Expansion: Distances on the map are longer than in reality. Scale Factor:  In both types of projections, the scale factor indicates how much expansion or compression is occurring at any given point on the map. A scale factor less than 1.0 indicates compression. A scale factor greater than 1.0 indicates expansion.  Tangent projections have one line of true scale with compression on one side and expansion on the other, while secant projections have two lines of true scale with Mohamed Shawky REN R 201 – Fall Term 2024 10 Week 3 Introduction to Geomatic Techniques in Natural Resource Management compression between them and expansion beyond them. This characteristic of secant projections allows for more balanced distortion across larger areas. Tangent Projection Secant Projection Contact with Globe Touches at a single point or line Intersects at two lines or a circle Lines of True Scale One Two Scale Factor at 1.0 (true scale) 1.0 (true scale) Contact Scale Near Contact < 1.0 (compression) > 1.0 (expansion) Scale Away from < 1.0 (compression) between lines > 1.0 (expansion) Contact > 1.0 (expansion) beyond lines Increases uniformly away from Distortion Pattern More evenly distributed contact Area of Acceptable Smaller Larger Distortion - Simple conceptually - Better for larger areas Remarks - Good for small areas near - More complex mathematically contact - Often preferred for regional mapping Tangent vs secant projections. Mohamed Shawky REN R 201 – Fall Term 2024 11 Week 3 Introduction to Geomatic Techniques in Natural Resource Management NAD 1983 10TM AEP Forest is a projected coordinate system used primarily in Alberta, Canada for forestry and resource management purposes. This coordinate system is commonly used in various Alberta government mapping projects and forestry management applications. It provides accurate representation of forest areas and resources, facilitating better management and decision-making processes in the forestry sector. Characteristics  EPSG Code: 3400 (also known as ESRI:102184) EPSG stands for European Petroleum Survey Group. It is a standardized system for identifying and defining coordinate reference systems and related geospatial parameters, widely used in the GIS and mapping community.  Geographic Coordinate System: NAD83 (North American Datum 1983).  Projection: Transverse Mercator.  Area of Use: Canada – Alberta.  Specific Projection Parameters Configuration: This configuration allows for accurate mapping and analysis of forest resources across Alberta while maintaining positive coordinate values and minimizing distortion. I. Central Meridian: -115 degrees  This is the longitude line at the center of the projection on Alberta.  It runs down the middle of the map, and the map is typically symmetrical on either side of it.  The -115° longitude was chosen as it passes through Alberta. Mohamed Shawky REN R 201 – Fall Term 2024 12 Week 3 Introduction to Geomatic Techniques in Natural Resource Management II. Latitude of Origin: 0 degrees  This defines the starting point for the y-coordinates (northings).  Setting it to 0° means the equator is used as the origin for y-coordinates.  False northing of 0 mean y-coordinates directly represent distance from the equator in meters. III. Scale Factor: 0.9992  This is a multiplier applied to reduce distortion in the projection. IV. False Easting: 500,000 meters  This is a value added to all x-coordinates (eastings) in the projection.  It's used to ensure all x-coordinates are positive, eliminating negative numbers. V. False Northing: 0 meters  This is a value added to all y-coordinates (northings).  In this case, it's set to 0, meaning no offset is applied to the y-coordinates. Note:  NAD 1983 10TM AEP Forest is a projected coordinate system. However, every projected coordinate system is based on an underlying geographic coordinate system. In this case, this projected system is based on the geographic coordinate system NAD83.  NAD 1983 10TM AEP Forest can be converted to other coordinate systems using ArcGIS Pro 3.x. For example, it can be transformed to WGS84 (EPSG:4326) for use in global mapping applications or GPS devices. Mohamed Shawky REN R 201 – Fall Term 2024 13 Week 3 Introduction to Geomatic Techniques in Natural Resource Management Relationship between Projected and Geographic Coordinate Systems:  Geographic Coordinate System (GCS): NAD83 is the underlying geographic coordinate system. It defines the shape of the Earth and the reference frame for measuring locations on the Earth's surface using latitude and longitude.  Projected Coordinate System (PCS): NAD 1983 10TM AEP Forest is the projected coordinate system that transforms the curved surface of the Earth (as defined by NAD83) onto a flat plane.  Projection: The Transverse Mercator projection is used to convert the geographic coordinates (latitude and longitude) into planar coordinates (easting and northing). Why Both Are Mentioned:  When defining a projected coordinate system, it's essential to specify:  The underlying geographic coordinate system (in this case, NAD83)  The projection method (Transverse Mercator)  The specific parameters of the projection (central meridian, scale factor, false easting, etc.)  