Yes, the n-D visualizer does not allow you to specify a mask for your input data. If you apply a mask to your data before you import it into the tool, then you've just changed the pixel values of the pixels under your mask. Those new values will still be part of the image, though. ENVI will not know that they are meant to be masked out. So, you'll see those pixel values in the n-D Visualizer. The NDV works with a region of interest (ROI) from the input file that you specify. So, it sounds like what you will want to do is create a region of interest that includes all of the pixel in your image, except the ones you were trying to mask out. If you need help figuring out how to create such an ROI, can you please let me know what logic you used to create your mask? You would probably need to use similar logic in ENVI's ROI Tool to define your ROI. - Peg

Thanks for the reply! The procedure that I followed to create the mask: I imported the full image into the n-D visualizer, selected endmembers of the unwanted materials and then merged these into one class/ROI. I then used this ROI to create the mask. When I created the mask, I chose Selected Areas Off and Selected Attributes [Logical OR]. I haven't been able to figure out how to create another ROI that includes all the pixels except what I want to mask, so any help would be greatly appreciated.