4

I am wondering if there's another way to convert raster data (ex: DEM) into regularly sampled points. I've used Raster to Point under ArcToolbox previously, but if the raster data is huge, that's a lot of points! Is there a way to specify the number of points or to specify the cell width and height so they're nicely spread out? I am aware of the Create a Fishnet tool, but that doesn't seem to be working for me at the moment. Not sure what I'm doing wrong.

  • For one interesting (and powerful) approach, you can adapt an R-based solution. Ultimately, what do you intend to do with this sample? If you want to compute univariate statistics you might be better off with a purely grid-based solution (which I would be glad to describe), whereas if you also need the coordinates of the points, conversion to vector format does look appealing. – whuber Jan 19 '12 at 22:45
6

Alternatively, you could proceed as followed:

  1. Use the aggregate tool on your input data to create a coarser raster with the same extent.
  2. Convert the resulting raster to points.
  3. Use these points to sample the original grid.

The key here is the aggregation factor which controls the degree of generalization of your input data, e.g. the spacing of the resulting sampling points.

  • 3
    (+1) If you use nearest-neighbor resampling, the aggregated grid is the desired sample: no need for step 3. – whuber Jan 20 '12 at 2:10
2

If you have Spatial Analyst, here's what I would suggest:

  1. Create a set of square polygons of your desired dimensions using the Create Fishnet tool, and using your raster as the extent. You only have to fill in either the Cell Size Width/Height or Number of Rows/Columns fields.

  2. Use the Feature to Point tool to get the centroids of each of the fishnet cells.

  3. Use the Extract by Points tool to grab the raster values sharing a location with the centroids you created.

The output will be a point feature class, with the sampled raster values as attributes.

EDIT: In fact, I think step 2 can be omitted if you use the "Create Label Points" option in the Create Fishnet tool. (I'm assuming the label points are created as centroids.)

1

You can also resample your raster to different cell size and then use raster to points. All depends on what do you want receive as final product.

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.