Remote Sensing & GIS Fundamentals

• Major Course- MJ 7: Fundamentals of Remote Sensing & GIS
• This course's objective is to explain remote sensing and GIS, familiarize students with satellite remote sensing, data processing, and the uses of GPS and GIS.
• Students will appreciate remote sensing and GIS, map resources, and apply knowledge for sustainable development.

Course Content

• Unit 1 covers the meaning, scope, development, and components of remote sensing, as well as EMR interaction with the atmosphere and Earth's surface.
• Unit 2 involves remote sensing platforms and sensors, satellite imagery interpretation, and visual and digital techniques. It discusses interpretation keys like shape, size, color, tone, and texture, image enhancement, and remote sensing applications.
• Unit 3 defines GIS, its development, elements, and spatial data types, along with raster and vector data structures.
• Unit 4 focuses on coordinate systems, georeferencing, GIS databases, and spatial and non-spatial data.
• Unit 5 covers Digital Elevation Models (DEM), computer-assisted cartography, and GIS integration with remote sensing and GPS.

Coordinate Systems

• A coordinate system assigns coordinates to locations using a set of rules.
• Three-dimensional spatial coordinate systems are utilized to pinpoint data on Earth's surface.
• Coordinates of points on the Earth's surface are required to perform survey operations.
• Coordinates are determined relative to certain coordinate systems.
• A coordinate system needs a clearly defined origin and orientation of coordinate axes (X, Y, Z).
• The Cartesian system is the most frequent in two dimensions.

Brief History

• Euclid (300 BC), the "Father of Geometry," explained theorems in plane geometry and number theory in Alexandria.
• Eratosthenes (276 BC - c. 195 BC) of Cyrene invented a system of longitude and latitude as a librarian, geographer, and astronomer in Alexandria.
• Ptolemy (150 AD) popularized a coordinate system based on latitude and longitude in Alexandria, using degrees, minutes, and seconds.
• René Descartes (1596-1650 AD) conceptualized Cartesian Coordinates, introducing algebra to geometry in 1637.
• The International Meridian Convention in 1884 fixed the prime meridian, choosing the meridian passing through the Royal Observatory in Greenwich, England.
• Satellite Remote Sensing began in 1970.
• GPS opened for public use in 1980, with GIS becoming popular in 1990.

Axioms and Postulates of Euclid

• Sir Thomas Heath's version presents axioms and postulates such as things equal to the same thing are equal to one another.
• If equals are added or subtracted from equals, the wholes or remainders are equal.
• Things that coincide are equal.
• The whole is greater than the part.
• Postulates include drawing a straight line between any two points, producing a finite straight line continuously, describing a circle, and stating that all right angles are equal.
• John Playfair (1748-1819) offered an alternative version of the Fifth Postulate in 1795
• This alternative formulation led to the same geometry as Euclid's.

Geographic Coordinates

• The most widely used Coordinate system have lines of geographic latitude and longitude.
• Lines of equal latitude are called parallels; they create circles on the ellipsoid's surface.
• Lines of equal longitude are meridia and create ellipses on the ellipsoid.
• Parallels and meridians together form the geographic coordinate system.
• The Equator is a line between the northern and southern ends of the axis dividing the sphere into 2 halves.
• Latitude measures the angular distance from equator to north or south.
• Longitude measures the angular distance from equator to east or west, running between north and south.

Meridian/Longitude Origin

• Early country wanted their own 0° meridian passing through their location.
• Increased trade and contacts led to the need to resolve this.
• A meeting in Paris in 1634 suggested using 19° 55'03" of Paris as the prime meridian.
• In 1884, Washington D.C. decided Greenwich meridian would be used.
• Some old maps use prime meridians through Ferro, the Pantheon in Paris, or Madrid.

Geocentric Coordinates (X,Y,Z)

• The system originates at Earth's mass-center.
• The x and y axes are in equator plane.
• The x-axis passes through Greenwich meridian.
• The z-axis aligns with Earth's rotational axis.
• The three axes are orthogonal and form a right-handed system.

Polar Coordinates

• Distance d from origin to point.
• Angle "a" between fixed direction and point direction.
• "a" known as azimuth or bearing.
• Measurement of a bearing is performed clockwise.
• Given in radial distance and direction from a common point.
• Bearings always related to bearing or datum line.

Cartesian Coordinates

• Use plane rectangular coordinates to define a point in a plane.
• Based on intersecting perpendicular lines, X and Y axes.
• Horizontal axis is X (Easting), vertical is Y (Northing).
• The intersection of the X- and Y- axes forms the origin.
• Rectangular coordinates are also known as Cartesian coordinates.
• Named after French philosopher and mathematician René Descartes.
• Is most commonly used coordinate system.
• Applications in photography, computer science, geography.
• Fundamental to vectors and analytic geometry.

Reference Lines

• In principle, can be chosen freely.
• Three directions are widely used: Real North, Net North and Magnetic North.
• Compass bearing is one option that is widely used, however also grid and geodetic.
• Polar coordinates often are often used in land surveying.

