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New NorthEast TOPO maps at GPSfiledepot...

Just noticed they have them on their site, downloaded it and there are differences in my area at least to the other TOPO download on their site. Loading them now on the my Nuvi 500.

Comments

  • lordgrinz 0 Points
    There are definitely more contour lines for my area, which is a plus! :)
  • Marc 301 Points
    Did they get the roads right? In the Topo 2008 they were off up to 100s of yards. Wouldn't mind having this but would also like the roads to be accurate.
  • Boyd 1985 Points
    Almost all of the free Garmin maps will use TIGER road data - see:

    http://www.census.gov/geo/www/tiger/tigerua/ua_tgr2k.html

    Google will find more about TIGER if you're interested. I made a map of Southern New Jersey myself which incorporates this data, and for the most part it appears to be quite accurate.

    Also realize that Garmin's City Navigator maps may not be any more accurate and you won't likely even notice because they use "road lock" to snap your car's position to the road. The Garmin US Topo 100k maps don't support road lock.
  • lordgrinz 0 Points
    Give us coordinates and maybe we can check it for you, but I havent seen anything wrong yet.
  • Marc 301 Points
    Almost all of the free Garmin maps will use TIGER road data - see:

    .
    I am not sure were they got the data from for the Topo 2008 but it is definitely worse than the current city Naviigator, the free Ibycus street maps, and even my old Magellan contour maps. I don't think they were based on on the most recent Tiger data. When I talked to Garmin they said since it was for hiking and off road use so they weren't that concerned about the road accuracy. When I go home tonight I'll pull up some comparisons to post.
  • Boyd 1985 Points
    If you read my post and lordgrin's more carefully you will see we have been talking about free user contributed maps at GPSFileDepot.com and not Garmin US Topo 2008...
  • Marc 301 Points
    My bad. Did not even know what file depot was. Just thought it was an online store.
  • Boyd 1985 Points
    Check out their free topo maps. You may like them better than Garmin's :)

    http://www.gpsfiledepot.com/
  • Marc 301 Points
    I already have and the maps are superior to Topo 2008. The roads on the New England Topo appear to be identical to those from the Ibycus USA series, which are quite accurate. If I can figure out how to post images I'll post some images that show the differences.
  • Boyd 1985 Points
    As I said, almost all of the user-created maps use TIGER street data.
  • Marc 301 Points
    So here's a comparison of street accuracy for City Navigator
    image

    New England Topo
    image

    and Garmin Topo 2008

    image

    Note how far off the waypoint is for Topo 2008. Apparently this problem has been in Garmin topo maps for a while, they just don't care enough to fix it, according to the conversation with their tech support when I first purchased the maps. Probably the worst 80 bucks I spent in a long time. The new home made are superior in street location and contourinformation! As for the accuracy of the acutal intersection layout, it is not quite what City Navigator drew, nor quite what New England Topo drew, but about half way in between.
  • lordgrinz 0 Points
    I compared those with the satellite imagery, and seems you are right, and the TOPO's from GPSFileDepot are better than Garmin's own Street info. I like the new maps, only thing I would wish for would be if they could add buildings/homes to the maps. Is that even possible? But in either case the added contour lines are REALLY NICE! :D
  • Boyd 1985 Points
    I doubt that you'll see buildings or any detail of that nature on a Garmin unit using the current vector format. Aside from the huge job of creating the maps, the file size would be unmanageable. I created a very detailed map of the southern half of New Jersey and used landcover data with custom textures to make a more graphic topo map. The file size is about 200MB - and this is just half of a very small state.

    image

    The Oregon, Colorado and Nuvi 500 are capable of using raster-based maps, so maybe we will eventually see aerial photos or real USGS quads on them someday? Actually, I see that somebody did do a little project with building footprints for a few areas in the Northwest:

    http://www.switchbacks.com/maps/Buildings.html

    There are some great things about Garmin's vector-based format, but you should probably look at other brands if you want real USGS maps or satellite imagery. The Magellan Triton and DeLorme PN-40 can do this, and you can also run OziExplorer CE on a WIndows CE based GPS if you want to "roll your own" (like me :) )

    As far as map accuracy goes (and I am certainly not defending US Topo, because I agree it's not so great), zooming in to the 80 foot level is certainly exceeding the accuracy limit of both the map and your GPSr. In fact, Mapsource is telling you this by displaying overzoom under the map scale. Zoom back out until that disappears, and although the error will still be present, it will not look so extreme.
  • lordgrinz 0 Points
    Boyd, that link is what I would love to see done, but then we are really just trying to imitate the USGS maps. If they add this or the USGS for my Nuvi 500 I will have everything in one unit, that would be awesome! :D
  • Marc 301 Points

    As far as map accuracy goes (and I am certainly not defending US Topo, because I agree it's not so great), zooming in to the 80 foot level is certainly exceeding the accuracy limit of both the map and your GPSr. In fact, Mapsource is telling you this by displaying overzoom under the map scale. Zoom back out until that disappears, and although the error will still be present, it will not look so extreme.
    Of course if you zoom out the error looks smaller, but at this scale it makes it obvious that the road placements on the Topo 2008 can be off by hundreds of feet as I have personally experienced. Indeed this is over zoomed, but it still accurately depicts the error in each case. As far as my GPSR, most of the time I would say its accuracy is within 80 feet. While hiking and trying to find a fire road I used to switch to the Ibycus maps because I could never trust the Topo 2008. Now with the New England Topo maps I have some faith that they are reasonably accurate.
  • Boyd 1985 Points
    Like I said, not trying make excuses for US Topo. I have also experienced errors of the same nature. However Garmin's map format only provides for a maximum precision of 24 bit coordinates, which translates into about +/- 2.5 meters. And the spec on most of Garmin's GPS'es only calls for 10 meter precision. So, while I understand you are only trying to illustrate your point, 80 feet is a pretty extreme zoom level.

    Lordgrinz: sounds like it's time for you to start making your own maps. :D There's a truly amazing amount of shapefile data available out there to do whatever you want. Mapwel is a pretty easy way to get started with all this:

    http://www.mapwel.biz/

    It can create maps from raster imagery, but personally I wouldn't bother with that as it is only a hack with lots of limitations. But it can import shapefiles which you will find on GIS sites at all levels of government.
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