1. Cartography Basics *Map Projections *Datums *Coordinate Conversion *Modtran *Resampling

2. Map Projections * Spherical earth model Latitude, Longitude, Altitude * Meracator Projection *Universal Transverse Mercator (UTM)Projection zone, easting, northing, altitude * UTM Military Grid * Global Coordinate System (GCS)

3. a b DATUM WGS 84 Semi-major axis = a = 6378137.000m Semi-minor axis = b= 6356752.314m Flattening =f 1/f = (a-b)/a = 1/298.257223563 Geodetic latitude DATUMS

4. DATUM TRANSFORM Lat/long/alt in datum 1 Same Lat/long/alt in different Datum The same lat/long/alt numbers in two different datums refer to two different points on the earth. A Datum Transform converts the same point on the earth from lat/long/alt in one datum to lat’/long’/alt’ in second datum. Same earth point has different lat’/long’/alt’ in a different datum

5. a=semi-major axis 1/f = reciprocal of flattening

6. Coordinate Conversion Projection 1 Datum 1 Projection 2 Datum 2 Easting= E(lat,long,alt,datum_parameters) Zone= Z (lat,long,alt,datum_parameters) Northing= N(lat,long,alt,datum_parameters) Alt= A(lat,long,alt,datum_parameters) long lat Zone, Easting

7. Modtran execution EXAMPLE

8. Resampling Projection 1 Datum 1 Projection 2 Datum 2 V(Easting,Zone, T(V(lat,long,alt,datum_parameters), Northing, Alt V(lat,long,alt,datum_parameters), datum_parameters) V(lat,long,alt,datum_parameters), V(lat,long,alt,datum_parameters)) long lat Zone, Easting

9. Resampling Algorithm 1) Get point of interest P 2) Transform to coordinates P’ =T(P) in which data is available 3) Find surrounding data Values V(P’+1),V(P’-1) 4) Interpolate from surrounding values to the Value at the transformed point V(P’) = I(V(P’+1),V(P’-1),…) 5) Assign the interpolated value to the point of interest V(P) = V(P’)

10. Interpolation *Nearest neighbor *Truncate *Bilinear Interpolation X X+1 Y Y+1 X’,Y’ V(x’,y) =V(x,y) + {V(x+  x,y) - V(x,y)}(x’-x)/((x+  x )-x) V(x’,y+1) =V(x,y+  y ) + {V(x+  x,y+  y ) - V(x,y+  y )}(x’-x)/(  x ) V(x’,y’) = V(x’,y) + {V(x’,y+  y ) - V(x’,y’)} (y’-y)/(  y )