1. Context

For some specific projects, the photogrammetry is launched outside the platform. In that case, calibrated images metadata, calculated during the aerotriangulation process, will not be processed by the platform. However, some functionalities need these calibrated images metadata to work properly. That's the case for managing the proximity filter in 3D and the projection of 3D annotations on 2D images.

This article explains how to import post-aerotriangulation images metadata. 

2. Description of calibrated images metadata

There are 2 types of calibrated metadata : 

– internal camera parameters, which depends on the sensor, and are identical for all images taken with the same sensor:

• focal length 
• pixel size 
• principal point
• radial distortion [R1, R2, R3] 
• tangential distortion [T1, T2]

– external camera parameters, which vary from one image to another : 

• image unique ID 
• camera 3D position [x, y, z] 
• camera rotation [omega, phi, kappa] 
• image width and height 

3. How to import calibrated images metadata

To import these calibrated images metadata, open the related survey in Data Studio, and open the “Images” sub-menu. 

Click on the “i” button to open the “flight” panel if not already opened. 

Click on the “…” on top of the “Flight" panel, and select the option “Import post-aerotriangulation metadata”.  

It opens the following pop-up : 

The user must select 2 files : 

• one for internal camera parameters
• one for external camera parameters. 

3.1. Format of internal camera parameters file

The expected format for the internal camera parameters file is described below. It corresponds to the pix4D export format, and can be exported from Metashape or Pix4D directly in this format. 

3.2. Format of external camera parameters file

For images, 2 formats are supported. Both formats are described below: 

• File exported from Pix4D

The file exported from Pix4D contains 1 header describing the columns: Image Name, longitude, latitude, altitude, Omega, Phi and Kappa. Angles are in degrees.  

• File exported from Metashape 

The file exported from Metashape contains 2 headers, one with the number of pictures, and one with the list of columns. Only the columns PhotoID, X, Y, Z, Omega, Phi and Kappa are parsed. The other columns are ignored. Angles are in degrees.  

To be associated to images, the “PhotoID” or “ImageName” columns shall contain the name of the pictures of the survey. Otherwise, there will be a warning message : 

If the file format is not recognized, an error message will also be displayed. 

Once the two files selected, the user can click on “CONFIRM” to validate the import of calibrated image metadata. If calibrated metadata are already defined on images, there will be a warning to inform the user that existing metadata will be replaced. 

If the user confirms, the new calibrated metadata are saved, and all 3D functionalities will be fully operational.