I have had absolutely terrific results with the Pix4D photogrammetric software, but have had to develop alternative workflows to using the Pix4D Capture app.
My principal issues with Pix4Dcapture app have been the lack of flexibility and control in planning a mission, and the fact that missions fail when downlink connection is lost, wasting precious battery time.
With Litchi, I can plan a mission at home using GIS software or Google Earth to develop a KML defining the flight line, then import the KML into a Litchi mission in the Mission Planner at flylitchi.com. Vertices on the KML line are imported as waypoints, and mission parameters such as individual waypoint altitudes, flight speed, waypoint turn radii are also set. When the mission is saved, it is automatically synced with the Lichi app on your device, even if you accessed Mission Planner from your PC.
When you fly the mission, you only need to make sure DJI-GO is not running on the device. Once the mission is uploaded to my Phantom3Pro, I set my camera to Interval Capture mode and start shooting when the first waypoint is reached. After the mission has uploaded and begun, the P3P will execute the entire mission autonomously, even if the downlink connection is lost or interrupted (which happens to me regularly).
Using this methodology means that you need to compute (or accurately estimate) your flight line spacing, interval timer capture rate, flight speed and flight altitude for a particular desired ground pixel size and image overlap. Learning to do this will help make you confident and successful. Hint: for the P3P I use a “conservative” 90deg. diagonal field of view; and the image size is 3000x4000, making the image diagonal 5000 pixel units wide. To digitize my grids accurately in ArcGIS, I use the “fishnet” command to build a grid with the desired line spacing, then snap to vertices while digitizing the flight lines.
For 3D object modeling, Litchi offers object-focused flight modes for circling at varying altitudes that look to be extremely effective for that purpose, even though I haven’t done that yet.