GRASS GIS (Geographic Resources Analysis Support System) is a free, open source geographical information system (GIS) capable of handling raster, topological vector, image processing, and graphic data.

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comparison of atmopsheric correction methods

I have noticed that dos methods for atmospheric corrections are in the section of radiometric correction (i.toar) on grass gis.Does that means that dos is a method doing radiometric and atmospheric ...
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1answer
134 views

How to recategorize features in GRASS by geometry, like the ArcGIS Sort tool?

The ArcGIS Sort tool creates a new feature class with features sorted by geometry. For example, it can number features IDs from north to south, etc. Is there a way to renumber the cat field in a GRASS ...
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4k views

How to compute parameters for QGIS Affine transformation?

I have a vector floorplan (DXF) that I've added to a blank project in QGIS using the Dxf2Shp plugin. I've been reading tutorials and StackExchange threads, but I can't seem to find out how to ...
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46 views

Linearising aspect in GRASS GIS

After having produced aspect of surface in GRASS GIS and being aware that GRASS GIS calculates aspect counterclockwise from east, how could we transform aspect from being a circular variable (0-360 ...
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1answer
31 views

Mod function in GRASS GIS

What is the equal of ArcGIS Raster calculator "Mod" function (Finds the remainder of the first raster when divided by the second raster on a cell-by-cell basis.) in r. mapcalc in GRASS GIS?
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3k views

How to reclassify a float raster?

I have three rasters which represent distance (in metres) from certain things (bus stops, parks, libraries). I would like to reclassify these rasters so that they get integer values based on the ...
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57 views

Convert manual colored maps to vector

Is there a way to colorimetrically and automatically vectorize georeferenced rasters that came from manually colored, scanned maps? Currently we Print the topography maps 20k scale --> hand-coloring ...
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103 views

From Landsat spectral radiance (W/m2*sr*µm) to Global horizontal irradiance (W/m2) for mere mortals

We are working in a solar energy project to locate potential sites for solar panel farms. We are using the Landsat 7 panchromatic band to derive radiance with GRASS using i.landsat.toar (W/m2*sr*µm ...
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2answers
149 views

Use GRASS through R

I want to use GRASS GIS 7 through R 3.1.3 in kubuntu operational system. Could someone help me connect GRASS with R, and use GRASS commands through R (not the other way round!).
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1answer
104 views

topographic correction using GRASS 7.0 (**i.topo.corr**)

I would like to apply topographic correction using GRASS 7.0 (i.topo.corr). The imagery were already converted from DNs to Top-of-Atmosphere Radiances. When I apply the i.topo.corr command it runs ...
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74 views

Problem in running r.slope.aspect in GRASS

I am new to GRASS GIS, and have been trying to use the r.slope.aspect function to find out the slope, dx and dy rater map from an elevation map(512*512)[1]. But I am getting the following output: ...
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37 views

What logical function should i use to do a union of two raster files in GRASS?

The files are : DEM and roads. For the following i did euclid distance and then reclass. Now i need to know with what logical function to combine them elevation rank ...
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1answer
1k views

How to activate GRASS GIS 7 plugin in QGIS 2.8?

Apparently, my linux ubuntu setup of QGIS doesn't contain grass gis, although when I initially installed it last week I added grass gis to the command line. Anyway, I typed in once again and installed ...
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93 views

Problem in running r.sim.water

I am trying to run the r.sim.water in GRASS. I have calculated the partial derivatives dx and dy rater map using r.slope.aspect. I am using this elevation map [1] to get the time-series depth map. But ...
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24 views

GRASS watershed analysis add storm inlets

Try searching for this with no luck. I am using r.watershed to delineate flow directions, subwatersheds, etc. All good, except that storm drain inlets, culverts and subsurface drainage courses are ...
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87 views

Steiner tree problem: Optimal routes for Fibre planning on road network

I am trying to solve a large optimization problem where I have a set of nodes on a road network that need to be connected using fibre using the shortest possible amount of fibre. The problem is a ...
3
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1answer
81 views

How to add my own GRASS algorithms to Processing?

