3

I have a provincial sized DEM. I need to clip it to a fairly large watershed boundary. Should be easy. I've tried:

  • Data Management Tools -> Raster -> Raster Processing -> Clip

(Did I make sure "Use Input features for clipping geometry and "maintain clipping extent" where checked? Yup). Here's the error messages:

enter image description here

Says "No spatial reference exists" but it's a liar: enter image description here

  • Extract by Mask under Spatial Analyst tools doesn't work either.

I thought maybe my boundary shapefile was the problem. Created a new one using the draw tool, makes no difference. Shapefile set to same datum and projection as DEM.

The DEM itself won't project into a different coordinate system. It won't export - I've tried exporting to tiff, the png, to grid... an error always occurs. It is an unworkable DEM and I do not know why. I've clipped DEMs before no problem.

Can you see anything about this DEM that might make it behave this way? Here's it's properties.

enter image description here enter image description here

|improve this question
  • 3
    The software is a "liar"? Never anthropomorphize inanimate objects - they hate it when you do that. It's possible you just have a corrupt disk block. Try reloading the data from source and starting over. – Vince Jan 12 '16 at 16:03
  • just to make sure : have you checked the coordinate system of the other layer – radouxju Jan 12 '16 at 16:08
  • can you post the raster and polygon and link to it – If you do not know- just GIS Jan 12 '16 at 16:16
  • 2
    Vince had it right. I re-downloaded the data from the source. This solved my problem. Thanks – Megan Jan 12 '16 at 18:02
  • 1
    Megan add that as answer (and accept after 2 days). Self-answering is accepted and encouraged. – matt wilkie Jan 12 '16 at 18:29
3

It's hard to remember when under a crunch, but computer systems sometimes fail in partial or non-apparent forms. When you're being driven crazy by a an unexplainable failure, it's often best to lock the screen, take a quick walk about the floor or building, and work out a fallback procedure.

Ask yourself:

  • Could the data be bad? What other tool can I use to evaluate this possibility?
  • If the data is bad, where is my previous copy kept?
  • If I don't have a previous copy, where can I re-obtain this information?
  • If I can't re-obtain this information, what else might be usable as a replacement?

Then you can sit down and start to make progress again. Even if you have to take a few backward steps, the previous progress usually makes it easier to get back to where you were when things had gone bad (which is yet another reason to make extensive use of scripts to massage data, or to log the actions taken during a UI session so that reproduction is possible).

|improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.