Pix4DField has some planarity assumption but actually makes a decent job as long as a single plane can be seen (most likely the ground). Sure, it is not suited for many cases, but as you found out, its speed is unbeatable. I agree that’s a nice piece of software with some neat algorithms.
Comparing with Pix4DMapper would be a fairer comparison.
But again, you’re comparing a multi-million company with several dozens of developers working 8 hours a day, with an open-source software where most people usually spend these 8 hours for another company.
Nevertheless, as one of the OpenSfM contributors, I have ideas for better and faster handling of planar scenes, but as mentioned, it’s about time, days are only 24 hours.
This paper is a good candidate : https://people.eecs.berkeley.edu/~yima/psfile/Planar-CVPR12.pdf OpenSfM has everything, we just need to implement the track construction trough homography linking, get the homographies for each image, recover translation and rotation, triangulate point on the plane and then bundle. Would be much faster than the current incremental SfM. 2-3 weeks works, I guess.