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I made a map in QGIS.

Now I want to export the resulting image (layers upon layers) for further processing in GDAL.

The print composer only lets me export an image up to a fixed size. If I try to make it bigger via resolution or paper size, it says there might be a memory leak and refuses to export.

How can I export my map at a very high resolution (think 100k pixels per side)? I know it sounds silly but I really want to do this.

By making a map I mean adding various layers (vector and raster) and styling them. By map I meant the map view or a map view in the composer.

There totally might be a memory leak, I would think the developers removed the error otherwise (it is a non-quitting QGIS message dialog). I have lots of swap space though, so even if, it should be able to go very slowly.

I fully expect this to go above 10 gigabytes as GeoTIFF, that's totally fine for me. One of my inputs is 25G and ideally I would use it at 1:1 scale in my export. I did try the commandline export but QGIS simply quit (or crashed, gotta re-check) without outputting an image.

What I really want to do is create TMS tiles in a specific non-webmercator projection (EPSG:3035). There seems to be no sane workflow for this, so doing it via tif export, then gdal2tiles seems the best way. QTiles does not support anything non-webmercator.

underdark
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bugmenot123
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    Can you please elaborate on what you mean by "made a map in QGIS" (What is it composed of, workflow etc.), what resolution is the input and why exactly you want to do this (especially the "further processing in GDAL" part). – Kersten Jul 06 '15 at 14:43
  • If it says that there might be a memory leak, maybe it really is. Maybe you can move your project to a more powerful computer and try there? – nadya Jul 06 '15 at 15:47
  • You're talking about generating an image that could be in the gigabyte range for file size. Content matters so file size varies with format and content, but a gigapixel image at 41k x 27k pixels weighs in at 2GB and you're wanting something 4-6 times that size. I did note a related question here: http://gis.stackexchange.com/questions/3718/ Another option would be tiling - break your image down into sections and then stitch them all together after output. – Chris W Jul 06 '15 at 19:12

1 Answers1

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Make sure you're using a 64 bit build of QGIS. The limitation on exported composer sizes/DPI is much higher on a 64 bit build.

ndawson
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  • I do! Any idea what the exact limitation is? Does it check for available RAM and decide on that? Maybe I should disable the check for testing. – bugmenot123 Jul 07 '15 at 09:08
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    @bugmenot123 - The maximum limit in terms of Export Resolution for me (QGIS 2.8.2, 64-bit on Windows 7) is 3000 dpi. – Joseph Jul 07 '15 at 09:52