SAGA (System for Automated Geoscientific Analyses) is a GIS toolbox with many modules that can be used from the GUI, command line or accessed through R,python or directly using C++.

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10
votes
2answers
746 views

Is it possible to manually correct a raster DEM (OpenSource)?

Is it possible, to correct a raster DEM by changeing the raster-cell-values manually, like by "painting"? My DEM (ASTER) have one small error where the elevation is about 300m below the actual ...
9
votes
2answers
1k views

How to implement viewshed calculation?

I'm looking for a way to implement visibility (aka viewshed). I found a previous GIS SE question that suggested a few GIS applications (not what I need - I'm trying to embed the calculations), and ...
8
votes
6answers
923 views

How to integrate SAGA Python Modules into ArcGIS Desktop?

I have been having a look at SAGA (http://www.saga-gis.org/en/index.html) and it seems to have some nice tools for geoprocessing. I was wondering if anyone out there has had any luck bringing SAGA ...
8
votes
1answer
306 views

Import GRASS and SAGA modules to python script

I'm new at this. I am "building" a python plugin for qgis and I want to import modules from GRASS and SAGA but I don't understand how to do it. The plugin I want to import is Kriging interpolation ...
8
votes
1answer
234 views

Where is this raster offset being introduced in the QGIS processing toolbox?

I'm using the (awesome!) processing toolbox in QGIS 2.0 to reclassify some NoData values in a raster from -9999 to 0, but at some point in the process there's an offset of about 0.2 degrees being ...
7
votes
3answers
4k views

How to calculate raster statistics for polygons?

how can I calculate sums, averages etc of raster-points (multi-band) per polygon of a vector-layer. I was told that this is called "zonal statistics". I tried that with QGIS first. There is a way to ...
6
votes
6answers
307 views

Tool/Algorithm for generalizing OSM-Files for printing maps

Is there a tool or algorithm to (topological) generalizes OSM-shapes? I would like to build a printable map in different scales. In the image below you can see the same divided road (yellow) at ...
6
votes
1answer
2k views

Calculate Topographic wetness index in SAGA

i am currently working on a project which involves the quantification of the wetness in certain areas. However it produces quite different results from what i expected. I'll describe the steps i have ...
6
votes
1answer
326 views

Generalize large polygon-file

I have a large polygone file with landuse information (6 classes). Its vectorised from a raster classification so the polygons are all angular. Any of my tries to generalize with v.generalize (sneaks, ...
5
votes
4answers
2k views

How to split a vector in equal smaller parts in QGIS or similar?

i want to divide a shapefile with many tiles into a lot of smaller tiles. I am searching for a smart solution, because manual edits are out of questions Anyone can help or know a nice function?
5
votes
2answers
313 views

Is there an open source alternative to ArcGIS for Desktop's Integrate tool?

I need to snap about 1000 lines in one layer to the lines in another layer (there are about 5000 lines in the second layer). The lines to be snapped are about 15 map units away from the base layer ...
5
votes
2answers
1k views

How to compare two DEMs and show their difference?

I want to compare my DEMs (ASTER GDEM2 and SRTM4.1). I know, that the GDEM has some extreme "holes" with totaly wrong elevations (I found 3 of them in my working area). Now I need to know, if there ...
5
votes
2answers
1k views

How to smooth large vector polygons from Raster

I have a landuse classification raster file (6 classes) of a large area. But I need it in vector polygons so I vectorised it. No problem so far, but the result is - of course - that every pixel is ...
5
votes
1answer
1k views

How to install SAGA 2.1 with QGIS dufour on Windows?

I need that someone tell me how i can install saga in qgis 2.0 correctly in windows, because if I install QGIS 2.0 and when I try to use SAGA I get this Missing dependency.This algorithm cannot be ...
5
votes
1answer
3k views

How to configure QGIS Sextante to use SAGA?

I have been trying to set up SAGA to work using Sextante in QGIS. I have followed the instructions to configure SAGA in Sextante, with the following input in the path for the SAGA folder C:\Program ...
5
votes
2answers
1k views

Efficiency of python script using SAGA and arcpy

=== SUMMARY === I have created a process to import a LAS point cloud, clip it, select the ground points and save the output as an XYZ.txt for clients to use. This uses a python based script (will ...
5
votes
1answer
97 views

Calculating Topographic Wetness Index (choosing from different algorithms)

Topographic Wetness Index can be expressed as Ln(a/tanB) based on the idea of Beven and Kirkby (1979) where a is the spesific catchment area (a=A/L, catchment area (A)divided by contour ...
4
votes
5answers
797 views

How to generalize and vectorize a LandUseClassification raster file?

