Can facade capture mission images be merged with regular more nadir imagery to create a new project and will they help make for a better 3D building model?
In theory it should work but I don’t know how well DroneDeploy has tuned their algorithm to eliminate point noise from images that have too much background or even the horizon. The other thing that could make it a bit tricky is if the difference in GSD between the normal map images and the structure gets too large you could start seeing some really strange effects. If you are mapping images are 200 ft above ground and your facade is only 50 ft away from the structure it creates a lot of complicated math and points in order to stitch the vastly different viewpoints.
I often fly and process data from two flight plans at different altitudes but understand that imagery with horizon (which I would think facade imagery can’t avoid) often causes issues in processing. I also have wondered if it’s possible to take the point cloud output from the two different flights (a regular drone nadir flight and a facade capture) and merge them in something like blender or Cloud compare to make a new point cloud with both sets of point and then try to create the mesh in blender for best results. the facade point cloud can be edited to only include the facade points. The problem would probably be registering the two flights but might not be an issue if you add a few GCPs or checkpoints to the facade that is captured in both flights.
This is pretty common in a couple of scenarios. For us it is to keep the structural 3D model separate from the terrain model. We can them both up and then merge them in Carlson Precision 3D Topo. By trimming everything outside of the building on the structural point cloud we can cleanly insert it into the DTM’d terrain. Another case is flying tracts larger than what DroneDeploy can process and export. We use to do it with sites with allot of elevation change but Terrain Awareness fixed that.
As far as different altitudes we have seen trouble in processing when we get more than a 150-200ft delta between the two flight. We have a project that we have to fly at 265ft because of tower cranes but I did the obliques around 50ft off the structure and it failed the first time. DroneDeploy fixed it on their end but the windows and roofs obviously had a little trouble cleanly stitching. If it’s only about 100ft it seems to do fine which works for the majority of our projects as tower cranes are not very common in our scopes.
I often fly two different elevations but I don’t always process in DroneDeploy. The elevation differences are not too drastic usually less than 100 ft. Sometimes a circular flight plan around a building as well as a mostly nadir flight over the building.