Avebury Henge has a diameter of 347 metres (and the largest in the world).
I’ve always wanted to do a top-down shot with a drone, but to get it all in, I would need to fly to an altitude of at least 900 metres.
This was validated using Google Earth Pro.
This is what Avebury looks like at 120 metres altitude:
Since 900 metres altitude is 7.5 times the legal altitude limit for drones in the UK, I decided to take the panoramic approach.
The DJI Air 3 includes Waypoints. I have tried to create waypoints prior to the flight on a few occassions, but the screen is too small to create anything complex. The alternative method would be to fly to each waypoint, save it, and then start the flight from the 1st waypoint. But with the size of Avebury, it would mean a flight time of an hour - which is impossible. I could save the waypoints for later, come back, change batteries, then do the flight … but it’s too much faff. This is where Litchi would really come in handy, but since I have the DJI RC, so I can’t install it.
So I decided to do the whole thing manually with the Air 3.
- Took off from the Herepath (51.429759, -1.849673)
- Climbed to 120m
- Set the camera to timed photo mode @ 5 seconds
- Took my hand off the left stick
- Tried to keep the speed to 10 mph
- Flew 12 passes over Avebury Henge
- Took 280 photos
- Returned to home
Airdata shows the following for the flight:
It was quite windy up there to:
I downloaded the KML and viewed in Google Earth Pro:
The 280 DNGs were then loaded in Autopano Giga. It took 24 minutes to create a preview of the stitched 280 photos. But due to the size of it, AGP warned me that it would result in a PNG with a file size of more than 2GB, and due to PNG limitations, it could corrupt.
- Size = 32,148 x 34,874 = 1,121,129,352 pixels
- Pixel count = 1.12 GP pixels
- Resolution = 1.12 GP pixels
So I reduced the settings by 40% and then rendered the pano. This took about 30 minutes and still ended up creating a 1.95GB PNG. The image resolution is now:
- Size = 19,288 x 20,924 = 403,582,112 pixels
- Pixel count = 403.58 MP pixels
- Resolution = 403.58 MP pixels
- Size = 1.95 GB
It is available on WeTransfer for the next 7 days in case anyone wants a play.
I then loaded the 1.95 GB file in Photoshop, edited it, saved back to the PC.
After a SHED LOAD of faffing trying to upload to GADC ...
But this resulted in a file of 506 MB, way too big to upload to GADC. So I then saved it as a JPG, but that too was 106 MB, over the 100 MB upload limit for this forum. I reduced the scale by 2%:
- Size = 15,524 x 16,247 = 252,218,428 pixels
- Pixel count = 252.22 MP pixels
- Resolution = 252.22 MP pixels
- Size = 97.5 MB
I tried uploading it to the forum, but it failed, with a warning stating:
Sorry, the image you are trying to upload is too large (maximum dimension is 200-megapixels), please resize it and try again.
I then reduced the image scale by 5%, which meets the 200 MP and 100 MB file size restrictions:
- Size = 13,543 x 14,174 = 191,958,482 pixels
- Pixel count = 191.96 MP pixels
- Resolution = 191.96 MP pixels
- Size = 71.6 MB
But it still wouldn’t upload, and errored with:
/var/www/discourse/lib/discourse.rb:138:in `exec’: An error happened when converting from PNG to JPG.
After a lot of trial and error, the only thing that worked was to reduce the image resolution by 50%.
- Size = 9505 x 9947 = 94,546,235 pixels
- Pixel count = 94.55 MP pixels
- Resolution = 94.55 MP pixels
- Size = 17 MB
Which suggests to me that the maximum dimension permitted is actually 100 MP, and not 200 MP.
Below is a 280 image pano of Avebury Henge 
