Editing DSP
From BRL-CAD
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Example 1. | Example 1. | ||
− | In | + | In mged create a dsp object: |
mged> in dsp1.s dsp f Ex1.dsp 142 150 0 ad 1 0.005 | mged> in dsp1.s dsp f Ex1.dsp 142 150 0 ad 1 0.005 | ||
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Finally, create the dsp file: | Finally, create the dsp file: | ||
− | $ asc2dsp t-reversed.asc t. | + | $ asc2dsp t-reversed.asc t.sp |
(The TGM creation is left as an exercise for the reader.) | (The TGM creation is left as an exercise for the reader.) | ||
− | === A practical example | + | === A practical example [UNDER CONSTRUCTION] === |
− | Now let's consider a more practical example and a real test of BRL-CAD. We can import topological (topo) data and produce a realistic ground surface. There are many free sources of such data, but | + | Now let's consider a more practical example and a real test of BRL-CAD. We can import topological (topo) data and produce a realistic ground surface. There are many free sources of such data, but this, for US topo data, seems to be the most likely: |
− | http://nationalmap.gov/viewer.html | + | http://nationalmap.gov/viewer.html |
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− | + | For now, though, the format for the data is not easily found so we located another source of topological data (digital elevation models [DEM]) in [http://mcmcweb.er.usgs.gov/sdts/ SDTS] format: | |
http://data.geocomm.com/dem/demdownload.html | http://data.geocomm.com/dem/demdownload.html | ||
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[http://data.geocomm.com/catalog/US/61076/1231/index.html El Paso County], and [http://data.geocomm.com/catalog/US/61076/1231/group4-3.html Digital Elevation Models]. | [http://data.geocomm.com/catalog/US/61076/1231/index.html El Paso County], and [http://data.geocomm.com/catalog/US/61076/1231/group4-3.html Digital Elevation Models]. | ||
− | On that page we downloaded all six 10-meter data archive files | + | On that page we downloaded all six 10-meter data archive files because we were not yet sure which one we wanted. We also downloaded the six *TXT files which contain metadata about each archive. [Note that you are required to have a Geo Community account for any downloads (membership is free).] |
The six archive files are: | The six archive files are: | ||
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4057865.DEM.SDTS.TAR.GZ | 4057865.DEM.SDTS.TAR.GZ | ||
− | + | Note that taking the first archive as an example: | |
$ tar -tvzf 3818122.DEM.SDTS.TAR.GZ | $ tar -tvzf 3818122.DEM.SDTS.TAR.GZ | ||
− | we see that the archive files are not in a directory | + | we see that the archive files are not in a directory, so we create a directory for each: |
$ mkdir 3818122.dem | $ mkdir 3818122.dem | ||
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http://www.visualizationsoftware.com/3dem | http://www.visualizationsoftware.com/3dem | ||
− | In order to | + | In order to examine the data in SDTS files there are two directions to take: (1) use a [http://mcmcweb.er.usgs.gov/sdts/sdtsxx/index.html government supplied library] or (2) use the [http://gdal.org/ GDAL library]. We chose both because they both have useful utility programs. |
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− | + | To help select the data to be used we put pertinent metadata into a spreadsheet to calculate delta altitudes and to easily compare min and max altitudes as well as the lat/long boundaries of each data set. |