For creating 3D models of city areas with photogrammetry software like RealityCapture from www.capturingreality.com and from portals like www.dronedeploy.com you need to acquire sets of images of an area with different angles:
1. Top down, like DH has now already.
2. 45 degrees tilted, looking forward (heading 0)
3. 45 degrees tilted, looking backwards (heading 180). This can be achieved of course by letting the drone fly the same track in the opposite direction if flying forward is more efficient than flying backwards.
2 and 3 can be combined in one run, if you overlap the images by 80% instead of 60%.
4. 45 deg tilted, looking 90 degrees sideways (heading 90). This can be achieved by creating a different path, perpendicular to the first one, like a double-grid.
5. Same, looking 90 deg sideways left (heading -90). This can be achieved by flying the perpendicular grid of item 4 in opposite direction.
4 and 5 can be combined in one run, if you overlap the images by 80% instead of 60%.
If this image set is still not sufficient to create a high quality 3D model, the mission could be expanded with 45, 135, 225 and 315 degrees heading. This could be a high-detail area capture mission.
DH can do this now more or less, but since the area you capture on camera shifts forward when you tilt the camera from top down to 45 degrees, the position at which the image is taken should be shifted back. For each camera pitch and yaw rotation, you get a different optimum snapshot location. So it would be good if you could create a mission type that does all that accurately, and combines these runs into one, to have the most efficient flight time, and avoid capturing unnecessary images that fall outside the desired area.
Since battery lifetime is probably going to be a limiting factor, it would be good if the mission included a return to home feature, to change the battery. Now, you can wait for the RTH function of DJI to set in, but after you change it, DH will not pick up the mission where it left off, in my experience (maybe this is a bug).
The newly added multi-Grid mission should do what you ask for here.
In addition after a battery swap you can chose to resume the mission by selecting resume in the launch dialog (in 3D preview).
We have not yet implemented a smart battery switch methodology. This is an open feature request (already registered here on the idea platform)