Hi folks, I'm due to have another go at a photogrammetry survey with my H520. This one is of a dam in Wales which obviously slopes quite steeply. I'm looking for some general guidance/pointers, mainly around altitude. When planning it in Data Pilot, the altitude is said to be 'relative'. I assume this is relative to the take off point? My concern is that as I start working down the damn, if I've set my altitude relative to the take off location at the top of the dam, as it works its way down, it will be too high. In other words, if I'm at 50m at the top of the dam, and the dam is 100m high, I'll be at 150m altitude at the bottom of the dam. Can I get it to decrease altitude as it works its way down? I'm afraid that this will affect how the images are stitched together. Or will it just work itself out? Any other pointers gratefully received.