When ENVI Reports: "Array dimensions must be greater than 0"

When performing any type of processing that takes ROIs as input, sometimes users will encounter an error like this:

     An error has occurred during processing

     Error: "Array dimensions must be greater than 0." The result may be invalid.

This error message usually indicates that one or more of the ROIs specified for the processing contains no pixels.  For example, perhaps a ROI has been drawn, but has not yet been accepted. You usually accept a drawn ROI by right clicking after drawing the ROI, and choosing Complete and Accept Polygon. If you choose to only Complete the polygon, and not Accept it, then there will not be any pixels in the ROI until that polygon has been accepted by right clicking again and choosing Accept Polygon.

When creating ROIs in ENVI, you can see how many pixels they currently have by clicking the Area tab at the bottom of the Region of Interest Tool dialog. If the area shows 0 Pixels, and you try to use that ROI in some kind of processing, then you will probably get "Array dimensions must be greater than 0" error message.

Review by MMin, 2015-02-12