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12

Update: I think wget would be better, i just don't use it very often: wget -r -A.zip http://dds.cr.usgs.gov/srtm/version2_1/SRTM3/ Also see for some retrieval wait options (if you want to be courteous): http://superuser.com/questions/178297/wget-terminates-unexpectedly/178326#178326 You could curl the files with a little bit of text editor work. For ...


9

For a local solution, GRASS can be scripted to do this: # extract raster values at our points # use cubic convolution for interpolation between DEM locations v.drape in=my_pts out=pts_srtm_elev type=point rast=srtm_dem method=cubic I ran an extended version of this for one of my use cases and performance of v.drape was no issue at all.


7

Download the source code from here http://www.osola.org.uk/elevations/index.htm SRTMGeoTIFFReader.php is the clever file the reads the GeoTiff and converts the elevation values (in meters) into Lat/Lng coordinates. I doubt this is exactly what you want but it does give you a solid base on understanding the process required to accomplish the task from your ...


6

Mike Migurski (of Stamen Design) recently made a major new open terrain map: details on his blog and I put up a quick map viewer for it. It does terrain relief shading with various DEM sources combined with roads, labels, etc from OpenStreetMap. The source code to generate the map is on GitHub.


6

TopOSM has terrain tiles - though limited coverage (US Only) http://www.toposm.com/us/ Full Details http://wiki.openstreetmap.org/wiki/TopOSM All the Rendering and Source files are available http://svn.openstreetmap.org/applications/rendering/toposm/ License is the same as Open Street Map OpenStreetMap Data is available under the Creative Commons ...


6

Data format I'll take it as a little exercise in how to program a data reader. Have a look at the documentation: SRTM data are distributed in two levels: SRTM1 (for the U.S. and its territories and possessions) with data sampled at one arc-second intervals in latitude and longitude, and SRTM3 (for the world) sampled at three arc-seconds. Data are ...


5

You can generate your own using Maperitive: generate-relief-igor command generate-tiles command A sample hiking map using such tiles.


5

A few thoughts: A previous answer correctly recommends resampling during display to smooth out the irregularities in the hillshade. This is primarily used for cartographic effect when you are finishing a map. Use the Image Analysis window to run a 5x5 smoothing window over the image Find better elevation data. 10 m NED Data is available for the ...


4

http://dds.cr.usgs.gov/srtm/version2_1/Documentation/Continent_def.gif You can use http://www.latlontoelevation.com/ lat/lng to get the Shuttle Radar Topography Mission (SRTM) data too.


4

SRTM data is easy to download for a given area, I've use this site in the past. The files aren't huge, and you can get them as georeferenced TIFFs. Downloading the whole world might take a while, but a couple of tiles covers a pretty large area. The issue you might have is with horizontal resolution, which is about 90 metres for most of the world, and the ...


4

The interpolation modules in GRASS can work with a line vector, such as contour lines, to create a DEM raster. So you could create a DEM raster from your contour lines, then "correct" the ASTER GDEM with this data. The catch will be in matching elevations from the contour-based raster to the ASTER GDEM, to avoid a terrace effect at the edge. The procedure ...


4

When you downloaded the data what format did it come in? By definition, if the data is a raster format, it can be considered 3D data, as it has a x,y,z value. If you are looking to have it extruded in ArcScene then you will want to do a few of the following things. Assuming your data is in a usable raster format (ie: GeoTiff) then you will want to do the ...


4

I suppose that it is the result of r.shaded.relief. Have you set the correct resolution of your region of work (resolution of the SRTM layer, Res: 59.74514451 here) ? Resolution of the SRTM layer: Resolution of the region: Elevation; r.shaded.relief without grainy surface with the correct resolution


4

SRTM (Shuttle Radar Topography Mission) was a shuttle mission, no satellite involved. But essentially the satellites do not cross the poles. In a geosynchronous orbit, which most imaging satellites are in, you get a pattern like: This great because it means that the orbit can be timed and most parts of the earch get covered at around noon, so good ...


3

The "Marmota" project at FBK, Trento, Italy, is offering the functionality you seem to aim for: http://tev.fbk.eu/marmota/ There are a series of publications available on that site. Furthermore, see the related question here.


