Questions tagged [saga]

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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2
votes
1answer
284 views

Why does SAGA raster calculator interpolate between cell values?

I have a raster layer with a series of integer values (classes) for each cell. I am trying to use the SAGA Raster Calculator module (called through QGIS) with conditional statements to reclassify each ...
4
votes
1answer
151 views

Why do I get this anomaly (vertical line) in my TWI raster?

I have derived TWI using SAGA GIS, Have a look on the center of the image, a vertical line goes through it from top to bottom. Anyone else confronted this issue?
7
votes
3answers
465 views

Using variable window (“kernel”) size for raster processing in QGIS?

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., "User-...
2
votes
0answers
157 views

Mosaic overlapping, irregular raster layers produces grid of NaN

I am trying to use the SAGA - Mosaic operator in QGIS 2.14.0 to mosaic two viewshed raster outputs I have. The viewsheds are irregularly shaped and overlap considerably, thus the need for the Mosaic ...
1
vote
0answers
210 views

Georeferenced Image Overlay and export to new image

I have two Geotiffs (one satellite image, one clipped image). I want to put the clipped image over the satellite image, because it shows flow velocity from this shown glacier (see image below). I ...
4
votes
1answer
322 views

Understanding SAGA Watershed Segmentation in QGIS: Error 1?

I am trying to run a watershed segmentation using the SAGA plugin in QGIS. Unfortunately, every time I have tried to run this on a specific file QGIS freezes. The log output reports the following: ...
3
votes
1answer
325 views

Catchment boundary polygon from catchment area raster

I am trying to generate a catchment area polygon from a digital elevation model. I am using SAGA tools in QGIS and used the Flow Accumulation (Flow Tracing) tool to generate a catchment area raster ...
2
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0answers
74 views

Does SAGA in QGIS processing can support no ascii name?

From Qgis, I am calling through Processing the Saga algs "clipgridwithpolygon" raster_inside_poly = processing.runalg("saga:clipgridwithpolygon", my_raster_temp, ...
2
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0answers
824 views

Importing TIFF to SAGA [closed]

I'm trying to import a large GeoTIFF (~1.2 GB) into SAGA GIS for processing as a grid using Import/Export - GDAL/OGR -> GDAL: Import Raster, but it keeps crashing. I'm using the 32bit OSGEO4W SAGA ...
1
vote
1answer
209 views

Solar radiation flux at 5 minute interval using GRASS GIS r.sun

I have been trying to estimate instantaneous total solar irradiance(w/m2) at five minute interval for a day (eg. 21 sept). I can do this in SAGA GIS by using "moment, mode 1" and running the solar ...
1
vote
1answer
217 views

How to delete by attribute from shapefile in SAGA command

I have lot of shapefiles to erase polygons with same attribute form them. It is usually an easy task when do manually, but how can I use SAGA-GIS command? Any help?
2
votes
1answer
1k views

Where does the output of a grid volume run in the Saga tool/ Qgis end up?

I have tried to do a grid volume run with the Saga grid calculus - grid volume function. After the run the window closes and nothing seems to happen, no message, no new layer or information appear. I ...
6
votes
1answer
755 views

Strange output from RSAGA topographic wetness index? [duplicate]

I am trying to generate a topographic wetness index raster with the RSAGA package in R. The output I am able to generate does not make sense to me, as it has a large number of NA cells and I wonder if ...
4
votes
1answer
2k views

SAGA tools in QGIS only allow save as .sdat file?

I'm just beginning to learn how to use SAGA 2.1.2 tools within QGIS 2.12.1 on a Windows 7 64 bit computer by working through exercises in Mastering QGIS by Menke et al. (https://www.packtpub.com/...
3
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0answers
161 views

Raster calculators in SAGA return incorrect results

Here's a sample of my dataset (one cell) with 28 different raster values, representing 28 individual Float32 rasters with identical parameters. 0.0000264434, 0.0049953502, 0.0007529828, 0....
5
votes
3answers
725 views

Dissolve overlapping polygons in SAGA

I've got the following (2D!) situation of overlapping polygons: I would like to have the polygon border dissolved such that I have only one polygon left. I thought this was a definitive case for the ...
10
votes
1answer
732 views

SAGA Inverse Distance Weighting in QGIS - How to Set Minimum Number of Points?

