marshallair,
I have made some of these fields and below are a couple of links for you to get you pointed in the right direction... The stitching software is of greatest importance and I recommend PTGui (PTGui.com) as the best for the 360x180 panorama that is required. Autostitch (autostitch.net) can get you started but has limitations.
First is Nemo's sticky which lists several primary sources of info re doing the panoramas necessary to use photos of your own RC field as a photofield scenery in G3... scroll down to the Photofields section
http://www.knifeedge.com/forums/showthread.php?t=11067
The second set of links pertains to building your own 3-D field (rather than a panorama photofield) and making this type of field similar to your own RC field... See
http://www.knifeedge.com/forums/showthread.php?t=19348
The basic process is covered in the G3 Manual but this thread addresses how to find/incorporate various terrain features from within existing G3 3-D fields such as Sierra Nevada and how to use those terrain features in your own custom generated 3-D field...
Late in the above thread the discussion turns toward the actual geographical location which was used as the basis for features in the Sierra Nevada G3 field... It is suggested that Google Maps might be used to search maps of the original source geographical area (purported to be in Spain) to locate terrain feature sets similar to what might be required for a given custom field... The original location of Spain was identified and noted in an older post by GimbalFan
http://www.knifeedge.com/forums/show...=sierra+nevada
Charlie