Hi Jim, thanks a lot for your reply. I tried the method you suggested, it worked to convert the 2D AOI to 3D AOI. However, I'm confused with the resulted 3D AOI. It appears a little higher than DTM. When I turn on DTM and 3D buildings layers, it looks normal. However, when I turn on 3D AOI and 3D buildings, some short buildings disappear (hidden under 3D AOI). Would you know how possibly I can fix this? Thanks