GEG 410: GIS II Lecture 1 Review of Basic GIS - Fall 2024 PDF

GEG 410: GIS II Lecture 1: Review of Basic GIS Fall 2024 Instructor: Dr. Guimin Zhu Email: [email protected] Contents Syllabus Coordinate Systems & Projections Cartography & Choropleth Maps Geocoding Lab 0 – Plot US State Population Densit...

GEG 410: GIS II Lecture 1: Review of Basic GIS Fall 2024 Instructor: Dr. Guimin Zhu Email: [email protected] Contents Syllabus Coordinate Systems & Projections Cartography & Choropleth Maps Geocoding Lab 0 – Plot US State Population Density Grading Lab assignments Item Number Points 1 pre-check + 5 normal labs Lab assignments 6 35% Midterm Midterm exam 1 25% Team project Final team project 1 35% Group of 2-3 people Participation 1 5% Proposal and presentation Total 100% Grad students: extra short paper Course Contents Brief review Spatial pattern Map projections, choropleth maps, Spatial autocorrelation, Geographic selection and join Weighted Regression (GWR) Geodatabases Surface analysis Simple SQL (Structured Query Language) Slope, aspect, flow direction, sink Vector and raster model Spatial interpolation Rasterization and vectorization Kernel Density Estimation (KDE), Inversed Raster analysis Distance Weights (IDW) Reclassification, neighborhood, zonal Network and transportation analysis statistics, map algebra Low-cost path, shortest path, closest Spatial analysis facility Spatial join, overlay, dispersion & distribution patterns Previous Published Papers Contents Syllabus Coordinate Systems & Projections Geographic Coordinate System (GCS) Projected Coordinate System (PCS) Cartography & Choropleth Maps Geocoding Lab 0 – Plot US State Population Density Geographic Coordinate Systems The Earth’s surface is the primary and unique spatial framework for measuring locations The corresponding coordinate system for this framework is called the geographic coordinate system The location (latitude and longitude) are called geographic coordinates Approximation of the Earth The simplest model is a sphere, which is typically used in discussing map projections. But the Earth is not a perfect sphere: the Earth is wider along the equator than between the poles Geodesy: Geoid Geodesy Science of accurately measuring and understanding geometric shape, gravity field, and the orientation in space of the Earth Geoid The hypothetical shape of the earth, coinciding with mean sea level and its imagined extension under land areas Geodesy: Ellipsoid Datum A geodetic datum is a mathematical model of the Earth, which serves as the reference or base for calculating the geographic coordinates in the case of a horizontal datum and for calculating elevations in the case of a vertical datum. A shift of the datum will result in the shift of positions of points. Common Datums: NAD83 and WGS84 NAD83 (North America Datum 1983) is a geocentric datum based on the GRS80 ellipsoid and is currently used by US NGS (National Geodetic Survey) Several realizations (updates) of NAD83 have been made with improved accuracy since the late 1980s WGS84 (World Geodetic System 1984) is used by the U.S. Department of Defense as a global reference system for supporting positioning and navigation WGS84 is the datum for GPS readings Map Projection Map projection is a process that defines how positions on Earth’s curved surface are transformed onto a flat surface Cartesian Coordinate System Plane surface Easy to measure distance and direction Projection examples  Mercator Projection https://www.youtube.com/watch?v=CPQZ7NcQ6YQ Distortion Any projection distorts the Earth in some way Area Shape Distance Some Common Projections UTM: Universal Transverse Mercator Lamber Conformal Conic Best for land masses extending in an east-west orientation at mid-latitudes Web Mercator Auxiliary Sphere Variant of Mercator, widely used in ArcGIS Online base maps and layers Albers Equal Area Conic Best for land masses extending in an east-west orientation at mid-latitudes, e.g., the US Projected Coordinate Systems Unlike geographic coordinate systems that span the entire globe, projected coordinate systems are localized to minimize visual distortion in a particular region Commonly used projected coordinate systems in the US: State Plane UTM Example: State Plane Defined in the US by each state, and each state can have one or more State Plane Coordinate Systems Some states use multiple zones, and each zone uses a different projection Pros: preferred for applications needing very high accuracy, e.g., surveying Cons: it makes regional and national mapping difficult when using maps produced across zones State Plane zones in California Example: UTM UTM: Universal Transverse Mercator The Earth is divided into 60 zones, each zone is 6 degrees in longitude wide from 