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Started by dcana, July 11, 2013, 05:04:55 PM
Quote from: Boyd on July 11, 2013, 05:57:03 PMWhat'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.
Quote from: hwstock on July 11, 2013, 06:31:15 PMEven 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.
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