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
232 views

Calculate River Runoff Volume (Q) with GRASS

I want to calculate Hydropower between points at a River. I already created a Rivernetwork and the Accumulationmap (without weighting) with r.watershed. My next Step was to set equivalent points along ...
3
votes
2answers
302 views

GRASS GIS not starting

I have a problem with GRASS GIS 6.4.3. I installed QGIS 2.4 with GRASS GIS 6.4.3 GUI on Windows 7 64 bit - admin user. When I click on GRASS GIS icon the program not starting (without error messages)....
2
votes
1answer
602 views

QGIS 2.14 GRASS geoalgorithms don't work?

I instaled qgis 2.14 and grass geoalgorithms dont work. Only 160 geoalgorithms and should be 168. MsBox: Missing dependensy, It seems that GRASS is not correctly installed and configured in your ...
2
votes
1answer
80 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 ...
4
votes
1answer
79 views

Looking for similarity analysis tool between raster and vector layers in QGIS?

I'm aiming to do a similarity analysis between a raster layer and a vector layer. The raster layer is a 5-class ice map and the vector layer (points) contains ice jam events data. The goal here is to ...
3
votes
1answer
66 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, ...
4
votes
2answers
537 views

How to create a mosaic in QGIS with cutline and feathering for Landsat-8 imagery

1 - I have two scenes Landsat-8 RGB 6/5/4 and I need to mosaic them: 2- This is my cutline in polygon format that will smooth the overlapping area: 3 - So, I need to create a mosaic with ...
3
votes
1answer
74 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 ...
1
vote
0answers
47 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 ...
0
votes
2answers
302 views

Automatically apply topology rule to only selected portions of a .shp file?

I am looking for some examples/tutorials on how to apply a topology rule to only a selected portion of a shp file using a script in ArcGIS/GRASS. Using ArcGIS seems to always require an interactive ...
0
votes
1answer
61 views

installing grass71 on centos6

I am installing grass71 on centos6 , i have the following message after running grass71 [bachir@nexus ~]$ grass71 Starting GRASS GIS... g.gisenv: /lib64/libc.so.6: version `GLIBC_2.14' not found (...
1
vote
0answers
35 views

GRASS r.watershed problems in QGIS 2.12

I have a weird error when using r.watershed in QGIS and I have depleted all my ideas. Yesterday it was working normally and generating all the files, then suddenly it stopped working and shows the ...
15
votes
3answers
3k views

Is there a way to automate the preprocessing of LANDSAT data?

I'm currently enrolled in a remotesensing course, using LANDSAT data. Part of my course is about standardizing the scenes based on radiance values. I assume that because this is such a tedious task, ...
1
vote
1answer
34 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
60 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?
1
vote
0answers
41 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)...
0
votes
3answers
224 views

Looking for large GML files containing vector polygon data

I have few vector data files with 500 to 700 MB GML files. But I am looking for files larger than these preferably 1 GB, 2 GB. It would be helpful if somebody can provide some pointers regarding the ...
0
votes
1answer
64 views

Pygrass ERROR: Mapset is not set

I am using Pygrass in a a Python Grass GIS stand alone application. I am using GRASS GIS 7.0.3 on a Windows machine and Python 2.7.4. I am initializing a new Grass environment. I can work in this ...
3
votes
1answer
127 views

Why can't I enter decimals in QGIS r.water.outlet?

