Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am working with Erdas Imagine's Signature Editor to perform maximum likelihood classification. I need to use the same training set created in Erdas for other classification using R. Is there a way to extract the raster band pixel values under the .aoi polygons and export that information to a .txt or .csv? I am looking for the same functionality as the ArcGIS Sample tool where the individual raster band pixel values are extracted underneath points and written to a table (e.g. Figure 2). Alternatively, is it possible to export the signature editor table (i.e. including R,G,B,NIR bands and the class label) to a .csv? Any workarounds on how to integrate Erdas's signature editor with the analytical functionality of R would be very helpful.

For example, I need the functionality of the signature editor

Figure1 enter image description here

Yet I need to convert these values to a format that I can read into R. Note that I need all four bands of the input image along with a class ID (i.e. grid code). This table was generated in ArcGIS.

Figure 2 enter image description here

share|improve this question
Can you upload a sample of your sig file? I'd like to have a play around with the file, but don't have erdas installed in the office. Thanks. – sgrieve Nov 20 '12 at 9:10
@sgrieve I've uploaded the .sig to a file sharing – Aaron Nov 21 '12 at 3:59
Thanks, I've not had any joy pulling any data out from the sig file. I can't find any documentation on the format, so I am going at it blind unfortunately. Hopefully someone else will have some more luck. – sgrieve Nov 21 '12 at 9:24
I have been using this software ( to try and reverse engineer the sig file, but its trial and error to get the data in the correct format. – sgrieve Nov 21 '12 at 9:49

It has been a while since I used ERDAS, but I believe you can export .aoi to ASCII. In ERDAS, Utilities>Export pixels to ASCII. ?? Then you could load that into a CSV file. You can also convert your .aoi file to .shp, which you could then use with the ArcGIS sample tool you mentioned.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

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