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Messages - dcana

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Map Making Support / Re: problems at step #2 of Dan's instructions
« on: July 11, 2013, 07:21:46 PM »
Even with the new USGS NED server, you may still have to turn the DEM files from a supplied format (like flt) to tif for DEM2TOPO. I used a batch file I got at the USGS, which in turn requires and installation of the gdal utilities.  Much of the instructions were written when the USGS seamless server supplied tif (Geotiff)-- that server is mainly gone.

I'm using this process for areas outside the USA, where the are no good topo maps, or the available maps are off.  I've even found places in Nevada where the available garmin-compatible maps are off. I'm also interested in some of the newer data, which may resolve some massive errors in the USGS database.

Where are the flt files?  In the group of files that I downloaded, the one large file (465MB) has an adf extension.


Map Making Support / Re: problems at step #2 of Dan's instructions
« on: July 11, 2013, 07:12:51 PM »
What's the advantage of doing an oil painting when you can just download a copy of a Rembrandt masterpiece? What's the advantage of learning how to play the guitar when you can just download a copy of a Jerry Garcia performance?  ;)

Seriously, you get the idea. The advantage is that you increase your knowledge by learning a new skill, you can express your own creative ideas and you can share them with others.

Are you you asking which is simpler? Download the Rembrandt. Probably, you will never be able to do any better yourself.

To get a little more technical, USGS quads are raster imagery (scans of paper maps). The map in the tutorial is a vector based map. Both formats have advantages and disadvantages. Raster imagery is only viewable within a very limited range of zoom settings - gets all blocky if you zoom in too far, becomes a black blob if you zoom out too far. Vector imagery offers control over what features show at different zoom levels and lineweights remain constant.

But scans of USGS quads have a very different quality since they were hand-drawn. And the often have many little details not found on vector based maps. Each type of map has its uses.

BTW, if you want USGS quads, I think Garmin Birdseye Topo is a no-brainer. Unlimited downloads of USGS quads (plus Canada) for $30. Lots easier than downloading and processing the USGS stuff yourself.

I agree.  It's great to be able to create maps to your own specifications and to increase your knowledge, etc., plus it's just very satisfying to do so, but I was just wondering if maps created this way have any real advantage - for example, being routable.  I assume they're not routable as so very few of the maps that people have uploaded are.  Can you see an elevation profile of a proposed route?  I have read some about the advantages/disadvantages of vector maps versus raster maps.  One of the advantages of vector maps is that they take up less space.  This general rule doesn't seem to hold in this case.

Thank you for the help

Map Making Support / problems at step #2 of Dan's instructions
« on: July 11, 2013, 04:04:55 PM »
Hello.  Noob here with some stupid questions.  I'm trying to create my first map using Dan's instructions.  First off, what's the advantage of doing this very time-consuming process with all its steps versus just going to various websites and downloading a topo of the area you need?  Is the resultant map somehow better?  Why not just download USGS quads, for example?

I am going to be using the free DEM2TOPO versus the $399 Global Mapper.  The first thing I did wrong is going to the National Map Viewer to download the elevation data.  I downloaded one 24k quad and, 365MB's later discovered that there is no tiff file to use with DEM2TOPO.  BTW, this download, which consisted of elevation data only, actually was more than 700MB of info unzipped.  Why so huge?  So if my state had 100 quads in it, that would take 70GB of information?  Wow.  I've downloaded 24k quads in pdf format and they were only about 30MB in size.  Anyway, if you are using DEM2TOPO how to you obtain the required file in tiff format?  As far as I can tell, you can't get it from TNMV and although the instructions under "Dem2Topo" say, "Make sure you used the USGS DEM LINK (GeoTiff) for Dem2Topo," above it says that "the seamless server is no longer operational."  Wha?

Any help, please?

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