I am using the latest version of QGIS 2.14. I have a raster DEM file. I ran the r.watershed and it created all the raster layers for flow direction, stream, etc. My next step is to run r.water....
4
votes
2answers
60 views

Keep “no data” tiles with r.reclass rules

Working in QGIS 2.14.0-Wien. I want to reclassify a raster with the r.reclass GRASS 7 tool, but want to keep the "no data" tiles as "no data". I understand that I need to create a text "rules" file ...
0
votes
0answers
31 views

GRASS r.sim.water (ERROR: Required parameter <dx> not set)

Running r.sim.water (SIMWE) model: r.sim.water -t --overwrite elevation=elevation.10m@PERMANENT dx=elev2_dx@PERMANENT dy=elev2_dy@PERMANENT depth=depth160308_ niterations=90 output_step=1 fails ...
1
vote
1answer
23 views

v.overlay in GRASS

As I understand, v.overlay module can be used for polygons overlapping processes. Polygon clipping, union processes can be done. There are many algorithms for these operations. Which algorithm is ...
1
vote
0answers
42 views

v.net modules QGIS 2.14 OSX

the .net modules have been added to the toolbox for 2.14 but I can't see them running under OSX (10.11.1) using kyngchaos. I can see other Grass 7 tools but not the v.net ones. I know I can run these ...
8
votes
3answers
2k views

How to interpret GRASS v.kernel results?

GRASS manual reads: v.kernel - Generates a raster density map from vector points data using a moving 2D isotropic Gaussian kernel ... Ok, but how do I interpret the results? I understand that v....
1
vote
1answer
54 views

Specify target elevation with r.viewshed in QGIS processing toolbox?

How do I specify the target-height in r.viewshed when using the operator through QGIS's processing toolbox? It doesn't seem to be available. Who should I contact to adjust the interface such that the ...
2
votes
2answers
58 views

Create a new GRASS database in R with CRS projection

How to create a new GRASS database in R with CRS projection? I am able to create a new one using the following code but it is not projected require(raster) require(spgrass6) initGRASS("/Applications/...
0
votes
2answers
48 views

whats wrong with my exported raster reclassify map in grass?

I'm trying to export a reclassify map in grass to a Geotiff format to pass it to DinamicaEgo platform. I have 6 classes in grass but when I export it, the exported map show me 255 classes and they ...
0
votes
2answers
340 views

r.topidx error: required parameter output not set

I'm calling GRASS r.topidx from QGIS 2.2.0. I can get other tools to work on the DTM, for example r.watershed. But r.topidx I get the Oops message: Oooops! The following output layers could not be ...
1
vote
1answer
25 views

Set region with rounded values/coordinates

How do I set a region update with rounded coordinates. I usually set my region from a puffer around my points of interest and round up the north and east coordinates and round down the south and west ...
2
votes
1answer
47 views

Problems to use v.what.vect in GRASS7

I have problems to use the function v.what.vect and I'm not sure what is the issue. I have a simple forest polygon and try to determine if a point is in the forest or not. # check the output of the ...
1
vote
2answers
394 views

Error in r.terraflow

I used r.terraflow.short in GRASS, but it displayed this error: r.terraflow.short elevation=raster_bulacanElevation \ filled=raster_bulacanElevationFlooded1 \ ...
1
vote
1answer
62 views

QGIS: Grass Tools: Least cost path using r.drain generating flawed results

I am trying to use a combination of r.walk and r.drain in the QGIS grass plugin to model the most efficient path between two points, where cost is accumulated principally by movement over deeper water....
0
votes
1answer
192 views

Area of a Cross Section GRASS GIS 7

I have a task I would like to solve with GRASS GIS 7, if somehow possible. I want to create a cross section from a landslide - and would like to calculate the area of that cross section/profile. Any ...
1
vote
1answer
75 views

Calculating percentage of cells which are lower than site in Grass GIS?

