Distortions and Artifacts in the Orthomosaic

Cause

The orthomosaic is generated based on the DSM that is created from the Densified Point Cloud. Thereby, errors and noise present in the Densified Point Cloud will be reflected in the orthomosaic. These distortions occur because Orthorectification is used instead of Photo Stitching, for more information: Photo stitching vs orthomosaic generation.

When computing the Densified Point Cloud, the altitude of the points will not be perfectly estimated. There are always some errors and noise that are minimized for good datasets (high overlap, good visual content of the images, use of GCPs, etc.).

These errors and noise result in altitude differences for points that are supposed to be at the same altitude, such as points that belong to the same roof edge of a building or the same edge of a bridge. This altitude difference explains the distortions that appear in the orthomosaic on building edges, bridges, etc.  

 
Note: The orthomosaic receives as input the DSM and the DSM receives as input the point cloud. If the point cloud is noisy, the DSM may also be noisy. Make sure that the results of step 1 and the point cloud are optimal before generating the DSM and orthomosaic.

Solutions

Orthomosaic before editing Orthomosaic after editing using the Mosaic Editor
Figure 1.
Orthomosaic before editing Orthomosaic after editing using the Mosaic Editor
Figure 2.

 

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3 comments

  • Hu Yuan

    pix4d is famous in the world ,should be begineer user easy to operation,but,i am a user,any setup correct or wrong ,i dont know how,HELP funtion too weak,when i  finishing project, i found progress not complete ,why,i rent your monthly for year,so expensive,

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    bestregards             afa8168@gmail.com                                                                                         by hung fu yuan TAIWAN

  • Holden (Pix4D)

    Hi Hung. Thanks for reaching out. If you are having issues with a project I would suggest opening a support request at support.pix4d.com. If you choose to open a support request please include a log file, quality report, and a description of the problem. 

    We are working to expand our supported languages so your feedback is helpful. Thank you.  

  • herbert.z

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