Force MTP correspondence between multiple blocks?

PIX4Dmapper
1

For years I have been dealing with the multiple blocks issue in Pix4D. When I mark an MTP belonging to two separate blocks, is there any way to force correspondence upon Reoptimize? Same question with adding GCPs. It seems that the blocks are very stubborn despite my high confidence in marking the same point from different blocks.

I wonder if the issue is in GPS accuracy. If I momentarily flew too close to trees, the GPS and therefore initial camera position might have gotten thrown off. Are the cameras not allowed to violate the specified horizontal and vertical accuracies? It could be that upon attempting to Reoptimize, the block’s cameras are running up against a hard position constraint. After all, it seems simple to rigidly superpose two separate blocks given 3 or more MTPs.

2

Hi Evan,

The MTPs should pull the blocks together. Without seeing your project, it is a bit hard to comment on why it is not doing that. However, you asked about the geolocation of the images. If you use the Accurate Geolocation and Orientation calibration option, then it could cause this problem as Mapper will place more weight on the positions of the images as compared to Standard calibration.

Since you are encountering this quite often, what overlap settings are you using? It sounds like you might need to tighten up your flight lines. Perhaps increase overlap to over 80%.

3

Hi Mike,

I hand-flew multiple flights for this project. It was a roadway in a city environment. Shadows were changing, some flights were low to get buildings, etc…

I finally solved the issue by locating the problematic images causing the block and unchecking them in Image Properties. I think this will be my first debugging procedure in the future rather than the seemingly unproductive iterative process of adding MTPs between blocks, which just keep getting overridden anyway by the processing, despite high confidence in the manual match between blocks.