Pix4Dmapper relies on visual similarities between overlapping images to reconstruct the model. Trees and dense vegetation, due to their complex geometry (thousands of branches and leaves), often appear very different between overlapping images. Therefore, it is more difficult to find enough similarities between overlapping images and, if the overlap is not enough, it leads to issues in the calibration.
In these cases, it is recommended to:
- Process with 1/2 Keypoints Image Scale: This processing option can lead to a higher number of calibrated images in case the default option (original keypoint image scale) does not calibrate all the images. For more information: Menu Process > Processing Options… > 1. Initial Processing > General.
Increase the overlap between the images to at least 85% frontal overlap and 70% side overlap.
Increase the flight altitude : When flying higher, the images suffer less from perspective distortions and it is easier to detect visual similarities between overlapping images in vegetation areas.
For more details about the flight plan: Step 1. Before Starting a Project > 1. Designing the Image Acquisition Plan > a. Selecting the Image Acquisition Plan Type.
If changing the processing options does not solve the issue, please upload the Quality Report here and we will have a closer look.