I need to use algorithm r.bioclimatic from GRASS in QGIS but I see that this algorithm don't exist in Processing Toolbox. A search a way of add this algorithm to Processing and in GRASS and Sextante ...
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3answers
77 views

GRASS convert raster to points

I have tried to convert a raster to points using this syntax: r.to.vect input=g_kelowna_merged@kelowna_mapset output=g_kelowna_points feature=point I have tried using the GRASS interface in QGIS and ...
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58 views

Why is QGIS 2.8.1 crashing when enabling Grass Plugin?

I am running Linux Mint 13 "Maya" (Ubuntu 12.04 Precise). I installed Grass via the software center. Than I installed Qgis 2.81 following this procedure: Add the lines for one of the repositories to ...
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25 views

Change GRASS module default parameter

I´m new to Qgis and GRASS. I need to change the default parameter skip of the module r.to.vect.lines, from its default value of 10 to 1.How can I do this? r.to.vect.lines [-v] input=name output=name ...
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18 views

Default horizonstep in r.sun

I am working on software suite to create some geoscience models on Digital Elevation Models. Part of the process is to calculate the Insolation Time and Global Irradiance using r.sun. We are running ...
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97 views

Simulate water runoff to get water height over each pixel of DEM

Here is my problem that I am trying to deal with. I have given a height map of around 512X512 resolution(It is Geo-referenced and I have the meta-data for this). And I have given that this area ...
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1answer
86 views

GRASS Zero-Crossing Edge Detection

I have a classification of vegetation communities across a landscape in a .tif format. I wanted to use the GRASS Zero-Crossing Edge Detection tool in QGIS to help define boundaries between my ...
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156 views

Can GRASS compute the line graph representation of an input graph?

I'm interested in computing a line graph for an input graph, preferably in GRASS since I'll be using other GRASS network analysis tools afterwards. I couldn't find any reference to line graphs in the ...
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119 views

How to create line segments between pairs of pixels in a raster?

I want to draw several lines between pixels (please see the image below) according to some criteria : First Criterion: The distance between 2 pixels is less than 2000m and greater than 500m ...
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16 views

Move Landsat 7 Image in Grass 7

I got 2 landsat 7 images from the same place but different date of adquisition, image A is well placed, but image B is shifted about 1500 meters east and 14700 meters north. I need to use both images ...
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22 views

Second order rectification display problems

I'm using GRASS 7.0 to geo-rectify oblique images taken from a fixed altitude and using RTK-GPS data as a GCP (as a vector file) for the process. The survey area is very small and flat, so I'm not ...
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2answers
38 views

How to combine the content of several mapsets into one new mapset in GRASS.?

I have some mapsets and i want to assemble them into one new mapset and have everything into it. How do i do it?
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2answers
770 views

Is it possible to use GRASS GIS in Python stand alone scripts?

I am trying to find a least cost path script for Python. I came across r.drain from GRASS GIS. Is it possible to use GRASS GIS in a Python stand alone script? If so where can I download the bindings?
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1answer
46 views

Grass r.out.gdal, wrong values when importing to QGis

I have a problem with export/import functionalities between Grass and QGis. I create a raster file in Grass (with r.wind.sun, but that most likely does not matter) It has the following properties: ...
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1answer
43 views

Duplicated vertices in contour features of GRASS?

I use GRASS to produce contours from DEM (r.contours for SRTM rasters). They looks fine, but most of the line features occures to be duplicated; i.e. verticies duplicated. Here are pictures of output ...
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599 views

Creating contours for specific elevations

Input data: 1. an SRTM raster. 2. Point file of peaks. -Attributes contain ID, x, y, z and the elevation at which the peak is completely isolated from a neighboring peak. The output I want is a ...
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63 views

How to process a big number of raster outputs with r.series?

