Custom maps vs USGS

[weamish]

I'm looking at a DeLorme GPS, which includes 7.5 minute series (1:24k) USGS maps. Wondering if I'd be better off with a Garmin, using the gpsfiledepot custom WA map. Any idea how the two maps compare?

Thanks!

Steve

[Boyd]

The maps that we make here will never be the same as "real" USGS maps which were drawn my hand and include lots of little details that make them unique. With my map of New Jersey, I tried to copy the USGS style as closely as I could, but it's still not the same kind of thing. For example, the USGS quads are pretty old and may show historical sites that no longer exist but might be of interest to explorers. I don't think you can really compare them to Garmin vector-based maps.

But if you want the real USGS 24k topo's, Garmin has just introduced a service for them at $30/year for unlimited downloads. There are having issues with their servers though, so you may have to wait before it's fully up and running. See: http://gpstracklog.com/2011/06/garmin-birdseye-topo-us-screenshots.html

These should be the same as the DeLorme USGS topo downloads, although I believe DeLorme also gives you access to vector based 24k topo's. Since this site only supports Garmin, it's probably not the right place to find an objective comparison though.  

If you are curious about the WA topo from here, just download it and see for yourself. It will work on your computer in Mapsource without purchasing anything.

[weamish]

Thanks Boyd. Wow, it looks like Garmin is finally starting to compete on map pricing. No longer any need to spend big bux on the regional DVDs?

If we can get a $30 subscription from Garmin, does that affect the need for the custom state maps posted here?

[maps4gps]

What Garmin recently called 'custom maps' are raster images.  These are colored pixels of a specific cell size or scale.  Zoom in too much and the image gets blurred (no additional info added); zoom out too much and thing merge.  Their max and min zoom display is related to the pixel size of the image.

Map authors have used the term 'custom map' for years to denote vector maps not produced/sold by Garmin that will work on Garmin GPSrs.

USGS has only produced/released digital line files with all the 'features' for about 4% of the 24k quads.  There is no public source(s) for all the info types on a 24k topo.  In some cases we add features which USGS does not include on the 24ks. 

Only you can judge which would be better.  Likely the best would be to have both on the GPSr and be aware of the limits of each. 

[Boyd]

Are you familiar with the US Topo Project? I am anxious to have a look at these but haven't gotten around to it yet. http://nationalmap.gov/ustopo/index.html

US Topo is the next generation of digital topographic maps from the U.S. Geological Survey. Arranged in the traditional 7.5-minute quadrangle format, digital US Topo maps are designed to look and feel like the traditional paper topographic maps for which the USGS is so well known. At the same time, US Topo maps provide modern technical advantages that support wider and faster public distribution and enable basic, on-screen geographic analysis for all users.

Maps4gps is correct about the limits of raster imagery, it is only useful within a limited scale of zoom levels. If the map is made properly, when you zoom in far enough for it to break up you have exceeded the resolution of the map anyway. It is more of a problem when want to zoom farther out, because you can't read the names of roads and towns.

But many people think these maps are the "holy grail", and I can understand that sentiment. There's just something special about a hand-drafted map. I think there are certainly still valid uses for Garmin's 24k products though. For one thing, they have pretty high resolution DEM data that can provide 3d views and shaded terrain, as well as elevation plots. Also they have routable  NAVTEQ roads which tend to be pretty accurate plus a rich set of POI's for things like stores, restaurants, gas stations, etc.

The important thing is that Garmin users now have a lot of options between custom maps they can easily make themselves, free maps from here and other sites, Birdseye aerials, Birdseye 24k USGS topo's, City Navigator, Garmin 100k topo's and Garmin 24k topo's.