I want to vectorize that rasterfile with its 6 landuse classes. The classification is very noisy and have to be generalized before. The result should be a polygone vector file. I use SAGA, (GRASS) ...
4
votes
1answer
236 views

Stripes in Landsat-image after topographic correction (SAGA)

I got stripes in my topographic corrected Landsat images (see second image below). I used SAGA GIS 2.0.8 at xubuntu 12.04 Image and DEM are in the same projection, tried it with EPSG:32636 and ...
4
votes
4answers
689 views

How to automatically plot intermediate contours with QGIS, GRASS GIS or SAGA GIS?

I'm mapping a steep mountain range. My main contour interval is 50 m and my intermediate contour interval is 10 m. In steep areas, the interval of 10 m is too small, so I need to leave ...
4
votes
2answers
152 views

How to de-noise a DSM

I have created a DEM, DSM, and nDSM from a LiDAR Point Cloud using SAGA-GIS. I extracted the appropriate returns from the point cloud, then converted to grid, and then closed gaps to fill in any ...
4
votes
2answers
596 views

Altitude Above channel in GRASS 6.4

i'm fairly new to the GIS world and GRASS (come from econometric background), i would like to do some species distribution modeling using R and GRASS. So i started to read the book of Tomislav Hengl ...
4
votes
1answer
1k views

How to perform Ordinary Kriging in SAGA via QGIS SEXTANTE Plug-in?

I'm trying to learn how to apply the kriging analysis in QGIS using the SEXTANTE plug-in and SAGA tools. It appears that I have my SEXTANTE and SAGA folders configured properly according to the user ...
4
votes
1answer
517 views

How to get SAGA working with QGIS Sextante?

I just created my account on this forum to find an answer to a stupid (?) problem I can't deal with. First, let's precise I just (some months ago) learned on my own what GIS was, and gave it a try ...
4
votes
1answer
203 views

How can I avoid reprojection gaps when merging DEM rasters?

I have two raster DEMs in same resolution I want to bring together. I was using the merge-function in SAGA, GRASS and QGIS but I always get the following result: What do I need? Where could the ...
3
votes
3answers
396 views

Topographic correction (for land use classification) with SAGA or GRASS

Is there a module in GRASS or SAGA (or a alternative open program) to do a topographic correction of a landsat image to enhance the land use classification? Thanks! Martin
3
votes
1answer
112 views

Debugging errors of SAGA interpolation algorithms in QGIS 2.0 Processing

I encounter recurrent problems with the geoalgorithms that perform interpolations. No matter technique I use I end with the following errors. As state in OGR tab QGIS is unable to open a file in C ...
3
votes
2answers
1k views

Installing qgis 2.0 and saga 2.1 on ubuntu 13.04

I have been trying to get this working for a few weeks now. I am trying to install QGIS Dufor (2.0.1) and Saga GIS from the Unstable branch of the UbuntuGIS PPA. When I attempt to do this I get the ...
3
votes
2answers
438 views

gdal doesn´t support my *xyz file

I have just exported a tif DEM to XYZ format with SAGA GIS. When I check this with gdalinfo it states that the format is unsupported? Seeing as I converted this with saga gis which used gdal I find ...
3
votes
1answer
3k views

Convert a shapefile with northing/easting to ASCII raster with latitude/longitude

Linked below is a polygon shapefile whose projection is NAD83 and whose values are LU/LC codes. Coordinates are meters of northing and easting. I would like to convert it to an ASCII raster with ...
3
votes
1answer
147 views

How to build a confusion matrix for image classification using SAGA or QGIS?

I did a supervised classification of a Landsat image subset using my training data polygons. I used SAGA GIS for that and everything worked out fine. Now I am stuck since I have no clue how to ...
3
votes
1answer
673 views

Hydrologic analysis with sextante-saga in qgis

(rough translation): Hi, I want to do hydrologic analysis of a DEM with sextante-saga in qgis. I found the plugin and the needed algorithms in SAGA, enabled them in the sextante toolbox, but when I ...
3
votes
2answers
278 views

SAGA-GIS:Viewshed creation from SHP instead of interactively?

