Gang, Joseph Elfelt turned me on to MyTop.com's (somewhat hidden) public, free map service that can easily be integrated into a Google Maps mash- up. It doesn't suffer from the EPSG:4326 mapping problem TerraServer has, and the maps are infinitely more beautiful. Here's an example:
http://www.vulgarianramblers.org/peak_detail.php?peak_name=Morgenson&show_google_map=true The following MyTopo.com web page explains their terms of service and documents the API: http://www.mytopo.com/google/index.cfm Finally, the JavaScript file they offer up as an integration tool can't handle deferred (AJAX-style) loading of the Google Map APIs, so I rewrote this code. You're free to download an use my JavaScript file, but please don't just point to the one on my server: http://www.vulgarionramblers.org/javascript/mytopo_gmaps.js Enjoy, - Chris On Oct 21, 8:02 pm, Chris Schneider <[email protected]> wrote: > DearTerraServerGurus, > > I'm having trouble with my Google Maps/TerraServer"mash-up" where the > latitude and longitudes passed toTerraServerdo not seem to be > converted to UTM coordinates with sufficient precision (off by > approximately 100 meters). > > I'm using a method several other Google Maps API users have described > (e.g.,http://tinyurl.com/yzvl6gr) to integrateTerraServer'sDRG > tiles as an option (map type) within a map displayed by Google Maps. > Among other things, this method passes &REQUEST=GetMap and &SRS=EPSG: > 4326 tohttp://www.terraserver-usa.com/ogcmap6.ashx. Although the > resultingTerraServerDRG map type (TOPO) displays the USGS DRG image > and responds to the Google Maps scale controls, points displayed on > TOPO appear to be approximately 100 meters south and 50 meters east of > where they appear on the Google Maps types (e.g., Terrain). > > For example, here's a test page from my web site that attempts to > display a map approximately centered on the summit of Mt. Whitney in > California (with a marker on this location), which (according > tohttp://tinyurl.com/ykd8edj) is at longitude, latitude (-118.2934244, > 36.5782684): > > http://www.vulgarianramblers.org/whitney_test.php > > If you increase the magnification and then compare the location of the > marker in "TOPO" mode vs. that in "Terrain" mode, you'll notice that > the former is approximately 100 meters SSW of the true summit. More > importantly for my application, the TOPO location is approximately 100 > meters SE of the Terrain location. > > I wanted to test theTerraServerEPSG:4326 projection support outside > my application, but unfortunately latitude and longitude coordinates > entered directly into the web interface athttp://terraserver-usa.com > are apparently "gridded" to nearby locations. For example, when I > enter (-118.2921002, 36.57871135) into the Longitude and Latitude > boxes on this page, the GO button displays a map that is centered on > (-118.27879, 36.59925) instead, at least according to the values now > displayed in those boxes. As I change the resolution of the map, the > coordinates displayed in the boxes change again (as does the location > appearing in the center of the map). This is apparently due to the > tiling of the source data, but it effectively prevents me from testing > coordinates to a resolution within 100 meters. > > I am aware of the inherent difference between the projection & datum > used for NAD27 UTM coordinates vs. those for WGS84 latitude/longitude > pairs. I also understand that the USGS DRG tiles provided > byTerraServeroriginate from USGS maps using UTM projections. I would > prefer to pass UTM coordinates toTerraServer(so that it didn't have > to take the time to convert from EPSG:4326), but the Google Maps mash- > up apparently requires me to use EPSG:4326 latitude and longitudes. > > Any help would be greatly appreciated. > > Thanks, > > - Chris -- You received this message because you are subscribed to the Google Groups "Google Maps API" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-maps-api?hl=en.
