Merging multispectral projects in Pix4Dmapper

Instructions for merging multispectral projects or merging a multispectral project with an RGB project so that the reflectance maps align with the RGB orthomosaic.

Marking MTPs in multispectral project

The full workflow for merging projects in Pix4Dmapper is described in How to merge projects article.

However, the difference for a multispectral project is that the MTPs need to be marked in each band for each image, e.g. if the MTP1 is marked in an image of the Green band, it will also have to be marked in the Red, Red edge and NIR images that correspond. Hence, what would be one mark in an RGB project results in four marks in a multispectral project (if there are four bands). In addition, you have to mark your MTP in at least three sets of images. Therefore, there should be at least twelve (3*4marks) for each MTP in the project.

Once all MTPs are added, click Menu Process > Reoptimize to apply the changes.  

Use of radiometric targets in merged projects

Pix4D supports only one set of radiometric calibration target images.

In order to get merged reflectance maps, we recommend unselecting duplicate parameters as mentioned in Step 8 of the How to merge projects article.

 
Important: If duplicate parameters option is selected, multiple radiometric targets can be used, however, the reflectance maps will not be merged. For example, when merging two Micasense projects with five bands, ten reflectance maps will be generated. Hence this procedure would not be of your interest because you will get no extra benefit compared with processing projects individually. 
Note: If you have two flights, we recommend using the target images that were captured after the first flight and before the second flight.
However, if the weather condition between those flights were different, we suggest processing the projects separately and then merging the reflectance maps in QGIS/ArcMap.
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