3

It sounds like you need this as a generic solution, i.e. having all the world's elevation data available to you for any track you want to process, hence not wanting to store all the CGIAR data locally; the gpsvisualizer.com mentioned above (@Llaves) may be your best bet. If you don't need high resolution, the GTOPO data set (1km grid) is only ~300MB for the ...


3

You can use Maperitive to download SRTM tiles automatically and unzip them. Just zoom in/out to the area of your interest and it will download all the required tiles to your disk. And best of all, it's free. Here's a sample hillshading + hypsometric rendering generated using SRTM tiles in Maperitive:


3

The length of the arrows is determined by the magnitude_map (which would usually be the slope). If you want the arrows to be of uniform length, you can just create a new map of ones (r.mapcalc ones=1) and use that as the magnitude map. You can then control the length of the arrows using the scale factor: d.rast.arrow map=aspectMap skip=50 magnitude_map=ones ...


3

The folks at telascience are starting to revive the OpenAerialMap.org project which is on hold for now. They have already processed NAIP which can be found at http://hyperquad.telascience.org/naip/ They also have world coverage of Landsat done. As far as contours, elevation, shaded relief, etc, part of the plan is to include SRTM http://srtm.csi.cgiar.org/ ...


3

We had good results with this approach: Convert original raster DEM (90 meters) to points Interpolate points to a new raster (finer resolution e.g. 10 meters) Create hillshade from new raster (step 2). It was a few years ago - so I can not remember the parameters exactly. But I guess we used a spline interpolation. Spline produced very soft surfaces. ...


3

I would create a virtual raster with both images. You can do it in Raster > Miscelaneous > Build Virtual Raster (Catalog). It will be a quite small file that will allow you to open both images at the same time in QGIS, and set blending to them globally. That way the overlapping blending mode or transparencies won't show. Two overlapping images with ...


3

An improved version of SRTM data can be obtained from http://www.viewfinderpanoramas.org/. Coverage can be looked up under http://www.viewfinderpanoramas.org/Coverage%20map%20viewfinderpanoramas_org3.htm The creator has put special emphasis on manually filling the error on icy parts of the world as described here: ...


2

The Natural Earth 1:10m data is a good place to start, but not at the resolution of the Google Maps terrain data. If you can deal with a medium resolution dataset, then styling something like the 250m SRTM data isn't too bad, but if you're interested in something at a higher resolution, it may be worth contacting the OpenCycleMap folks and see if you can get ...


2

Do you mean 3 arc-seconds? That indicates LatLong. You will have to create a GRASS location with UTM or Lambert LAEA/LCC or another metric coordinate system and run r.inund.fluv therein. See also "GRASS GIS projection intro".


2

By default, arrows are drawn at the size of a cell and cannot be seen if the raster map is relatively close in scale. You can use the skip option to draw arrows every n-th cell in both directions if you are working with relatively high resolutions. It may be useful to disable the grid in this case, which is accomplished by setting its color to "none", i.e. ...


2

There is a command that do just what you want: v.what.rast "Uploads raster values at positions of vector points to the table" You need a vector file with points and a table attached to it. In the table you need to create a column to receive the values from the raster. Then run v.what.rast. It will read the raster value in the position below each point and ...


2

First you should specify what kind of horizontal/vertical precision you would be satisfied with. But let's look at this from a practical perspective: Each SRTM3 tile has 1200x1200 cells, each cell is a two-byte integer value representing the elevation in meters. That's around 2.75 MB of raw uncompressed data. There are 14042 SRTM3 tiles. That's cca. 38 GB ...


2

Another one is Closed Contour Maps http://www.closedcontour.com/ blog about it last week: http://mapperz.blogspot.com/2011/03/closed-contour-sps-maps.html (blog post relevant to GISse question not self-promotion)


2

I do it this way: I download srtm data from : http://srtm.csi.cgiar.org/SELECTION/listImages.asp Also, I just checked, use ftp to download, its a lot faster than http. Then load it in Global Mapper, re-project in to desired coordinate system and export as 32 bit floating point elevation data. (yes its that simple, 2 min job at max). I tried in ArcMap and ...


2

Here's what the original NASA's SRTM document says (emphasis is mine): File names refer to the latitude and longitude of the lower left corner of the tile - e.g. N37W105 has its lower left corner at 37 degrees north latitude and 105 degrees west longitude. To be more exact, these coordinates refer to the geometric center of the lower left pixel, ...



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