If you look at Montana in web Mercator projection in ArcMap 9.3, the measure tool will tell you the length of the international boundary is 830 miles. Web Mercator is totally inappropriate for use in GIS applications. The only reason to use the web Mercator projection for Montana applications is the ease of mashing up with all pretty base maps in that projection. The scale of the web Mercator projection at Plentywood is 8 percent greater than the scale at West Yellowstone, and it makes the state look wrong. I think web Mercator is a poor choice to use for an application designed to focus on one region the size of Montana. Go to, pan from Alaska to South America, and watch the scale bar change.
#GOOGLE MAPS MONTANA SOFTWARE#
The Web Mercator projection is OK to use in web applications where you want to be able to zoom in close to any place in the world and the software understands the change in map scale as you move north and south. The planar distance could be wildly inaccurate if you are using an inappropriate map projection (such as web Mercator). ArcMap was incapable of doing that before version 10, and you still have to know to ask it for geodetic distances (or work in latitude/longitude coordinates) rather than planar distances. When you use the ruler in Google Earth to measure a distance, it gives you the true geodetic distance.
I'm sure there are many ways to abuse Google Earth, but the coordinate system it uses isn't one of the concerns. This is similar to a pure WGS84 projection, but is a Projected rather than Geographic projection. Not sure about this one, but from what I can gather if you are creating an OGC WMS service then you need to use the WGS84 World Mercator projection (EPSG code of 3395). Esri provides a transformation to move between the two. This projection is non-spherical (and thus unlike the Google Maps projection). Google Earth uses a WGS84 geographic projection with an ESPG code of 4326. Google Maps recognizes this code in a mashup. In the release of 9.3.1 and 10.0 SP1 ESRI reversed itself and went back to publishing the 3857 EPSG code as 102113 (the original temporary code). In the release of 10.0 ESRI published the EPSG code of 102113 or 102100 as the official code of 3857. In ArcGIS Server 9.3 map services ESRI published the EPSG code of either 102113 or 102100 depending on which map projection was used. EPSG 102113, 1021 are supposed to be absolutely identical projections, but the latter is official and the formers are not.
#GOOGLE MAPS MONTANA HOW TO#
Apparently they learned how to play nice in the past 18 months.ĮPSG 3857 is supposed to be the best for mashups. 102100 were temporary codes as the official governing body was playing hardball with Google and others - saying that their projection was not a real projection and pretty poor science and math. Last year 102113 was changed to 3857 and adopted as the official EPSG code. This was later changed to 102100 for the Web Mercator Auxiliary Sphere, which was more of a sphere than 102113. I am currently using a spatial reference with a EPSG code of 102113 for ArcGIS Server map services that are to support mashups with Google Maps. I'd appreciate any corrections to my investigations.
#GOOGLE MAPS MONTANA FULL#
Found a lot of information, but had to piece together the full story. Remote mountain property for sale in montana.I spent a couple of hours researching the Google Maps and Google Eart projection question.
0 kommentar(er)
