If none of the software that I try is able to manage to achieve what I would like them to I need to have another method of providing information to the user about various aspects of the exhibit. I must therefore overlay the video stream with another layer that gives the info, rather than have it integrated into the video itself.
The pressure pads work by sending a signal to the computer when two conductive surfaces touch. They could be placed under the terrain, and activate specific info when in a specific area. This however requires the terrain to be thin enough and the rover to be heavy enough to trigger the pads.
The conductive plates work by sending a signal to the computer when a wire underneath the rover makes contact with them. The biggest problem with this is that they would have to be on top of the terrain and thus visible.
These devices are often used in burglar alarms to detect whether a door is open or not, and could be modified to send a signal to the computer when a magnet underneath the rover passes above them. They could be above or below the terrain depending on the magnet strength, however, the activation area would be quite small and require the rover to be driven precisely over it to activate.
This would be a camera attached to the computer placed high above the exhibit, which would detect when the rover which is a contrasting colour to the terrain drives into a certain area of the exhibit. This is quite a complicated solution and requires being able to place the camera high up. It would also require re-exploring Pure Data again.