IN THIS ARTICLE
To make sure that all the datasets capturing the same construction site are not shifted and to enable accurate measurements and comparisons, an alignment operation is required.
When a new project is processed, Pix4D uses an algorithm (ortho-alignment) which will find common points between an existing reference orthomosaic from a previous dataset and the new one from the new project.
As a result, the new 2D outputs (orthomosaic and DSM) will be shifted to match the reference one. The point cloud and 3D textured mesh will not be impacted.
- This algorithm aligns only the 2D outputs (orthomosaic and DSM) of each site. The point cloud and 3D textured mesh will not be impacted.
- When a new project is processed, the 2D outputs are aligned with respect to the latest reference project by finding common points.
- A project is marked as a reference if:
- It has the minimum number of images defined for each site. This number is defined internally by Pix4D considering the area of the site and the number of Crane Cameras installed.
- It has at least 80% of images with respect to the last reference project.
Workflow example for a site with a minimum number of images set to 100.
- The first project P1 of the site is processed on January 1st and has 120 images.
- P1 is marked internally as a reference by the Pix4D algorithm.
- A new project P2 is uploaded on January 2nd and has 60 images.
- The P2 will be aligned with respect to the latest reference project P1 but it will be marked as Low alignment confidence as the number of images is not 80% with respect to the latest reference project and it does not have the minimum number of required images. Therefore, it will not be a reference for future projects.
- A new project P3 is uploaded on January 3rd and has 105 images.
- P3 will be aligned with respect to the latest reference project P1. It will be marked as a reference for future projects as it has the minimum number of images defined for this site and it has at least 80% of images with respect to the latest reference project P1.
- A new project P4 is uploaded and will be aligned with respect to P3. It will be marked as a reference or as Low alignment confidence depending on the number of images.
The dataset will be flagged with the notification Low alignment confidence when:
- The dataset has fewer images than the minimum required number defined by the Pix4D algorithm.
- It has fewer than 80% of the images with respect to the latest reference project.
- The ortho-alignment algorithm failed.
The Low alignment confidence is displayed:
- With a warning icon on the Overlays and Annotations layers.
- With a warning message on the lower-right corner when the Overlays and Annotations layers are selected.
- With a warning message on the main page on the Compare mode.