This complete definition allows for accurate transformation between geographic and projected coordinates and ensures that the projected coordinates correctly represent locations on the Earth's surface. Mohamed Shawky REN R 201 – Fall Term 2024 14 Week 3 Introduction to Geomatic Techniques in Natural Resource Management References Geomatics for Environmental Management: An Open Textbook for Students and Practitioners (opengeomatics.ca). https://www.opengeomatics.ca/index.html Introduction – Introduction to Geomatics (usask.ca), https://openpress.usask.ca/introgeomatics/front-matter/introduction/ Essentials of Geographic Information Systems - Table of Contents (saylordotorg.github.io). https://saylordotorg.github.io/text_essentials-of-geographic-information-systems/index.html Gomarasca, M.A. Basics of geomatics. Appl Geomat 2, 137–146 (2010). https://doi.org/10.1007/s12518-010-0029-6. Acker, J. G., & Leptoukh, G. (2007). Online Analysis Enhances Use of NASA Earth Science Data. Eos, Transactions American Geophysical Union, 88(2), 14-17. https://doi.org/10.1029/2007EO020003 Beaudoing, H., & Rodell, M. (2020). GLDAS Noah Land Surface Model L4 monthly 0.25 x 0.25 degree V2.1. Goddard Earth Sciences Data and Information Services Center (GES DISC). Retrieved August 12, 2024, from https://doi.org/10.5067/SXAVCZFAQLNO Rodell, M., Houser, P. R., Jambor, U., Gottschalck, J., Mitchell, K., Meng, C., Arsenault, K., Cosgrove, B., Radakovich, J., Bosilovich, M., Entin, J. K., Walker, J. P., Lohmann, D., & Toll, D. (2004). The Global Land Data Assimilation System. Bulletin of the American Meteorological Society, 85(3), 381-394. https://doi.org/10.1175/BAMS-85-3-381 Mohamed Shawky REN R 201 – Fall Term 2024 15 Week 4 Introduction to Geomatic Techniques in Natural Resource Management Map Projections Aspects of map projections, including the projection type:  The aspect of a projection refers to the orientation of the projection surface (cylinder, cone, or plane) relative to the Earth's axis.  Projection surface: This is the geometric shape (plane, cylinder, or cone) onto which the Earth's surface is projected to create a flat map.  Earth's axis: This is the imaginary line that runs through the Earth's center from the North Pole to the South Pole, around which the Earth rotates.  Alignment: When the projection surface's axis aligns with Earth's axis, it means:  For cylindrical projections: The cylinder wraps around the Earth with its axis coinciding with Earth's rotational axis.  For conic projections: The cone's axis is the same as Earth's rotational axis.  For planar projections: The plane is perpendicular to Earth's axis, typically touching at a pole. Planar (Azimuthal) Aspect Description Cylindrical Conic “Special Description” Projection Cone touches or Cylinder touches or Polar (Normal): surface's axis intersects Earth Normal intersects Earth Plane tangent to a aligns with Earth's along one or along equator pole axis two parallels Projection Cylinder touches or Cone's axis lies Equatorial: Plane surface's axis is Transverse intersects Earth in equatorial tangent to a point perpendicular to along a meridian plane on equator Earth's axis Cylinder touches or Cone's axis Projection Oblique: Plane intersects Earth passes through surface's axis is tangent to any Oblique along a great circle center of Earth tilted relative to point between other than equator but not through Earth's axis pole and equator or meridian poles  The quality of a projection is best where the projection surface touches or intersects the Earth's surface. Mohamed Shawky REN R 201 – Fall Term 2024 1 Week 4 Introduction to Geomatic Techniques in Natural Resource Management  Changing the aspect allows for better representation of specific regions. For ex., a transverse cylindrical projection can provide accurate representation of areas far from the equator.  The distortion properties of a given projection surface remain unchanged when the aspect is changed, but the distribution of distortions across the map does change. Aspects of Map Projection. Credit Dr. Rick Pelletier REN R 201 Lecture Notes 2023 Distortion: All projections result in some distortion of the relationships between features on the sphere when they are projected onto a flat surface.  The direction between a feature and surrounding features.  The distance between a feature and surrounding features.  The shape of any feature.  The size of any feature.  Basic Projection Techniques: describes how a map shows positional relationship between two features, and their size and shape. Depending on their intended use, projections are chosen to preserve a particular relationship or characteristics. Mohamed Shawky REN R 201 – Fall Term 2024 2 Week 4 Introduction to Geomatic Techniques in Natural Resource Management 1. Equal-Area Projections:  Preserve the relative sizes of areas on the Earth's surface.  Can compare sizes of countries, continents, or other geographic features.  Distort shapes, especially towards the edges of the map  You can identify most equal area map projections by noting that the meridians and parallels are not at right angles to each other. Additionally, distance distortion is often present on equal area map projections, and the shape is often skewed.  