0
votes
0answers
19 views

How to avoid random transparent pixels in georeferenced grayscale raster images?

I'm in the process of georeferencing some old black and white aerial pictures from 1990 in QGIS 2.4. So far, this is business as usual, no problems. Of course I get the usual black triangles, because ...
1
vote
2answers
40 views

qgis raster style 'no data value' checkbox is ignored - what's a good workaround?

See bug report filed here: http://hub.qgis.org/issues/10236 Note the initial bug report got 'fixed' but that fix introduced this new error, so the issue was reopened a few days ago. Anyway, it ...
0
votes
0answers
29 views

Disable option in QGIS which picks 4th band as alpha band

Is there a way to disable that function? As somebody who works with 4 band orthoimagery on a daily basis, it is annoying to go to the transparency options every time I load an image to disable the ...
1
vote
0answers
27 views

Set Default Transparent Pixels in QGIS?

Is there a way to set QGIS to automatically load in images with no data values of (0,0,0) as transparent instead of black? I've looked through the forums, tried saving a .qml file out, looked through ...
2
votes
1answer
71 views

How to set the transparency for multiple layers or add a global transparancy preference?

How can I set the transparency to 27 % for all 245 layers in QGIS? The only way I know of is by right clicking on the layer name, selecting Properties, then Transparency and then moving the ...
2
votes
1answer
130 views

How to change layer transparency without changing border lines?

I have a raster image of elevations. I have added a vector shapefile that contains local political divisions. I want to keep the elevation colors, but I want to keep the black lines representing the ...
2
votes
1answer
151 views

Change Values of Georeferenced Raster

I am using QGIS to georeference B&W images. I have now done this and would like to set the black surround of the image (as a result of the georeferencing) to transparent but this does not work as ...
2
votes
0answers
192 views

How to render a transparent raster layer on top of one or more vector layers with PyQgis?

I been trying to render a map with a 3 vector layers and one raster layer. The idea is that the raster layer should be on top of the other 3 vector layers. The problem is that even when I add the ...
0
votes
0answers
70 views

QGIS: “No data” raster value for missing rows conflicts with data?

I’m having a problem with specifying “no data” in a raster dataset in QGIS 1.8.0-Lisboa. QGIS does fine in interpreting pixels I don’t have rows for as “no data” if I set Layer Properties -> ...
1
vote
2answers
89 views

How do I adjust transparency on heatmap so that I can see background raster map? QGIS 1.8.0

I have created a raster heatmap for the first time, but I cant seem to adjust the transparency settings to let me see another background OS raster map beneath it. I have attempted to swap the ...
6
votes
3answers
2k views

How to make transparent the background of a topographic map in QGis 1.8.0?

I'm starting to use QGis 1.8.0. I have a raster topographic map, i.e. white background and black contour lines, houses, roads and so on. I want to make transparent the white background, so if I ...
1
vote
1answer
183 views

Why is transparancy of GRASS rasters missing when imported into QGIS?

I have a raster map in QGIS imported from a GRASS mapset with the QGIS GRASS plugin. The problem is that I have null() cells in the GRASS map that appear "colored" in QGIS. How can I set the ...
1
vote
2answers
1k views

QGis problem with raster transparent

I am new to QGIS. I found the problem impossible to solve the parts of raster data that are in TIFF format should be made transparent. What do I do?