Processing Large Datasets

Pix4Dmapper is able to simultaneously process an unlimited number of images. However, depending on the dataset and the processing resources, there might be some issues with datasets larger than 2000 images. This is an indicative value, as processing depends on the image resolution, image content, overlap between images, chosen output resolution and computer used. 

Large datasets can be taken with:

  • One flight for aerial projects.
  • Multiple flights for aerial projects.
  • A car for terrestrial projects (mobile mapping).
  • A tripod or by hand for terrestrial projects.

If the dataset consists of more than 2'000 images, it is recommended to divide the dataset into multiple datasets, process them separately and then merge them.
Two cases can be distinguished:

Having image geolocation 
Not having image geolocation

Having image geolocation

When having image geolocation, the Split into Subprojects option can be used to create the multiple subprojects.

1. Create a new project that consists of all the images of the large dataset. For more information: 202557369.
2. Split the project into subprojects. For more information: 204700835.
3. Run step 1. Initial Processing for each sub project.
4. Check the Quality Report for each subproject. For more information about how to analyze the Quality Report202557339:

    • If the quality of the reconstruction of all subprojects is good and consists of one single block, go to step 5.
    • If  the Quality Report indicates that there are problems with the reconstruction of one subproject, check the Quality Report Help: 202558689.
 
Tip: Add GCPs (202560239) and/or Manual Tie Points (202560349) on each subproject. The GCPs and/or Manual Tie Points should be homogeneously distributed in the common area of the subprojects. There should be at least three common GCPs and/or common MTPs marked on each subproject. Then, Reoptimize (202557809) and check the new Quality Report (202558319) for each subproject.

5. Merge the subprojects. For more information: 202558529.
6. (optional) Click Process > Reoptimize.

 
Important: The different subprojects created with the Split into Subprojects option contain common images in order to ensure overlap.
 
Note: If there are GCPs in the project, it is possible to include them in the subprojects or in the merged project. For more information about how to include the GCPs in a project: 202560239.

Not having image geolocation

When there is no image geolocation, the dataset should be divided into subprojects manually. For more information: 204217299.

Having more than 3 GCPs per Subproject

1. Create a new project for each subproject. For more information: 202557369.
2. Run step 1. Initial Processing for each subproject with the same Keypoints Image Scale for all subprojects. For more information: 202557759.
3. Add at least three GCPs on each subproject. The GCPs should be homogeneously distributed on each sub project. For more information: 202560239.

 
Warning: Only GCPs that are common in the different subprojects should have the same label. GCPs that do not represent the same point in the different subprojects should have different labels.


4. Click Process > Reoptimize for each subproject. 
5. Verify the Quality Report for each subproject. For more information about how to analyze the Quality Report: 202557339:

    • If the quality of the reconstruction is good for each subproject and consists of one single block, go to step 6.
    • If  the Quality Report indicates that there are problems with the reconstruction of one subproject, check the Quality Report Help: 202558689.

6. Merge the sub projects. Fore more information: 202558529
7. (optional) Click Process > Rematch and Optimize.

 
Important: Projects can be merged only if the GCPs defined in the different subprojects are in the same coordinate system.

Having less than 3 GCPs per Subproject

1. Create a new project for each subproject. For more information: 202557369.
2. Run step 1. Initial Processing for each subproject with the same Keypoints Image Scale for all subprojects. For more information: 202557759
3. Add GCPs (202560239) and/or Manual Tie Points (202560349) on each subproject. The GCPs and/or Manual Tie Points should be homogeneously distributed in the common area of the subprojects. There should be at least three common GCPs and/or common MTPs marked on each subproject.
4. Click Process > Reoptimize for each subproject. 

 
Example: For an aerial project:

 
Important:
  • Use the same label for the common GCPs/Manual Tie Points for all subprojects. For more information about how Pix4Dmapper treats the MTPs during merging: 202559439.
  • If less than three GCPs are used for the merged project, then they are not taken into account as GCPs. 

5. Verify the Quality Report for each subproject. For more information about how to analyze the Quality Report202557339:

    • If the quality of the reconstruction is good for each subproject and consists of one single block, go to step 5.
    • If  the Quality Report indicates that there are problems with the reconstruction of one subproject, check the Quality Report Help: 202558689.

6. Merge the subprojects. Fore more information: 202558529.
7. (optional) Click Process > Reoptimize.

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