Map link inaccuracies

[Guest fiser]

I just hid a cache ("Valpo Vulcan Mind Box" (IN), it hasn't appeared on the site yet), and the MapBlast map for the area has a major highway approximately 1/4 mile out of place.

 

I noticed because I hid a cache North of a highway, and the MapBlast map shows the cache South of the highway. I went out and double-checked and my coordinates are correct. I've added a warning to the cache log.

 

Has anyone else noticed any MapBlast issues?

 

** I know we shouldn't rely solely on the maps, it's just that MapBlast would lead an unwary cacher to hunt in a cemetery!

 

[This message has been edited by fiser (edited 03-30-2001).]

[Guest bob_renner]

Interesting problem. I checked your cache page (GC59F) and MapBlast shows it south of the highway, but TopoZone shows it north of the highway. I think MapBlast uses NAD27 whereas the Geocache site uses WGS84. However, there isn't that much difference between these two at that location, plus, the difference should tend to move the cache north, not south. My guess is that the road is wrong on MapBlast. Check TopoZone and see if that matches your opinion of the cache location.

 

Bob

[Guest fairbank]

From the Mapblast FAQ:

 

MapBlast! uses the Datums of NAD83 for US and Canadian locations and WGS84 for the rest of the world. This is handy to know if you want to use latitude/longitude coordinates from your GPS for locating a MapBlast map or vice versa.

 

By the way, the differences between NAD83 and WGS84 is so small that it is basically negligible as far as entering or plotting coordinates in/from your GPS.

 

Eric

[Guest fiser]

Topozone shows the true location.

 

I'd hoped I could be a happy geocacher without learning the intricacies of the various formats, but I suppose I should start reading the "Units and Software" threads. Thanks for the info.