180 degrees West Zones are split north and south of the Equator Each zone has a unique transverse Mercator projection UTM zones for the lower 48 contiguous states of the US Two map layers are not going to register spatially unless they are based on the same coordinate system. ArcGIS Pro projection on the fly: By default, a map is assigned the coordinate system of the first layer you add to it. Subsequent layers with different coordinate systems are projected to the map’s spatial reference (on the fly) in real time. Contents Syllabus Coordinate Systems & Projections Cartography & Choropleth Maps Reference & thematic maps Choropleth maps Use of colors & classification Geocoding Lab 0 – Plot US State Population Density Basic terminology Cartography The art, science, and technology of making maps Types of maps Reference (general-purpose) maps Emphasize the location of spatial phenomena Prevalent till the mid-18th century Thematic maps Demonstrate particular features or concepts Emphasize the spatial pattern of one or more geographic attributes US topographic map of the Morrison, Colorado area released in 2022 showing standard US Topo layer https://www.usgs.gov/programs/national- geospatial-program/us-topo-maps- america Reference map of Florida https://www.nationsonline.org/onewo rld/map/USA/florida_map.htm Left: reference map of the southern US; right: thematic map of population density Source: Longley et al. Geographic Information Systems and Science, Wiley Types of Thematic Maps Choropleth Proportional symbol Isopleth Dot (density) Choropleth Maps Features are shaded or patterned in proportion to the quantitative value of the features Simple choropleth maps: values are classified into classes Life expectancy in 2014. Source: CNN  Proportional symbol map: sizes in proportion to the magnitude of data occurring at point location Isopleth map: also called contour maps, display lines of equal values Dot density map: a single dot represents one or several occurrences, and dot locations are randomized Map Elements * Usually, you don’t need to include all of them Use of color A color can be described by: Hue (color) Lightness (bright, dark, etc.) Saturation (purity of color) Based on different nature of data, a color ramp can be: Sequential Divergent Qualitative (categories, non-ordered) ColorBrewer https://colorbrewer2.org Use of classification To organize large amounts of information into effective or meaningful categories, bringing relative order and simplicity to complexity Major classification methods: Equal interval Quantile Natural break Standard deviation Bivariate Choropleth Contents Syllabus Coordinate Systems & Projections Cartography & Choropleth Maps Geocoding Lab 0 – Plot US State Population Density Geocoding Also called address geocoding, or address matching Geocoding is the process of assigning a georeferenced location, usually in the form of an address to coordinate values Steps of Geocoding Step 1: prepare data Address event table Address reference theme Address elements Address Reference Theme: Street (Road) Network Data Number 123 Oak St. W, Pittsburgh, PA 15213 From To Street Type Side Parity Street_ID Street name 123 Oak St. W, Pittsburgh, PA 15213 2 98 Oak St R E 5950 Street type 123 Oak St. W, Pittsburgh, PA 15213 1 99 Oak St L O 5950 Direction, suffix 123 Oak St. W, Pittsburgh, PA 15213 100 198 Oak St R E 6011 Direction, prefix 123 W Oak St., Pittsburgh, PA 15213 101 199 Oak St L O 6011 Zone, city 123 Oak St. W, Pittsburgh, PA 15213 Zone, zip code 123 Oak St. W, Pittsburgh, PA 15213  StoreID Address Class Steps of Geocoding 1437 123 Oak St A 1402 333 Pine Ave A 1855 18 Bay Dr B Step 2: Geocoding (Address Matching) Parse and compare an address in an event From To Street Type Side Parity Street_ID table to the addresses of a reference 2 98 Oak St R E 5950 dataset 1 99 Oak St L O 5950 Determine whether an address falls within an address range in the reference dataset 100 198 Oak St R E 6011 (e.g., line) 101 199 Oak St L O 6011 If an address falls with the address range, it’s considered a match and a georeferenced location can be calculated Determining the georeferenced location Possible Problems in Geocoding Variations in street names Fifth Avenue, Fifth Ave., 5th AV Route 1, Dixie Hwy Data entry errors 1300 Campo Sano Ave, Coral Gables, FL 33146 1300 Campo Sano Ave, Coral Gables, FL 33134 Missing street information Place names UM Contents Syllabus Coordinate Systems & Projections Cartography & Choropleth Maps Geocoding Lab 0 – Plot US State Population Density Select a single state: 1. Select by Attribute 2. Data -> Export Features Crop the raster to the state extent: 1. Clip Raster Produce a map layout: 1. Set Symbology 2. Insert -> New Layout 3. Add necessary map elements