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I have problems using the function TIN(linear) interpolation in Qgis. The program crashes when larger areas is interpolated.

Map properties: vector map, Geometry typ = Point, features in this layer: 523851, EPSG:32633 - WGS 84 / UTM zone 33N, files = .shp

When i divide the map into more layer(like 80 000 points each) and then interpolate them together(by adding more layers in the interpolation meny), it works, except some areas still makes the program crash.

Any idea how to solve this? Or have someone had/have the same problem?

Maybe the problem is: can´t handle large files or the algorithm have problems triangulate between some points patterns.

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Some clue how to do TIN interpolation using different program? –  Bersan Nov 12 '12 at 11:48
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What is the resolution you are trying to obtain? –  WolfOdrade Feb 7 '13 at 18:31
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What is your OS? –  Brad Nesom Feb 8 '13 at 2:36
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4 Answers 4

I have found personally that QGIS will crash when it runs out of memory. This happens when you're printing some big, raster heavy maps. So I reckon that's what is happening here.

You could try some alternative methods. Some suggestions I have are:

  1. Use GDAL http://www.gdal.org/gdal_grid.html
  2. Try using GRASS via the QGIS plugin
  3. Get down and dirty with Python! This looks good: http://hpgl.aoizora.org/index.php?option=com_content&view=article&id=47&Itemid=56 or this: http://docs.scipy.org/doc/scipy/reference/tutorial/interpolate.html
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Since it may have to do with memory.
You might try.

  1. Clear trash bin.
  2. Clear windows temp. Assuming windows.
  3. Set virtual memory (or RAM disk on other OS) on a second drive.
  4. Make the RAM disk manually managed and set the min max to the same value.
  5. If you have 12Gb free use that. If the drive is empty when you set it up the RAM disk will be contiguous which will help with performance.

Another note: lots of work but I have seen some threads about problems arising from differing projections.
You could reproject all data sources to one PCS.

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I think I have lots of memory on my computer, but realizing that it is a memory issue (most of the rest of it I did not understand) led me to simplify the geometry of the contour lines (Vector > Geometry Tools) to vastly reduce the number of nodes without seeming to lose much accuracy. The raster interpolation plugin worked fine once the number of nodes was down enough. Thanks for the direction!

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QGIS will have memory issues and I think you want open source solution.

For TIN operations, I always use Triangle which you can download at: http://www.cs.cmu.edu/~quake/triangle.html

Simple and easy to use.

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