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.

learn more… | top users | synonyms

1
vote
1answer
29 views

Neighborhood analyses with GRASS/QGIS using ASTER GDEM

I have a problem related with this question (Old question without answer: R.Neighbors with large neighborhoods?). Basically, I want to estimate roughness of a given area, for which I was using QGIS, ...
0
votes
1answer
28 views

r.patch results in a blank map in GRASS

I have a collection of tiles downloaded from the EDINA Digimap service, in asc format. I imported these into GRASS using the r.in.gdal function, and they appear in the display screen as expected. I ...
1
vote
1answer
48 views

How to merge adjacent polygons with no common attributes in GRASS?

Many topics are talking about merging polygons based on their common attributes, but few (or none) give a real answer to location-based merging problem. Explanation. Here is a fraction of the base ...
2
votes
1answer
38 views

QGIS - best fit to the sectoral terrain (SRTM 30m resolution data)

i need a help to find out the Slope of "best fit to the sectoral terrain". here is in details about the area of calculation. we have a reference point, from the reference point our sectoral area ...
1
vote
1answer
53 views

Question about Using r.mapcalculator in Python console

According to the following conversation: Using r.mapcalculator in Python console? I tried: ##NoData Background=name ##RASTERLAYER_BAND=raster ##nodatabackground=output raster import processing ext ...
1
vote
0answers
39 views

GRASS gis: treating certain cells as starting points in mapcalc

I am attempting to calculate the vertical height from horizontal of every point on a slope. I want to use stream beds (the lowest points in my DEM) as my starting spot, with the horizontal plane ...
0
votes
0answers
36 views

n-dimensional visualization software

I am using Grass 7.04 standalone. I have made a 3d view of dem raster. How can I have a high resolution image file of it to work with photoshop? It seems that the only tool to have it is Nviz but it ...
3
votes
1answer
86 views

GRASS r.reclass QGIS 2.14. error: “the following layers were not correctly generated”

I am getting a strange error message when running the GRASS r.reclass algorithm. The error states that: "The following layers were not correctly generated *reclassified You can check the ...
0
votes
0answers
7 views

plotting a proportional sized snowfall fall pin ( also the numerical number) for 150 kal local ng positions on a us map

just starting to learn Grass. Need to learn how to have a usa outline map. (Is this spearfish?) On the map place pins ( for a given latitude and longitude) proportional in height for annual ...
5
votes
3answers
163 views

Smoothing method for big polygons

I'm looking for an alternative to 'snakes method' for smoothing very big polygons, which I created from SRTM elevation datasets. The problem is that the smoothing is getting stuck after a while with ...
0
votes
0answers
24 views

Problem with i.landsat.acca on GRASS

I have a problem with my Landsat Tree Cover Continuous Field. The images are fully of clouds and shadows, so unreadable. The problem is the following: when I try to use i.landsat.acca to remove ...
1
vote
2answers
64 views

Error installing addons in GRASS 7.0.2: File is not a zip file?

When I attempt to install an addon in GRASS Setting->Install Extension from Addons and select the addon i want from the list (r.stream.order) i get the following error: "ERROR: File is not a zip file: ...
0
votes
1answer
28 views

How to calculate stream order in GRASS 7.0.2?

I would like to calculate Strahler's and other stream hierarchy from my input raster but I am not sure how. This manual suggests tat I should use r.stream.order command, however in version 7.0.2 "...
1
vote
1answer
84 views

Positive Topographic Openness - do any FOSS tools (other than SAGA) provide this?

I'm looking for a FOSS GIS tool to provide Positive Topographic Openness on 32-bit Ubuntu. (which rules out ArcGIS) Normally I use SAGA GIS for this, but my Ubuntu setup is a bit messed-up after a ...
0
votes
1answer
21 views

R.patch creating enormous file size

I'm using r.patch (within QGIS, GRASS 7) to patch two Float32 rasters both of which have a respective filesize of under 200MB. When I save the memory layer raster created by the r.patch function, the ...
0
votes
0answers
15 views

Grass Gis i.atcorr for Aerial data

Can Grass GIS i.atcorr module be customized for Aerial sensor? Attempted for Aerial sensor which has altitude of 13km. but module is failed .if the satellite altitude is changed to 100 km, module is ...
1
vote
0answers
27 views

Raster Precision QGIS

I am using r.patch extension in QGIS to join a number of LiDAR tiles, some of which overlap hence i am carrying out this task before utilising in a hydraulic model. R.Patch works fine, however the ...
1
vote
1answer
28 views

