Rule based feature extraction has a lot of steps that have a potential for errors depending on input or lack thereof. You didn't mention at what point the error occurs or what you were doing. Perhaps the following article can help clarify the workflow and parameter settings you may need to adjust: http://www.exelisvis.com/...uleBasedTutorial.pdf

Hi, Thanks a lot for your reply! The image I used is a gray level aerial photo in tif format. After I set the segmentation level and merge level, ENVI starts segmentation and computing attributes, then click next, the window of creating rules shows up, meanwhile, an error message window pops up saying "Internal error: OBJ_NEW. Checking the creating rules window,I find that all attribute values are zero and the histogram button is disabled. I have read the pdf file you provided (thanks!), and do not see something wrong. Actually,only two steps I have run, which are setting the input file and segmentation / merge scales. I also tried other satellite images, the same thing happens. Have you experienced this kind of things and do you have any suggestions? Thanks again!

What version of ENVI 5 are you using? Perhaps installing the latest version ENVI 5 SP2 will fix the problem. If you have that installed then I would suggest you get in touch with technical support and provide full details of the problem including the exact steps you are following details about the file ie the dimensions, file type (*.tif) etc. and any setting you use up to where the error occurs. Also let them know your license/installation number.

Thanks a lot!