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I have a group of classified raster files, showing point densities at 3 intervals. I want to create contour lines based on this data at these same intervals. I'm guessing this should be fairly easy, but how? I'm on ArcGIS 10.1.

EDIT: I have about 100 raster files, each of them is a group of points which I've performed a Kernel Density Estimation on, so is now a raster. I've classified these into 3 classes 15-50, 50-100, and 100-250 (there is also a 0-15, but I don't need this included). How would I go about creating contours at each of the limits of the 3 classes I want to keep? Martin - Deleting extra contours would be fairly time-consuming. The operation would preferably be done as a batch - they all have the same class symbology and they would all have the same contour limits too.

  • As @Martin said, the Contour function is the proper way to create these. Since you know exactly what contours you need, or don't need, it seems a simple select by attributes and delete selected features will do the trick, and not be overly time-consuming. – Get Spatial Sep 17 '13 at 14:55
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You should use the Contour function for converting a raster to contour lines. You can also define the base contour value and the interval between them (z-value).

Since you need to do this in batch, I would use Model builder. Iterate over your folder with rasters and use the Contour function. But instead of deleting excess lines, use an interval so large that it ensures no more lines will be created. Then let the model do this three times for each raster to get all levels you want.

Keep in mind that this function requires Spatial analyst or 3D analyst extension.

  • Hello Martin - thanks for your answer. I have the contour function. To clarify, what I need to do is the following. I need three contours, and the intervals are not constant. I need to contours to appear at the limits of raster classes I've already created. Is this possible at all? I understand the method described above, but the contour intervals are not constant - I think the above method wouldn't be suitable for what I want to achieve. – Joules Sep 17 '13 at 13:49
  • Not sure I completely understand your problem, but maybe you could just run the function three times with different base levels (and delete all other contours that are created each time). Adding a picture to clarify could help solving your problem. – Martin Sep 17 '13 at 13:55
  • I'll clarify above. – Joules Sep 17 '13 at 14:00

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