I am using Saga-GIS to calculate a viewshed from a single point. I can do this with the interactive module, (terrain analysis > Lighting > visibility (single point) interactive) but how do I do it ...
3
votes
2answers
81 views

Merging DEMs of different grid size

I'm trying to merge two grids with different cell size. One has a cell size of 10m and the other 50m. The 10m one covers a subarea of the 50m one. I know that the most accurate one is the 10m one and ...
3
votes
1answer
93 views

Differences in raster extents in gdalinfo, SAGA & Quantum after resampling

I recently resampled a raster file using SAGA's Resampling module. The aim was to widen the extent of the new raster to two decimal places, where the original raster has three decimal places. The ...
3
votes
1answer
137 views

Convex Hull in SAGA Gis

How does one go about creating a convex hull from a set of points in SAGA GIS? I read that this is possible in QGIS, but I prefer SAGA and would like to see if it is possible. Furthermore, if it is ...
3
votes
0answers
97 views

How to configure QGIS and SAGA on Ubuntu (12.04 and others)?

During the past weeks, I have tried QGIS to recognize SAGA via the processing toolbox, both being installed from the ubuntugis-unstable repository. I have tried this on several virtual ubuntu ...
2
votes
2answers
125 views

How to set all pixels with value <= 0 to “nodata” in DEM raster?

I have a DEM raster with pixel values between about 3000 and -0.0003. I need to set all pixel with a value of 0 and smaler (<=0) to "nodata" (for later raster calculations and to reduce the ...
2
votes
3answers
646 views

Generate raster from isolines

I have a vector dataset of mean annual precipitation polylines, and I would like to generate a raster from them. I'm not sure the best way to go about it. ArcGIS has the Polyline to Raster tool but ...
2
votes
2answers
71 views

Enabling SAGA in QGIS

A similiar question has been asked recently, however I have some specific queries and process I have tried which are probably better in its own thread for clarity. Hope this is ok. See link to recent ...
2
votes
2answers
819 views

QGIS 2.0.1 Dufour on Windows 8 64-bit: Processing toolbox always produces error saying output layers could not be opened

I have tried to use the Processing Toolbox in QGIS 2.0.1 a couple of times now (using SAGA and OTB) and in both cases the processing tools always return an error along these lines: "Problem loading ...
2
votes
1answer
228 views

Kernel Density Error in QGIS Processing

I have been getting this error when trying to create kernel density maps using QGIS 2.0.1 and SAGA 2.1.0. It seems to occur only when the extent is large, i.e. the entire state of Texas. If I do it on ...
2
votes
2answers
47 views

Select polygons that do not intersect any other polygon using QGIS, GRASS, SAGA or R

I would like to select the polygons of the layer below that do not intersect with any other polygon (within the same layer). How can I do this using QGIS, GRASS, SAGA or R?
2
votes
1answer
123 views

Automating non-trivial workflow in SAGA-GIS

My problem: I have two DEMs, one rectangular and containing the other. Both are given in grid formats and the outer one has gridsize 50m, the inner one 10m. I want to 'embed' the smaller one in the ...
2
votes
1answer
101 views

What does the “Standard Distance” output from the spatial point pattern analysis in QGIS 2 represent?

I have a cluster of points and I am using the Spatial point pattern analysis tool from the processing toolbox in QGIS 2. I am having trouble understanding what the "Standard Distance" output is? It ...
2
votes
1answer
43 views

GRID TO TXT in saga

i have a problem in SAGA. I want to export several raster files to a .txt file. It means integration raster files to a .txt file. Can I do this in SAGA. Please explain? Thanks
2
votes
1answer
111 views

Creating New Modules in Saga GIS

I have recently started development with SAGA and have run into some difficulties. I have checked out the svn code base and have successfully compiled in VS-10 (except the project ViGrA). Now I just ...
2
votes
1answer
684 views

Installing SAGA GIS 2.1

I am using QGIS 1.9 master with Ubuntu 13.04. I tried to use the SAGA hydrology tools in sextante today and it said they did not appeared to be installed. I checked and sure enough SAGA was indeed ...
2
votes
1answer
114 views

How to open a .k format (I think it is made with IDRISI product) with open source software

I just received a .k file which I know it was made with a IDRISI software (i do not know which). I serched the web and I did not find many information on this format a part for a very essencial page ...
2
votes
1answer
548 views

How to fix erros loading result layers from SAGA functions in Sextante?

Using QGIS 1.8.0 and SAGA When trying to use the IDW function from Sextante SAGA 2.1.0 64bit, I get the following error: Could not load layer: C:/test.tif. This error seems mysterious to me, any ...