I am analyzing a postGIS point dataset in QGIS version 2.8.2, about 200k features total. To calculate weighted average values I am using the Inverse Distance Weighted interpolation technique. However, ...
41
votes
4answers
2k 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 ...
5
votes
2answers
2k views

Least cost path between various points QGIS

Is there an easy way to find the least cost path (LCP) between various points in an open source GIS? This question has actually already been asked here: How to find a least cost path through several ...
2
votes
1answer
164 views

Problem with Grid Statistics For Polygons

So honestly I have no idea what I'm doing, I'm a total beginner with GIS and I'm just following directions for an assignment given by my teacher. I am trying to use Grid Statistics For Polygons -...
3
votes
1answer
128 views

Check QGIS processing Saga version from a plugin

I am writing a QGIS plugin using SAGA by Processing. Is is possible to test whether SAGA is installed and which version is on? For GDAL, it's OK with: processing.tools.raster.gdal.__version__
3
votes
1answer
724 views

No Saga in QGIS 2.12

After installed QGIS 2.12 I don't have SAGA in Processing Toolbox anymore and I need it bad. Am I blind, can't find it or something went wrong? Any suggestions please? My OS is Win 7 64 bit.
2
votes
1answer
2k 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 ...
4
votes
0answers
252 views

SAGA Tool in QGIS Error: Load table: Proj.4-WKT Dictionary… failed

I have some problems with running SAGA tools in QGIS. I've downloaded and installed the software via the OSGeo4W Installer. It downloaded QGIS 2.12 and Saga 2.1.2. I wanted to use the Tool "Shapes To ...
2
votes
1answer
217 views

SAGA dissolve tool keep only one column of data

I have installed QGIS 2.12 Lyon and I need to dissolve multiple polygons according to one column in the dbf file (my layer is a shapefile). I have used SAGA "Polygon dissolve by attribute" algorithm ...
2
votes
1answer
2k views

Saga tools missing in QGIS [closed]

First things first! I am using Ubuntu Mate on 15.04. I installed Qgis and SAGA via the http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu packages. So I use QGIS 2.12 and SAGA 2.1.4. I ...
2
votes
1answer
97 views

Is it possible to inject a value into an algorithm text setting in QGIS Processing Model?

I have a SAGA Raster Calculator algorithm inside a model that I'm building. For the formula, I'm using the function (g1>20)*1 to give me a binary raster output. This categorises pixels to ...
3
votes
0answers
282 views

Improve tree extraction method

I want to extract trees from a given normalized Digital Surface Model (nDSM) in SAGA GIS. My workflow is the following: Applying a Gaussian Filter to the nDSM with search radius with standard ...
1
vote
0answers
56 views

How is “flat” defined in SAGA

SAGA has a feature that determines flats. Does anybody know how they define a flat? If I start with a raster, each pixel is flat - so it has to be more sophisticated than that. I would like to be ...
3
votes
0answers
272 views

Error when using SAGA's “topographic correction” algorithm in QGIS

I'm trying to do topographic correction of Landsat images using SAGA's "topographic correction" algorithm from QGIS' processing toolbox. I was able to do it using Minnaert Correction with slope and ...
2
votes
0answers
617 views

Delineate watershed using manual points in RSAGA

I'm currently trying for an automated solution to delineate watersheds within a large basin. I have a collection of locations (X,Y coords) for various tributaries reaching a larger river, and the end-...
2
votes
1answer
621 views

Trouble with kernel density estimation

I have been trying to find out how to make the SAGA and GRASS kernel density tools work in QGIS 2.8. I have had a lot of trouble trying to get them to work as they produce useless results seen below. ...
1
vote
1answer
98 views

osgeo4w not installing processing tools in QGIS toobox. [duplicate]

I have uninstalled and reinstalled QGIS several times from the OSGeo4W application. I have done this with no problem on several other times, but now I cannot get the tools to load. Most of the help ...
0
votes
0answers
509 views

Merge raster layers error

Is there an issue with the SAGA-tool "Mosaicking rasters"? I tried it with different rasters. In Sage itself it works fine. Algorithmus Mosaick raster layers startet... io_gdal 0 -TRANSFORM -...
1
vote
1answer
510 views

Merge layers (SAGA) ERROR

with QGIS 2.10 it is not possible to merge vector layers with the "Processing-Saga" tool (merge layers). The following error log comes up: Algorithmus Merge layers startet... shapes_tools "Merge ...
2
votes
1answer
173 views

Breaking closed line when intersecting with polygon using SAGA GIS?

