Merge Projects - PIX4Dmatic


PIX4Dmatic allows for the merging of multiple projects into a single unified project. This can be useful when capturing aerial or terrestrial images from different flights or perspectives to create a single, comprehensive 3D model or orthomosaic.

What are the advantages of merging a project?

The advantage of merging projects is that it allows for different calibration settings to be applied to each subproject. These subprojects can have tailored settings for optimal calibration results. For example, a terrestrial project from PIX4Dcatch will use a different calibration setting than an aerial drone project. The Merge projects option then allows these customized calibrated subprojects to be combined to generate a single point cloud, mesh, DSM, or orthomosaic that has a higher level of detail and resolution.

Requirements Before Merging

PIX4Dmatic allows for combining multiple photogrammetric subprojects, that are geographically contiguous, into a single project. All projects to be merged should be well-calibrated before merging, and green checkmarks should be present in the Quality check.


*The GCP row will display a yellow exclamation mark when PPK/RTK projects are processed without GCPs.

Coordinate Systems and Accuracy requirements

Ensure the following requirements concerning coordinate reference systems and accuracy are fulfilled.

  1. The projects to be merged must have the same coordinate reference system, including both the horizontal and vertical coordinate systems.
  2. The projects to be merged must have either the positioning accuracy of a PPK/RTK device or be geolocated with the use of GCPs.
Note: PIX4Dcatch projects must be utilized with the viDoc RTK rover, or processed with GCPs. 

How to merge projects

Merging projects in PIX4Dmatic first requires identifying all projects that are to be merged. There are two ways to merge projects in PIX4Dmatic.

  1. Merge into an existing project: One project must be identified as the primary project. This is the project for which all other subprojects will be merged, and it is the project in which all successive processing will occur. There is no limit on the number of projects that can be merged, but only one project can be the primary.
  2. Create a new empty project: Click File > New project (or Ctrl + n), then import all the projects that need to be merged by clicking File > Merge projects. If all the Coordinate Reference Systems (CRS) are set correctly in all subprojects, no further action is needed. 

Required steps

  1. Run only the Calibration step for each project to be merged.
  2. Click Save after running Calibration.
  3. Identify a project to be the primary and open the project.
  4. In the primary project, click on File and Merge projects… to open the dialogue box.


    Merge projects dialogue box.

  5. Drag and drop the .p4m subproject files, or navigate to the .p4m by clicking Import from disk.
  6. After adding projects click Merge.
  7. After merging Reoptimize the project. 
    Warning: Do not run the Calibration step after importing and merging the subprojects. The subprojects have already been calibrated with their own calibration settings, and running the Calibration after merging will overwrite the initial results of each subproject.
  8. After PIX4Dmatic has been reoptimized, the Dense point cloud, Mesh, DSM, and Orthomosaic can be processed.

Frequently Asked Questions

What is the difference between merging in PIX4Dmatic and PIX4Dmapper?

The merge process in PIX4Dmatic differs substantially from PIX4Dmapper. There are two main differences between the two products:

  • PIX4Dmatic does not require the creation of an entirely new project. Rather, subprojects are merged into a single primary project.
  • PIX4Dmatic does not use Manual Tie Points (MTPs) for merging projects. Each project to be merged must hold the same level of absolute accuracy for the process to work correctly. For more information on absolute accuracy: What is the relative and absolute accuracy of drone mapping?

Can I merge a flight that was processed with GCPs with a PPK/RTK flight?

Yes, as long as they are on the same horizontal and vertical coordinate systems.

Can I merge projects that have different image coordinate systems?

Yes, as long as the output coordinate systems are identical.

Can I merge a LiDAR dataset with a project from PIX4Dmatic?

No, only photogammetric projects that were processed in PIX4Dmatic can be merged. However, PIX4Dcatch projects that utilized LiDAR from an iPhone or iPad can be merged, if they were processed in PIX4Dmatic.

Does merging projects require fewer system resources?

Merging large projects with a significant number of images can still be computationally intensive and may require substantial system resources, such as memory and processing power. For more information: Recommended hardware - PIX4Dmatic

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