For First Principal...
FP, I see where you are coming from and understand that you have the technology with and for a MAG survey but the problem would be and will be the required "nearness" of the detector to the source, the subject it is trying to detect. The trees will get in the way.
Although the loggers leave a trail of destruction like you would not believe the trail or damage itself is detectabe even in Google Earth as you can see the verbiage has a different shade of green where they have rampaged through the area knocking, chain-sawing and crushing. From SAT photos that are embedded with LAT/LONG and viewed in Adobe I can follow the ridgeline bulldozer track just by the colour change of the green tinge or by the greyscale change in a black and white SAT view.
There are very few glimpses of the ground in a SAT view except on "Zoom Earth" outdated SAT pics you can see where the Logging Company had literally knocked over "everything" (there are logs to be seen lying on the ground) in their attempts at 're-aforestation' and those attempts are showing up on Google Earth as a "different shade of green" as the new trees they plant are Kamarare Trees and the blocks they have planted show up as plain as day on Google earth in the Wide Bay area just back from the coast by the different shade of green.
On the hill, I would say that where they have been, the trees left standing that they have not taken because they are less commercial value will be up to 100 feet tall (30 Metres) so a drone would have to be pre-programmed to stay above a height of say 125 feet above the trees, plus the ground level height. The next problem is that the hill ridgeline is not level.... it increases in height the further it goes to the West so the drone would have to have a safety factor let in there, say 200 feet altitude above the trees, just in case it clonks into an exceptionally high tree.
That to me, would be the problem.
We did at first consider a LiDAR drone and in that case the drone height would have been say, 1500 feet to clear both the trees and the ground level altitudes which due the to slope on the ridgeline would vary, end to end...
Last edited by David Billings; 28th Feb 2018 at 16:06.