I have a number of polygons (in lines shape) which represent the new condition of an area and a numder of polygons (in polygon shape) which represent the old condition of the same area. How can I ...
2
votes
2answers
605 views

How to sum values of overlapped pixels in thousands of rasters layers and clip it using a polygon in QGIS?

I have a lot of rasters files (more than 6000), each one represents the presence and absence of a species (1 for presence and NoData for absence). The set of rasters covers the whole Latin America ...
3
votes
0answers
962 views

how to orthogonalize building outlines

I'm looking for a way to orthogonalize building outlines which I've extracted from a high-res DEM. I'm using the FOSS GIS stack (QGIS, GRASS, SAGA, PostgrSQL, PostGIS) and can code in Python (or Java)....
0
votes
2answers
502 views

Does Processing plugin v2.10.1 not recognise SAGA?

Version 2.9.3 of the Processing plugin works fine, I can run the SAGA tools successfully. Updating the Processing plugin to version 2.10.1 results in SAGA disappearing entirely from the toolbox. The ...
5
votes
2answers
2k views

SAGA tool 'Relative Heights and Slope Positions' - What do results tell me?

I am currently trying to get in morphometry, using the SRTM 30m DEM. I was recommended to test the SAGA mudule 'Relative Heights and Slope Positions' (http://www.saga-gis.org/saga_module_doc/2.1.3/...
1
vote
0answers
326 views

QQIG/SAGA “merge shapes layers” algorithm removes underscores/pluses from layer names

I have a bunch of layers that are named layername_number+number that I want to merge. I need their names as source attribute so I used the "merge shapes layers" algorithm found under SAGA in the ...
4
votes
0answers
215 views

SAGA hydrological analysis in QGIS 2.8 on Mac

I am running QGIS 2.8 on a Mac machine and I want to calculate the catchment area using SAGA - Catchment Area. It starts running but after a while when QGIS wants to open the generated files there is ...
3
votes
3answers
2k views

Why is SAGA from the Processing Plugin not recognised?

Similar to SAGA algorithms don't work in QGIS 2.8 except that SAGA does not appear at all in the Processing Toolbox: As a check, I used the Python Console with the following code to see if any ...
1
vote
0answers
101 views

Hydrology Analysis via SAGA - what is the unit? [closed]

I did a couple of analysis via SAGA about an area in Iceland...I've never worked with SAGA before, could anyone tell me what Units the numbers in the legends for "Catchment Area Recursive" and "...
1
vote
0answers
109 views

GRASS and SAGA CentOS Linux release 7.1.1503 (Core)

I have a problem. I am developing a standalone app using QGIS but my script imports GRASS nad SAGA plugins and I have error to create the maps. I have CentOS Linux release 7.1.1503 (Core). SAGA is ...
2
votes
0answers
640 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 ...
2
votes
0answers
233 views

Merge vector layers problem with german names (ä, ü, ö…)

When I'm trying to merge (saga merge layers tool) some shape files I get an error log 'ascii' codec can't decode byte 0xfc in position 91: ordinal not in range(128) See log for more details Log:...
3
votes
1answer
1k 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 ...
0
votes
2answers
2k views

how to add multiple grids in SAGA gis

Here is the "big" problem: my Digital elevation model is divided in a lot of pieces (single files .xyz). In order to build a mosaic of them I need to import them all. With SAGA I can import them ...
7
votes
1answer
287 views

Why is SAGA kriging slower in QGIS than in SAGA itself?

I'm using QGIS for a while. In my opinion the SAGA kriging tool (processing toolbox) is very slow. Is that an QGIS issue? I tried to interpolate a point layer with 300.000 points (I know it is big) ...