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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12
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4answers
16k views

Splitting shapefile into separate shapefiles for each feature using QGIS/GDAL/SAGA?

I have a polyline shapefile with about 20 kinds of roads. I would like to know how can I create automatically a vector file for each one. I am aware of how to do it using ArcGIS for Desktop - see ...
8
votes
4answers
6k 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
1answer
3k views

Performing 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 ...
9
votes
5answers
12k 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 ...
4
votes
1answer
370 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 ...
5
votes
3answers
712 views

LiDAR data density, returns per square meter

How can I compute a raster showing the number of return points per square meter using SAGA GIS or other open source software? My goal is to obtain a mask which would show me the places (cells) ...
6
votes
2answers
765 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 ...
5
votes
1answer
7k 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 ...
8
votes
2answers
586 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 ...
2
votes
1answer
875 views

Getting Negative Topographic Wetness Index (TWI) values in SAGA GIS?

I am getting negative topographic index wetness values in SAGA GIS - anyone else every get this? Not all negative values, but the minimum of the TWI range is negative for some steep watersheds we are ...
5
votes
2answers
3k 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 ...
4
votes
2answers
774 views

What is the source of horizontal and vertical striping in USGS DEMs?

When processing 30m and 10m DEM data downloaded through the National Map Viewer from the National Elevation Dataset, we noticed horizontal and vertical striping not only in the produced results, but ...
2
votes
0answers
365 views

Problem loading output layer QGIS

Every time I run operations with temporary file output from the graphical modeler, I get the following error message: Oooops! The following output layers could not be open CLIP: ...
32
votes
4answers
711 views

Generating equal sized polygons along line with PyQGIS?

I would like to create polygons along a line to use them for AtlasCreator in a next step. ArcMap has a tool called Strip Map Index Features. With this tool I can choose the height and width of my ...
8
votes
5answers
6k 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 ...
12
votes
2answers
2k 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 ...
3
votes
3answers
923 views

How to calculate peaks in a DEM

How could I extract all peaks from a DEM (large mountainous area)? Peak means something like: a pixel which is sourrounded by other pixels with smaler elevation numbers in a area arround the ...
1
vote
1answer
850 views

How to make GRASS and SAGA tools capable to use in QGIS?

I installed QGIS, GRASS and GDAL by OSGeo4w package, and as I finish the installation, I want to use GRASS tool, I face this problem: But I already installed GRASS and SAGA, how to make those tools ...
10
votes
2answers
3k 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 ...
8
votes
4answers
1k 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
1answer
353 views

How to calculate “water accumulated in each cell” using QGis?

I create channel network and catchment area from a DEM with SAGA GIS. I know that flow is starting from a cell to an other cell. Firstly, a cell is filled with water and then it is starting to flow ...
8
votes
1answer
450 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
2answers
4k 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 ...
6
votes
1answer
4k 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 ...
5
votes
1answer
4k 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 ...
3
votes
2answers
1k views

Exporting 16 bit single-band to 8 bit in SAGA/QGIS

Everytime with every function (e.g convert data storage type or gdal-translat -ot Byte) the output is a completely white map with a black border. only the "save as" export works, but the TIFF also ...
3
votes
1answer
4k 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 ...
2
votes
2answers
719 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 ...
1
vote
2answers
1k views

Interpolation of contours (from one “main-contour-shapefile”)

I calculated, that the best and smalest possible äquidistance (equidistant) for my map is 30m. After I generlized my DHM, I extracted contours of a intervall of 30m and smoothed them. Now I have my ...
6
votes
3answers
106 views

Variable window (“kernel”) size for raster processing

I'd like to use differently sized windows as I process (a.k.a. filter) a raster, with the size varying according to latitude. There are tools that allow a user to specify custom windows (e.g., ...
4
votes
1answer
279 views

What are definitions of watershed segmentation, local maxima, variable window search, regarding LiDAR for vegetation?

I am not familiar about Lidar. I want to measure trees height and number of trees. I guess, watershed = to locate the trees, local maxima = to measure trees height. I used these methods in SAGA GIS. ...
3
votes
0answers
296 views

SAGA is not working within sextante (QGIS processing installed in Ubuntu)

Recently i decided to start working in Ubuntu (version 14.04). My first step was to add the ubuntugis-unestable repository, and then proceed to install SAGA, GRASS, OTB, QGIS and the bindings between ...
2
votes
1answer
580 views

QGIS 2.12 & Ubuntu 14.04 SAGA installation not found

Installing QGIS 2.12 on Ubuntu 14.04 from the debian trusty ppa. Upon opening QGIS I notice the following error under the Processing tab: Problem with SAGA installation: SAGA was not found or is not ...
2
votes
1answer
365 views

(R)SAGA: saga_cmd 2.1.0 error? inconsistency?

frequently I am using (R)SAGA, but after SAGA became >2.1.0 the R package is no longer working. The last update for RSAGA was 07/2013. Thus I downgraded SAGA to 2.1.0 (first try was skipping the ppa ...
2
votes
1answer
392 views

Sextante in Qgis 1.9 alpha on Ubuntu can't find saga gis 2.1

I am using Qgis 1.9 on Ubuntu 13.04, Sextante is a core part of qgis now. I am trying to access the SAGA 2.1 libraries through qgis and I keep getting a popup window that says SAGA is not installed. I ...
2
votes
3answers
2k views

Generating raster from isolines using SAGA or ArcGIS?

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 ...
1
vote
0answers
80 views

Why does the “local maxima” module in SAGA GIS put so many “maxima” points on lakes and plains?

SAGA GIS puts too many maxima points on plains and lakes. Why does it happen? Is there a way to avoid this? It's not really a big problem (the value is correct) except for the size of the SHP files in ...
1
vote
1answer
493 views

SAGA algorithms don't work in QGIS 2.8

when I have installed recently QGIS 2.8 and, since then, SAGA algorithms don't work. Apparently, the algorithm runs well (any error is showed while it is executing the algorithm), however, there is ...
1
vote
0answers
73 views

Is there a list of Open Source tool alternatives for ArcGIS tools? [duplicate]

Is there any place one can find a list of ArcGIS alternative or near-alternative tools found in (any of) the open source softwares? I am not looking for software but individual tools found in the ...
1
vote
1answer
333 views

setting SAGA folder for QGIS with OS X macports install

I am trying to get the toolbox to work in QGIS 2.6, but I keep getting an error message that SAGA is not properly configured. After much digging, I finally found I can set the SAGA folder in ...
1
vote
0answers
517 views

QGIS SAGA Channel network error: Input layers do not have the same grid extent

I am trying to follow along with this exercise using my own DEM. I have done the first step, creating the catchment area, with no trouble. When I try to run the Channel network algorithm, however, I ...
0
votes
1answer
137 views

Fill polygons via data-defined pie charts

I am trying to summarize my polygons by each's distribution of some variable. To couch the discussion, let's say we wanted to summarize the demographics of each county (of a small state) by it's ...