Multiple blocks / Vertical Inaccuracies - PIX4Dmapper


There is more than one block of calibrated images after processing step 1 in PIX4Dmapper.


A block is a set of images that were calibrated together. Multiple blocks indicate that there were not enough matches between groups of images to provide global optimization. When a project contains multiple different blocks they may not be accurately georeferenced relative to each other. A project should ideally contain only 1 block. See below for how to check the number of blocks within the quality report.



There are several causes that can lead to this issue:

  1. The project consists of multiple flights which were flown at different periods, different heights, with different cameras.
  2. There is not enough overlap between image acquisition plans.
  3. Corridor projects can exhibit this issue if images were not acquired correctly.
  4. The terrain is flat with homogeneous visual content such as agriculture fields or snow, sand, and water.
  5. The project area consists of forest and dense vegetation.
  6. Incorrect calibration method for the terrain and image dataset.


Possible solutions to the previosly listed causes are proposed below.

For cause 1:

  • The flight height should not be too different between the flights, as different height leads to different spatial resolution. For more information: Can PIX4Dmapper process Images taken at different Flight Heights?.
  • Try to fly with the same lighting conditions, same hour of the day, same sun direction, same weather conditions.

For cause 2:

  • Make sure that each plan captures the images with enough overlap.

For cause 3:

For cause 4:

For cause 5:

For cause 6:

Tip: It is recommend adding common Manual Tie Points between the blocks in all the mentioned cases above. For more information: How to add/ import and mark manual tie points (MTPs) in the rayCloud