In GRASS GIS: I have a shapefile with 300 hundred of sites (with height values for each point), and want to calculate the percentage or number of cells (of a given DEM) which are lower than the site'...
1
vote
1answer
53 views

cells w/in search window GRASS GIS

I am trying to find all cells that are a certain distance and within a certain window from a cell of interest. For example: I want all cells in a distance of 10m within a search window of 10 - 40 ...
3
votes
2answers
58 views

Making a simple line- complex

I am trying to make my own version of code to generate elevation profile for a line drawn over a DEM and I got stuck very early on. As a simple use case: I have a line that consists of just two ...
4
votes
0answers
81 views

Speed optimization of shadow computation with grass gis r.sun

I am trying to optimize the speed of r.sun to compute shadowed area on a DTM at 1m resolution. My current area is 3.39 km² but my final area will be 450 km². The r.sun wiki say that pre-computing ...
3
votes
1answer
139 views

Cannot open r.viewshed on Grass 7

I cannot open the r.viewshed tool in Grass 7.0.3. I am using the 64-bit version on Windows 7. The error message is given below: Traceback (most recent call last): File "C:\OSGEO4~1\apps\grass\...
3
votes
0answers
60 views

r.sun from QGIS toolbox doesn't give realistic value about the hours of insolation

I have a problem with the GRASS module r.sun when I run it in QGIS. I would calculate the hours of insolation in a specific site during a specific day. When I ran the algorithm "r.sun" from GRASS, it ...
1
vote
1answer
60 views

Sunshine hours duration calclulated from r.sun (GRASS Plug in) are same for diffrent date

Currently i am trying to calculate sunshine hours duration from r.sun (GRASS Plug in ) from QGIS 2.12. I want to calculate sunshine duration for 21 st jun and 21st December for same elevation data set....
2
votes
1answer
32 views

QGIS graphical modeler: how to automatically enter parameters in r.drain.coordinate tool

i am carrying out a cost least path analysis and i am using QGIS. The processing tools i am using are: r.cost.full and then r.drain.coordinate Considering i have more than 1000 layer to process (...
1
vote
2answers
117 views

GRASS init error in QGIS?

Every time when I start my QGIS I see the following message: GRASS init error: Problem in GRASS initialization, GRASS provider and plugin will not work : Module built against version $Revision: ...
2
votes
3answers
27 views

Grass 6.4.3 v.rast.stats: Calculate only one value

I am using the grass (6.4.3!) function v.rast.stats to calculate the mean value of rast values over polygons. The tool is somewhat slow and I actually only need the mean value. Is there any ...
5
votes
1answer
306 views

Grass NVIZ has no output in QGIS 2.8.1 ubuntu 14.04

I am trying to use the Grass7 NVIZ algorithm from the QGIS 2.8.1 toolbox, on ubuntu 14.04. I have enabled Grass7 in the QGIS processing preferences. I have compiled Grass7 from source, and Grass ...
1
vote
0answers
49 views

Python error when using r.reclass on raster with no CRS

I have a set of GRID data (directory of .adf files) that I'm trying to reclassify in QGIS. I'm using the GRASS r.reclass function to try to reclassify the layers, but GRASS keeps failing and ...
0
votes
0answers
9 views

Can grass 7.0.3 pansharpen Landsat 8 spectral bands [duplicate]

Can grass 7.0.3 now pansharpen Landsat 8 rgb spectral bands. The last post in 2013 said that a programmer was working on it.
4
votes
1answer
177 views

basin creation GRASS vs. flow direction

I have a strange behaviour in QGIS with GRASS tools. I am trying to create basins in the alp region and use he SRTM3 data. As I can see on the flow direction raster the SRTM3 data seems to act nice: ...
1
vote
0answers
22 views

QGIS and GRASS 7 integration [duplicate]

I want to integrate QGIS 2.12.3 or 2.13 with GRASS 7, but I still haven't been able to do so. Can someone please tell me how can I do this with a stable QGIS version.
0
votes
1answer
77 views

GRASS parser() error

I'm trying to use GRASS on python 2.7, but I'm having some problems at setting my script on IDLE, then I'm getting an error at parser() function: Here is my script: import os import sys gisbase = ...
1
vote
0answers
27 views

My OSM country roads network is not routable [duplicate]

I need a routable shapefile in order to execute pgrouting algorithms. I download a national zip from http://download.geofabrik.de/europe/greece-latest.shp.zip and import the roads shapefile in my ...