1. Mapping Fundamentals Appendix A Nate Bowers Spring 2010

2. Latitude and Longitude Effective use of Lat/Long is key to making worthwhile Google Maps Decimal Degrees -96.012778 96.012778 W DMS –degrees/minutes/seconds -96° 0’ 46” -96 0 46 96 ° 0’ 46” W Recognize when a conversion needs to be made

3. DMS Conversion Converting from DMS to Decimal Converting from decimal into DMS Google Conversion Online Tools

4. Coordinate Precision

5. Use JavaScript to maintain precision: – The toFixed built-in function “converts numbers to strings with the given precision” (p.315). – The toUrlValue “creates a string containing the coordinates, separated by commas and formatted with the given precision” (p.315).

6. Calculating Distance The curvature of the Earth complicates true distance. The distancefrom built-in function in JavaScript can help:

7. http://commons.wikimedia.org/wiki/File:Tissot_indicatrix_world_map_equirectangular_proj.svg http://commons.wikimedia.org/wiki/File:Tissot_indicatrix_world_map_Mercator_proj.svg Equirectangular Map Projections

8. Google Maps uses a Mercator Projection – Nothing >85° N/S – Distortion is reduced over small latitude ranges – The higher the zoom, the lesser the distortion Mercator is a square map – Simplifies conversions between pixels and Lat/Lng – Simplifies tiling ZoomTiles 01 14 216 364 4256 51,042 64,096 716,384 865,536 9262,144 101,048,576 114,194,304 1216,777,216 1367,108,864 14268,435,456 151,073,741,824 164,294,967,296 1717,179,869,184

9. 2 miles

10. Sources Udell, Sterling. Beginning Google Maps Mashups with Mapplets, KML, and GeoRSS. 2009, New York. 313-324 Wikipedia – http://commons.wikimedia.org/wiki/File:Tissot_indicatrix_worl d_map_equirectangular_proj.svg http://commons.wikimedia.org/wiki/File:Tissot_indicatrix_worl d_map_equirectangular_proj.svg – http://commons.wikimedia.org/wiki/File:Tissot_indicatrix_worl d_map_Mercator_proj.svg http://commons.wikimedia.org/wiki/File:Tissot_indicatrix_worl d_map_Mercator_proj.svg Google Maps – http://maps.google.com http://maps.google.com