Always make sure you’re flying with at least 70% overlap.
The basic principle of photogrammetry requires the matching of features between photos to form a single contiguous model. The images need to overlap — a lot — in order for features to be matched. The biggest culprit we see that makes aerial photos unusable is lack of overlap and it’s often the easiest issue to fix. In general you need a minimum of 70% overlap between photos to ensure proper alignment for processing. This means that for each subsequent photo taken in a survey, at most a third of the features its contains should be new.
Your flight control app should let you select the amount of overlap in your flights. Make sure you’ve got the right camera model selected, and try to use a high point on your site for take off — if you take off from a low point, you’ll end up flying low to the ground over higher areas and getting poor overlap.