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Pix4D - 3DR Edition: Question about Geo-referenced Orthomosaic (2-Dimensional)

Hello-

Apologize if this question has been asked before, but I need some clarification. Let’s say I collect GCPs (X,Y,Z) for a mapping project and use these GCPs to process a Geo-referenced orthomosaic.

Will the Pix4D 3DR Edition software take the Z into consideration when processing, thus geometric corrections will be applied for X, Y, and the Z axis? (Understanding that the 3DR edition will not output any 3D products like DSM/DTM).

Just want to be sure I’m not missing something because to me the terms Orthomosaic and 2D seems like two different concepts. Thank You in advance!!!

Jason.

Hello Jason,

In order to generate the orthomosaic, the DSM should be generated, which is a 2.5D output, meaning that for each horizontal point only one Z can be computed. In order to generated the DSM the point cloud is needed, which is a 3D output. Therefore, in order to generate the orthomosaic, the model should be reconstructed in 3D.
So, if you plan to use GCPs for georeferencing the models (which is recommended), you should use all 3 coordinates.

Also note that the 3DR Edition only generates the Orthomosaic as an output. The orthomosaic is a 2D ortho projection of the area that has gotten rid of the perspective distortions and therefore, distances are maintained and can be accurately measured.
For a comparison between Pix4Dmapper Pro and 3DR, please check: https://support.pix4d.com/hc/en-us/articles/204162839

Best regards,