I am new to python and QGIS. I'm trying to take some simple operations (e.g. count, average) over a big number of raster maps from a python script. I'm using the "r.series" algorithm (from processing) ...
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33 views

Calculating Odd and Even side of road using PyQGIS and GRASS

I'm trying to programmatically and automatically assign odd and even sides of a road to number homes using QGIS and GRASS. I noticed this other post, which gives a solution using PostGIS and I have ...
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103 views

Least cost path analysis : a lot of sources and destinations

I'm working on a 15*10 km area, splatted in a 50*50 m cell grid. I want to compute the time needed to travel from a single starting point to each cell centroid, combining driving and walking time. I ...
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1answer
63 views

GRASS make local relief error

While using/trying to make a local relief in GRASS with the plugin r.local.relief i stumble across a error. ERROR: G_realloc: unable to allocate 15000000 bytes of memory at ...
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103 views

Preprocessing GeoEye-1 in GRASS iatcorr

I am trying to do a study on land use change using three high-res images of an area from three sources (Quickbird, GeoEye-1, WV-3). I have managed to calibrate the Quickbird data using QGIS raster ...
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4answers
2k views

Rubber sheeting in GRASS or QGIS

We are in the process of getting our property boundaries corrected and a side effect of this is that we need to move any assets that have been drawn relative to the property boundaries, so they are ...
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1answer
618 views

Can't launch GRASS GIS 6.4.3 GUI on windows 8.1

As title, I downloaded GRASS GIS from this website: GRASS GIS - Home, and I choose winGRASS 6.4.3 standalone installer to download. After I installed, I click on its icon: I can't launch it even ...
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21 views

Why do GRASS' NC dataset and USGS' CONUS dataset coordinates disagree?

In the course of trying to figure out a specific data extraction task, I'm trying to understand the coordinate system used by GRASS. For a while, I'd been working with elevation data near Raleigh, NC, ...
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206 views

where to perform principal components analysis and tasseled cap transformation [closed]

I want to perform a principal components analysis (pca) and a tasseled cap transformation (tasscap) for a classification.Should i perform pca and tasscap on the original bands of my image or on the ...
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1answer
205 views

Export of group = multiband raster to another format not works in GRASS

I am really new in GRASS and my question is really basic but I dont realize where I am wrong. I have a set of single layers in my PERMANENT from some Landsat images (1 landsat = 7 one layer ...
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1answer
67 views

How to find the path after “cannot find module” message when I try to use grass tools in qgis [closed]

I use mac and when I try to use grass modules in qgis (brighton) I get a "cannot find module" message.
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1answer
200 views

How do I install mdenoise in GRASS?

How do I install mdenoise in GRASS 6.4.3? I've already successfully installed r.denoise, and have downloaded mdenoise from wget http://www.cs.cf.ac.uk/meshfiltering/index_files/Doc/mdsource.zip. How ...
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142 views

GRASS GIS : ScriptError : Unable to fetch interface description for command 'd.rast'

I'm new to GRASS GIS (6.4.3) and I'm trying to use the r.watershed command. I imported the GTOPO30 DEM in tiff format, but I can't display it. I get the following Script Error: "Unable to fetch ...
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4answers
9k views

How to smooth a DEM?

I have a SRTM DEM and I want to create a shaded relief from it. I created the shaded relief in GRASS and the result is very nice, but a little rough becouse the area is near flat and the DEM is 90m in ...
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85 views

How to merge two rasters when are on the same place

I have two rasters in GRASS GIS. first : raster of DMR, raster picture of relief - created from high values second : raster of buildings where pixels of every building have value of high of this ...
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53 views

I have an error when I execute a command in grass raplat

I use grass 6 in ubundu. I have putted the date into the .csv file and the antennas in .msi format, but when I try to execute the command in terminal "r.radcov" the system show me an error as: Error ...
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39 views

Grass functions (for example, r.li) on QGIS Processing Toolbox

I need to know if it is possible to add other functions, such as r.li to Processing Toolbox. Thanks.
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2answers
684 views

How do I reproject one raster to match another's in GRASS

I have two raster layers, A and B, which have information about the same location but have different projections and datums. How can I reproject layer A to match the projection and datum of layer B? ...