This article provides step-by-step instructions on how to merge projects in PIX4Dmapper. There are two parts when merging a project: Before merging projects and while merging projects.
It is possible to merge projects for which step 1. Initial Processing has already been completed in PIX4Dmapper. This allows the combination of information from different projects into one single project.
Merging projects is useful when:
- There are different image acquisition types, such as terrestrial, circular, and grid image acquisition types are used. This is very helpful when reconstructing an object which requires a terrestrial, circular, and grid images. For example, images obtained from a handheld camera and a drone can also be combined to generate detailed 3D models.
- The dataset is considerably large for the capabilities of the available processing resources.
Merging projects can speed-up step 1. Initial Processing time. It can also be used for projects having processing issues during step 1. Initial Processing with respect to memory use (not enough memory).
Before merging projects
- Create a new project for individual flights following: Create a project. We will call this the subproject.
For more information on how to split a project into sub-projects: How to split a project into subprojects.
- Process Step 1. Initial Processing for each subproject.
- Identify and mark a minimum of three manual tie points (MTPs) that have the same name and point to the same feature on both or all the subprojects. How to add / import and mark manual tie points (MTPs) in the rayCloud. It is very important for the MTPs to have the same name at the same location in all subprojects. If the naming is not consistent throughout the subproject, it can cause processing issues. Ensure the MTPs are located where the subprojects overlap.
- Reoptimize each subproject after adding MTPs and save them. Menu Process > Reoptimize
If a project is too large to be processed at once due to the processing resources, it can be split into subprojects.
1. Open PIX4Dmapper.
2. On the Menu bar, click Project > New Project..., the New Project wizard opens:
3. In Name, type a name for the merged project.
4. (Optional) In Create in: click Browse... On the Select project location pop-up, navigate to select the folder where the project and results will be stored and click Select Folder.
5. (optional) Select the check box Use As Default Project Location to save all new projects in the selected folder.
6. Selected the option Project Merged from Existing Projects.
7. Click Next.
8. On the Merge Projects page, the Duplicate camera parameters option is activated by default. If the camera model of the different projects is the same, it is duplicated by adding the name of the project at the end of the original camera model name.
9. Click Add projects...
10. On the Select Projects pop-up that opens, browse the project files. Select the projects to be merged (multiple selection is possible) and click Open.
11. Repeat step 9 and 10 to add more projects (if the processing resources can handle multiple projects)
12. Click Next.
13. Click Finish to create the merged project.
14. Automatically (no user intervention), the subprojects are combined and processed together. The final result of step 1. Initial Processing is generated.
15. Verify the Quality Report. One block should be created.
16. When the reconstruction consists of a single block, use the results to create another merged project, or start step 2. Point Cloud and Mesh and 3. DSM, Orthomosaic and Index.
It is very important that before merging, all subprojects are processed successfully and there are no issues reported in the initial checks of the quality report, e.g. bad camera optimization, uncalibrated camera, or multiple blocks.If possible, try processing projects with similar flight height and camera orientation together as one project rather than merging. This can simplify the process of getting the sparse point cloud to align properly.
Cases where the projects fail to align properly relative to each other are due to:
- There is not enough overlap between image acquisition plans.
- Make sure that each plan captures the images with enough overlap.
- Not enough matches between the subprojects.
- Add more common Ground Control Points or Manual Tie Points in the subprojects before merging.
The workflow for merging multispectral projects is different and is described here.