How to open .jp2 with GRASS 7.0.3

Does anyone know if I can use Grass to open a .jp2 image file? I am aiming to do some image classification on the image and when I try to import the image into the program a stream of errors comes up ...
1
vote
0answers
44 views

OS X Yosemite: copy / paste into shell GRASS 6.4.4. within QGIS 2.14.0

I want to know How to copy/paste into GRASS 6.4.4. shell within QGIS 2.14.0. I'm working with OS X Yosemite and the right mouse button doesn't work neither shortcut (cmd+c/cmd+v)
1
vote
2answers
35 views

How to export vector file in GrassGIS to QGIS

I am using GrassGIS to analyze watershed. I created a stream vector extracted from raster elevation data, how to extract the stream vector file so I can open it using QGIS?
2
votes
0answers
28 views

How do I merge a point attribute table to a polygon attribute table in QGIS or GRASS?

I have a point layer containing the following data: I want the following polygon areas to be added to the point attribute table as all the points occur inside the various features of the polygon ...
1
vote
1answer
67 views

How to design a flood with water elevation on a specific point?

Actually I have to know the flooding area caused by a rise of the water level due to the implementation of a dam. So I would like to know if there is an extension or any tool in QGIS or GRASS which ...
4
votes
1answer
338 views

Cannot locate GRASS plugin in QGIS 2.14.1 on Linux

I am trying to load the GRASS plugin in QGIS but it is not shown in the plugin manager (no matter if I turn on experimental and deprecated plugins). Under processing / options / providers GRASS GIS 7 ...
1
vote
1answer
17 views

Grass GIS animation tool: zoom in to area of interest

The Grass GIS animation tool is great, but I'm struggling to be able to zoom into an area of the original rasters. Do I have to clip the rasters to achieve this, or can I use the advanced section of ...
2
votes
1answer
147 views

Cost Distance Map in QGIS

My question is very similar to Cost Distance Analyst In QGIS? However, I'm looking for a means by which I can create a raster displaying the cumulative cost of each pixel to a specified destination ...
1
vote
1answer
23 views

Matching Python and GRASS projection

I have a colleague producing maps with the following Python Basemap projection: from mpl_toolkits.basemap import Basemap m = Basemap(width=6000000,height=3900000, resolution='l',projection='...
1
vote
2answers
31 views

Issue running r.region in GRASS command line

I'm currently attempting to use r.region to preform analysis on a specific area of a raster image. I'm receiving Lat/Long data from the step before me, but I'm having issues use that data in r.region....
1
vote
1answer
22 views

To display custom data on a Shape file

I have a shape file which is a district map. There are close to 800 districts. There are around 30 funding agencies. There are 4 different health programs. The different funding agencies fund specific ...
3
votes
1answer
37 views

Is it possible to start the GRASS GUI from R?

I am using the rgrass7 package in R in order to work with GRASS GIS. After having set the needed enviornment variables, I can now launch a GRASS session from R and and work on my GRASS data using ...
1
vote
0answers
17 views

GRASS 7.0.3 - Script to automate multiple simulations?

I am working in GRASS 7.0.3 and want to conduct a complex analysis of Least-Cost Paths of the many-to-many type. Specifically, I do have my elevation raster (ASTER DEM) and point data of 300 random ...
0
votes
0answers
30 views

Problems with QGIS 2.14.1 and GRASS 7.0.3 [duplicate]

I been having problems with modules GRASS / GRASS 7.0.3 in QGIS 2.14.1 I did the installation with Standalone Installer QGIS Version 2.14 (64bit) QGIS-OSGeo4W-2.14.1-1-Setup-x86_64.exe My OS: ...
2
votes
0answers
100 views

Grass processing not configured in OSGEO4w QGIS 2.14.1

I get the below error when I try to use grass processing from within QGIS. The error is given on all commands and I have got this error on 2 machines. I am using windows. "This algorithm cannot ...
2
votes
2answers
268 views

QGIS 2.14.1 Processing Toolbox GRASS 7 .NVIZ Not working

I have a problem with the command GRASS 7 .nviz in QGIS 2.14.1 installed through QGIS-OSGeo4W-2.14.1-1-Setup-x86_64.exe.md5sum all GRASS commands work exept .nviz / nviz7 images: I test with ...
0
votes
0answers
22 views

Process road polylines to not overlap building polygons

Is anyone aware of a processing tool in Grass or similar which will find segments of polylines which overlap polygons in another dataset and reroute the polyline to avoid the collision? My problem is ...
3
votes
1answer
78 views

Convert xyz points to topography and calculate mean slope

I am working on point data (x, y, z) in meters from origin. I have between 24 and 35 points for each plot (10mx10m), with random locations. I would like to modelise topography over the whole plot in ...
2
votes
1answer
63 views

command r.stream.order not found in grass 7.0.3 how to install r.stream module?