Examples: Albers Equal Area, Lambert Azimuthal Equal Area, Mollweide. Lambert cylindrical equal-area projection. Credit: Image from Map Projection Explorer, NASA, public domain. 2. Conformal Projections:  Preserve local shapes and angles.  Useful for navigation and meteorology  Cannot simultaneously be equal-area.  Can usually be identified by the fact that meridians intersect parallels at right angles and areas are distorted significantly.  Should be used if the main purpose of the map involves measuring angles or representing the shapes of features.  Examples: Mercator, Lambert Conformal Conic, Stereographic 3. Equidistant Projections:  Preserve distances from one or two points to all other points on the map.  Useful for measuring distances from a central point. Mohamed Shawky REN R 201 – Fall Term 2024 3 Week 4 Introduction to Geomatic Techniques in Natural Resource Management  They are neither conformal nor equal area and tend to look less distorted.  Examples: Azimuthal Equidistant, Equirectangular. Mercator Map Projection. Credit: Image from Map Projection Explorer, NASA, public domain. Equidistant Conic Projection. Credit: Image from Map Projection Explorer, NASA, public domain. 4. True Direction (Azimuthal) Projections:  Preserve directions from a central point.  Useful for navigation and showing great circle routes.  True direction from the center: In azimuthal projections, directions (azimuths) are preserved accurately from the center point of the map to all other points on the map. Mohamed Shawky REN R 201 – Fall Term 2024 4 Week 4 Introduction to Geomatic Techniques in Natural Resource Management This means that if you draw a straight line from the center to any other point, it will represent the true direction you would need to travel on the Earth's surface.  Examples: Gnomonic, Azimuthal Equidistant. Azimuthal Equidistant Map Projection. Credit: Image from Map Projection Explorer, NASA, public domain. Key Points:  No projection can preserve all properties simultaneously.  The choice of projection depends on the specific purpose of the map  Some projections attempt to balance multiple properties (e.g., Robinson projection). Comparison between different map projection types based on associated distortion characteristics. Property Preserved Equal-Area Conformal Equidistant True Direction (Azimuthal) Shape Distorted Preserved Distorted Preserved near center Angles Distorted Preserved Distorted Preserved near center Area Preserved Distorted Distorted Distorted Distance Distorted Distorted Preserved* Preserved from center Direction Distorted Distorted Distorted Preserved from center Mohamed Shawky REN R 201 – Fall Term 2024 5 Week 4 Introduction to Geomatic Techniques in Natural Resource Management Preserved near center in the context of map projections:  The property (such as shape, angles, or direction) is accurately represented at the center point of the projection.  As you move away from the center point, the accuracy of that property gradually decreases (gradual distortion).  Directions and distances are most accurate near the center and become less accurate as you move towards the edges of the map. Projection Parameters:  Used to customize projections for specific areas of interest.  Define how the projection relates to the Earth.  Include angular and linear parameters. Purpose of Parameters:  Minimize distortions in the area of interest.  Adapt projections to specific mapping needs.  Ensure accurate representation of Earth's surface on a flat map.  Allow for the creation of custom projections tailored to specific geographic regions or mapping requirements. 1. Angular Parameters: Central Meridian/Longitude of Origin:  Defines the projection's origin. Latitude of Origin:  Defines the origin (starting point) of the y-coordinates (northings) in the projected coordinate system.  The intersection of the Latitude of Origin with the Central Meridian forms the origin point of the projected coordinate system (x, y).  At this latitude, the y-coordinate is typically set to zero, unless a false northing is applied.  It may not always be located at the center of the projection area. Its placement depends on specific projection and the area being mapped.  For global or hemisphere maps, common Latitude of Origin values include 0° (the Equator) or 90° (North or South Pole), depending on projection type. Standard Parallel/Latitude of True Scale: Mohamed Shawky REN R 201 – Fall Term 2024 6 Week 4 Introduction to Geomatic Techniques in Natural Resource Management  Line(s) where the projection surface intersects/touches the globe. Line of no distortion.  A tangent conic or cylindrical projection: 1  Secant conic or cylindrical projection:2 Latitude of Centre/Central Parallel:  Middle latitude of a projection. 2. Linear Parameters: False easting/northing:  Constants added to coordinates to ensure positive values. Scale Factor:  A ratio that compares the actual scale of a map at a specific point or along a specific line to the principal (or stated) scale of the map.  It is known as the 'k-factor' in some contexts.  Actual Scale (also called true scale):  The real, measurable scale at any specific point on a map.  Varies from location to location on the map.  Results from the distortions caused by projecting the Eart