I am not clear on what kind of data you have - do you have a stereo pair of WV-2 or do you have actual epipolar images, which are derived from a stereo pair? ENVI's DEM EX does not support external epipolar images, so they must be generated during the DEM extraction process. If you are having difficulty using a stereo pair of WV-2 images in DEM EX (or 3D cursor), it may be the way they are opened. Perhaps you need to open them using "Open with RPC positioning" so the RPCs are recognized when importing the data to the module.

It is a stereo pair MariM. Actually, it's a large area divided into 7 "tiles" of stereo-pairs and I'm finding that one of the tiles is giving very poor results for elevation computation (the region becomes increasing mountainous and it is heavily forested). Perhaps I could mosaic them together before I conduct the DEM extraction? We had a dataset from Geoeye which I thought was stereo-pair as well, but in that case ENVI recognized the dataset as epipolar imagery. Perhaps Geoeye delivered the data as an epipolar dataset. Regards, and thanks for the communication!

You may stitch the tiles of World View -2 in ENVI. Go to ENVI main menu bar > File > Open External File > World View > Mosaic Tiled World View Product > choose .TIL file and mosaic all tiles to make a single image. This way you can create mosaicked stereo pair. There is no inbuilt epipolar is available. To generate DEM you have to create Epipolar. Go to ENVI main menu bar > Topographic > DEM extraction > DEM extraction Wizard > New > follow the steps. As an intermediate step you will get epipolar and as an end product you will get DEM. Please let me know how it goes.