1
vote
1answer
40 views

Problem with batch mode Saga Raster Calculator

I have to do a couple of raster multiplications for which the batch mode would save me a lot of time. But the only thing I get are rasters that contain nothing but nan values. If I multiply the ...
1
vote
0answers
26 views

Easy way to extract raster cells OUTSIDE a vector (Mask) layer in QGIS?

I have a raster file but am only interested in the cells outside a certain polygon. This polygon is very iregular and scattered across the raster. Is there any easy way to extract only the cells ...
-1
votes
0answers
31 views

what is the math behind rasterization? Doubt [duplicate]

In Figure 4 you can see how the overlap is not complete (marked with circles). What I would like to know which algorithm that QGIS uses the rasterization? What is your standard? Is there a percentage ...
1
vote
3answers
154 views

What is the math behind rasterization?

I'm taking the first steps in QGIS (version 2.2 Valmiera) and I am having some difficulties in knowing what mathematical criterion that QGIS uses when converting polygons (shapefile) to raster. I'm ...
0
votes
0answers
33 views

Is the “1-band raster colour table” plugin available in QGis 2.0?

I used to use the "1-band raster colour table". Is it still available in QGIS 2.2.0? It seems like I can't install it (I don't find it in the list of plugins available, even after installing the BC ...
1
vote
1answer
46 views

How to read the count of the cells with data with non “no-data” values ,in QGis?

How to read the count of the cells with data with non "no-data" values ,in QGis
0
votes
0answers
18 views

Transformation type - when to use which type? [duplicate]

I am using QGIS 2.0.1 on a Mac, and I am georeferencing a scanned map from 1822. The image is an excellent quality scan, and includes a grid of lat-long. I do not know much else about the map that ...
1
vote
0answers
320 views

Cannot add the PostGIS raster layer with QGIS

I've imported some raster data in PostGIS database with the following command: raster2pgsql -s 31468 -I -C -M -t 50x50 /home/stefan/Quantum\ GIS/Neumarkt/NM_NW.tif public.demelevation | psql -U ...
0
votes
1answer
137 views

Installing raster resampling module in QGIS 1.8

On the website of Sourcepole, I have recently come across the case of resampling images in Quantum GIS. Because I am rather a beginner in GIS software I would like to ask you for information about how ...
2
votes
1answer
170 views

How to get mean of pixel values within a buffer zone around current mouse position in QGIS

for a qgis 1.8 python plugin I want to query the mean of all pixel values of a raster layer within a defined buffer around the current mouse position, not for an existing point layer. For the buffer ...
4
votes
4answers
400 views

How to display a “Save As” dialog for raster files?

I'm writing a QGIS plugin in python. I need to show a "Save as" dialog window in order to allow the user to select the path of the output raster file. Do I need to create a QFileDialog and manually ...
1
vote
0answers
122 views

Are there limitations with gdal virtual raster option?

I am new at Postgis and I'm groping... I pretend to rasterize some weighty vector layers in Postgis, do some map algebra and reclassification with them and visualize intermediate as well as final ...
5
votes
1answer
909 views

Save Visible WMS layer to file

Is there tool to save currently visible WMS layer to file in QGIS, or some place in QGIS where you can get needed xml to fetch it using gdal ?
1
vote
1answer
221 views

Qgis - Raster clip Problem

I tried to use the Raster (Extration) tool "clipper" and I always get this error log: What is my problem? Fehler bei der Ausf├╝hrung von Python-Code: Traceback (most recent call last): File ...
0
votes
2answers
855 views

Digitizing from OpenLayers Plugin in QGIS, or create raster?

Is there an easy method for digitizing from a layer added from the OpenLayers pluggin. As i cannot snap to it or use it as raster so the entire map does not load? two separate issues there.
3
votes
1answer
823 views

Get a pixel value

How can i do this operation: I want to get a pixel value fro the satellite image (Landat, GeoTIFF, 7 bands) using qgis-python. What operators should i use? (for example in qgis's Python Console) ...