When Step 1 processing produces more than 1 block, what is the best way to ensure that I'm adding manual tie points in a way that will help stitch those blocks together?
When I'm merging subprojects that exactly overlap with each other (same survey area, but cameras with different spectral/spatial resolutions) and 2 blocks are created, it is obvious in the rayCloud that there are two "layers" to the point cloud and putting the manual tie points evenly spaced throughout the survey area enables Pix4D to properly stitch those layers into a single block.
What if more than 1 block is created in a project where there isn't this obvious "2 layer" effect? Is there a way to visualize what areas of the surveyed area have been assigned to each block, so that I can create manual tie points along the seams between them and stitch them together in a single block?
I've attached an example quality report overview showing that 4 blocks were created (Figure 1), and the layout of the image captures showing an even spatial distribution of the images (Figure 2). This project was processed with a keypoints image scale (in Step 1) of 2. The same project was processed with a keypoints image scale of 0.5, which resulted in 2 blocks. Figures 3 and 4 are the equivalent parts of the Quality Report as Figures 1 and 2, but for the processing that used the keypoints image scale of 0.5.
Figure 1. The Quality Report overview of the processing. There does appear to be a bit of a streak of different reflectance in the left hand side of the "Preview". Maybe different lighting conditions for that flight? Maybe that's creating different blocks?
Figure 2. The spatial distribution of the image captures and the manual tie point positions.
Figure 3. Same as Figure 1, but with keypoints image scale (Step 1) set to 0.5
Figure 4. Same as Figure 2, but with keypoints image scale (Step 1) set to 0.5