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To use the GRASS tools directly, you need to first import the data you want to work with into a GRASS database. If you use GRASS algorithms through the Processing toolbox, you can skip this importing step because Processing takes care of all the data conversion. It's therefore much more convenient. You don't have to explain to your students how GRASS works, ...


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Note that the g.region you used does not change the resolution of your raster layer. In general, what you do with the g.region function is setting the 'working resolution' and extent. In the case of your example, you are telling grass to use the extent of the raster layer my_raster and a resolution of 0.5. Functions will use that resolution rather than the ...


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-1.#IND returns when an incorrect mathematical operation is done, like dividing by zero or the square root of a negative number. Maybe GRASS tool used standard deviation of NoData set as -9999. I suggest two solutions: Check your source NoData value, if it is negative, change it to positive. If you cannot change it or if it's positive, you can convert ...


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Glad you solved - just as pointer for others: http://grasswiki.osgeo.org/wiki/Computational_region The easiest way to prepare for complete map export is to run g.region rast=TOAR_LC82260982013325LGN00_B1 -p So, set to the raster map name (or use the entry in the respective right mouse button context menu in the GUI to achieve the same).


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To check the number of points per grid cell from a LIDAR point cloud in GRASS you can use the r.in.xyz module. This module creates a grid from the point cloud using a "method" parameter by which you choose how to aggregate the points when importing. If you choose method=n then the resulting raster will contain a count of points for each cell. By setting ...


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You might like to use Fusion. It is a free software for point cloud processing and visualization . 1- Look into the manual for a command program called Catalog. It returns descriptive statistics from the point cloud. What you want is the Catalog's switch density:area,min,max. The manual description says: Creates an image for all data files that shows ...


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Well, technically it looks OK, but your are aware that you'll be creating almost 20,000 (!) rasters maps. Is that what you want?? You do not need to reset the resolution back to 1.125 at the start of each loop. Also, if all you want is to set a smaller resolution, why not try r.resample? It uses nearest neighbor, not IDW, but it might be good enough in ...


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in ArcGIS you can use equal to frequency for that. You can compute the number of times that the value of your stack of raster is equal to 200. It is recommended to create your stack in a vrt file (gdalbuildvrt) in order to avoid a huge files. As a remark, we did a similar work, you can visualize the products here and they are freely available on request. ...


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As for the second part of your question, v.build.polylines will connect line "segments", removing nodes as long as exactly two line segments are connected. All intersections with 3 or more segments will be left as nodes. I Can't help with the list of nearest neighbors.


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I faced a very similar problem a while ago: Unable to load 'nviz' through GRASS For me, downloading/installing WinGRASS-6.4.1 and running GRASS 6.4.1.exe seperately from QGIS worked. I was able to use nviz (after configuring the project location and mapsets etc). I still can't run it through QGIS for some reason but seems to work perfectly if I ...


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The Python processing module of QGIS uses the module subprocess to launch directly the GRASS commands with the script GrassUtils.py (in /.../plugins/processing/algs/grass/GrassUtils.py): 1) First it creates a temporary batch file (grass_batch_job.sh or grass_batch_job.bat) in /.../.qgis2/processing/ with the command (def ...


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Sort of depends where you are (which country) on what software and methods are usually used or are standardised on - some councils, state governments and governments have required methods. Also what sort of area are you looking at modelling ? Urban, rural ??? eg for Australia have a read of the www.arr.org.au site. They are in the process of releasing ...



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