Hi ltasserie, I highly recomment that you contact ITT VIS technical support or your local distributor for SARscape questions. SARscape can get a bit involved, and you will probably get more effective help through those official channels, rather than here at the ENVI user's forum. I also highly recommend looking at the SARscape Help system for the tools you are using. It gives information about the type of data you can use as input, and the type of data you get as output, and describes all of the parameters. If you are doing interferometry, then you do not need to calculate multilooking, or coregister your master and slave images before starting the interferometric processing chain. You just specify the master and slave _slc files as you start up the Interferogram Generation step. Part of the internal process of that step is to coregister those images together. Multilooking is not a part of interferometric processing. If you want to coregister your images outside of your interferometric processing, then here are the answers to your questions: Yes, the output from the Multilooking tool will be intensity data (_pwr). It is fine to use these files as input to SARscape's Coregistration tool. The input reference file is whichever of your input files you wish to use as the reference image to which the other file(s) will be coregistered. It could be a _slc file, or it could be a _pwr file (or _pri or _sgf). So, in your case, it sounds like it would be the _pwr file output from the multilooking for your master image. You do not need your DEM file to have a _dem extension to use it as input to the Coregistration tool (you can change the filter in the file selection dialog to be *.* so SARscape sees files with any name). What you do need is for the DEM to have a SARscape header file (_sml). You can generate that by importing your DEM image into SARscape. For example, if it is an ENVI format file, you can use the tool under SARscape > Basic > Import Data > ENVI > ENVI Original. You can leave the field for the Shift Parameter file blank, as long as you check the box for "Compute Shift Parameters". In this case, the shift parameter file (_par) is computed as the first step in the Coregistration. The coregistration file is a file containing tie points to use if you wish to perform a manual coregistration. If you do not wish to do this, then you can leave this field blank. If you are still not getting good results, after considering this information, then it will be important for you to explain what does happen. For example, do you get an error message? What does it say? Do you output an error log file? You will want to send that to tech support or your local distributor. - Peg