Map Grid and Graticule

• The grid has lines of the constant rectangular coordinates.
• The grid is commonly rectangular for medium and large
• Plane coordinates are not utilized in the small scale for million map.
• Scale distortions usually very high in small scale maps.
• The graticule represents projected positions for intervals.
• Shape depends on what scale and way the product is used.

Representation of Earth Points

• Horizontal: Ellipsoid (mathematical) with major axis high, minor axis low, corresponding to latitude and longitude.
• Vertical: Geoid, sphere is same. Datums:
• Datum allows for identifying lat/lon of the earth on a 'round' object.
• WGS 84 is reference plane sphere.

Datum

• Datum allows for identifying lat/lon & height of the earth.
• The basic globe with grid lines is called is mathematical/geometric principle.
• Math: "round" area representing Earth's surface.
• Calculations fit mathematical model to Earth's surface (Equator, North/South Poles, lat/lon).
• Local Ellipsoids include North American, Tokyo, European, Potsdam, and Everest datums.
• There are different ways to fit in mathematical model the Earth's surface .
• Reference point : fixed starting point (e.g. for scale).
• Horizontal datum = ellipsoid.
• Vertical datum = geoid.
• Everest MSL is reference plane spherical shape.
• World Geodetic System created 1984/WGS84.

Geoid

• Geoid: hypothetical solid figure corresponding to estimated sea level and visualized extension.
• Is considered a level location with approzimate mass sea level, indicates Earth's size/shape.
• Mathematical surface is complex to measure accurately.
• Gravity is measured with gravity.
• Geoid: Mass Sea levels are about equal; also can very different over continental areas.
• Variable Gravity occurs depending upon items, geoid/ inconsistent plane.
• Regarded as = to mid sea altitude when looking at the geoid from planet earth.

Types of Coordinate Systems

• Based on earth's characteristics: curvy or euclidean
• Reference for regional (local) system for global system
• Center (e.g. of Earth as a reference point
• Non- geocentric e.g. NAD or Everest)
• World Geodetic System is 1984 worldwide with locations
• Application for satellite like (GPS) system used
• International terrestrial benchmark setup in a frame
• American north datum
• Everest: (1830s, Sir George India's Geo ref point used for mapping India known to this day.

Additional Notes

• To measure location the ellipsoid matches area of concern
• The horizontal datums have different local types in the sphere.
• Earth measurements are performed above / below water.
• Earth used to measure elevation of the different surfaces.

Ellipsoid

• Ellipsoid area when shape is made.
• Small axis & Ellipsoids will creates spherical points.

Orthographic height

• Orthographic = Ellipsoid - Geoid levels.
• Ellipsoidal altitude (GPS position)= position from ellipsoid section or horz section is constant in is location.

Geo-Referencing

• Geo-referencing process assigns spatial coordinates to spatial data using a coordinate system.
• Assign the spatial coordinates and overlay current information.
• Geo-referencing is to the spatial world to show characteristics or designs.
• Create data between surface of earth and GEO spatial information.

2D dimension is approaches.

• Easisest way is connect map locations with known area.
• The two design systems make a function for this connections.
• Its connected by various linear functions, with known variables.
• This design requires various parameters.

Additional notes to 2D coordinates

• Once the coordinate system is know map coordinates are calculated.
• Geographic and measurements take 2 step locations • selection of system to use for this location • setting and knowing the various parameters.
• These design types relate mainly to sensor design.
• This is for Aerial use in flat planes.
• Transformation and can easily to 1st or 2nd design.
• 1st part is the easiest for these types

Spatial Coordinates

• Coordinate maps with imagery or x and y location.
• Equations here need six known variables.
• Then, you can determined the values.
• Examples is water structures to align with GPS signals.
• To find designs with little change use three of area to ensure quality..

Additional points-

• Listed known area with its spot on a map.
• Software calculates a squares in known points..
• To verify data is measured against the coordinates.
• The difference in the overall quality is listed in ROOT form.
• This used for the dimension qualities.

Transformation quality

• Projection used can be found using standard coordinates
• These spots may reflect corners/ interstates.
• Image location can vary by shape.

Tranformation Points

• These can make changes by altering design.
• The change effects with errors in information
• If too many correction must be performed on a data set
• Then design should re-analyzed or rechecked.
• Linear alignment can be used to rectify linear offsets.

Rectification

• Rectification involves geometrically correcting an image, enabling it to be represented on a planar surface and conform to maps.
• This process is necessary for accurate area, distance, and direction measurements.
• Achieved by transforming data from one grid system to another using a geometric transformation.
• Establishes mathematical relationships between pixel addresses and corresponding coordinates.

. Spatial Interpolation has many characteristics.

• Its locates position and the XY spots. • Applied to initial position and image quality or design.

• This involves choosing ground control points.

Other factors must equal to be meet.

• Image brightness to equal • Pixel must show change in brightness depending on the column and what its recording to be located. • These qualities must be understood to accurately measure change.