I have installed QGIS 2.14.1 and GrassGIS 7.0.3 I found in OSGEO Grass wiki page a command that calculate Strahler's and Horton's stream order Hack's main streams and Shreeve's stream magnitude from ...
1
vote
2answers
27 views

What does the max_slope_length option do in GRASS r.watershed?

What does the max_slope_length option do to the r.watershed program in grass? According to the manual, it should limit the length of a stream. Does this mean a max_slope_length equal to the raster ...
3
votes
0answers
14 views

What does the blocking option do in GRASS r.watershed?

What does the blocking option do to the r.watershed program in grass? According to the manual, it should stop water from being routed past that location, but it appears to have no effect. I'm trying ...
5
votes
2answers
123 views

GRASS r.in.lidar tool generates incomplete rasters

I have been trying to import a huge LIDAR file (10.5) Gb to GRASS GIS using r.in.lidar. It does the task, but only for part of the image, as shown below: Canopy Height Model (CHM) generated with ...
2
votes
2answers
183 views

Where is the nviz tool in qgis 2.14 with GRASS 7.0.3?

I hope Im not blind but I looked in the grass tools (modules) and qgis plugins but couldnt find it. When i try to run nviz from GRASS the whole programme chrashes just before concluding. Its a ...
3
votes
1answer
76 views

How to use GRASS raster tools in the Processing modeler?

In the Graphical Modeler of QGIS, I don't see a way to import a layer into GRASS. The modules "import loaded raster" are not accessible in the Modeler. I want to use GRASS reclassify module, because ...
2
votes
1answer
90 views

Quantile in QGIS python Plugin

QGIS is very powerful when it comes to styling Vector Data. When it comes to Raster data, ArcGIS still has some advantages including Styling based on Quantiles. See my earlier post: For this I want ...
3
votes
1answer
72 views

Invalid Geometry, what's wrong with the geometry?

I am using QGIS (2.10) to make a growing zone map of the U.S. from some data I found online. I need to reshape to fit into a U.S. map, and I find it's easier if I break the shape into smaller parts, ...
1
vote
0answers
51 views

Calculate shortest paths for each output area in catchment through road network to a single point (i.e. store)

The title sums it up pretty much. I'm looking to derive trip distributions to a single store using population data and distance within a prescribed distance catchment. I have calculated the catchment ...
3
votes
1answer
79 views

Understanding intersection of GDAL and QGIS?

Background I'm starting a project that will be done entirely through Python, except perhaps at the end for visualisation. So far I've been doing it with ArcGIS and arcpy, but we'd like to move it to ...
8
votes
3answers
172 views

Why are the holes in my polygons not generalized?

I have one polygon layer with many holes. I would like to generalize it. I used v.generalize of grass. With it, I used chaiken algorithm. But, only the borders of polygons were generalized, the holes ...
1
vote
1answer
35 views

Pygrass reading raster issue

I'm tring to read a raster map from my grassData. I'm using this code import os import grass.script.setup as gsetup from grass.pygrass import raster gisbase = os.environ['GISBASE'] gisdbase = os....
4
votes
1answer
61 views

Reshape polygon to boundary of other polygon

I have two polygons. The first one has a white background and brown boundary. To othr has the pink background. how is it possible to reshape to first polygon to the boundary of the other polygon?
2
votes
1answer
260 views

How to set QGIS 2.14 on OS X to use GRASS 7

My current QGIS installation (2.14) on OS X 10.11 is set up to work with GRASS 6.4.4. I am guessing this is the default GRASS version that comes preinstalled with the QGIS package maintained by ...
1
vote
0answers
46 views

Will Grass GIS 6s atmospheric correction take raster as input for atmospheric parameters

I am working on atmospheric correction using 6s in Grass 6.4.4 version(i.atcorr module). I want to use raster data set for atmospheric parameters. Presently I am creating an icnd (input condition)...