In Belgium everybody uses Belge 72 coordinate system. How can we properly import the RTK drone photos in 3Dsurvey, so that we will be able to take best advantage of drone's RTK gps?

Because a special grid transformation must be used between WGS84 and Belge 72 coordinate system, we must use this workflow:

Prerequisite steps - install additional free softwares:
a) Install cConvert tool for conversion between ETRS89 and Belgian Lambert 72:
https://common.ngi.be/static/cConvert.exe
b) Install Matlab MCR:
https://drive.google.com/file/d/0By8mtXeuby0wODVuRUpPMDQtZUU/view?usp=sharing
c) Download ExifExtractor_WGS.exe:
https://drive.google.com/file/d/1doJeP4T67YCeerw8EshG0C8o6iAsPfap/view?usp=sharing

Workflow for setting up the project:
1.) Load in the images and set up the project like this:

2.) Run Exif_Extractor_WGS84.exe click on Load RTK from Photos, and then save the txt file with ETRS Positions:

3.) Run cConvert app, and use the file exported from previous step as input, and use these settings:

4.) In 3Dsurvey click on Reimport in telemetry view:
(To get the telemetry window, click on Data/Telemetry in menu bar)

5) Select Other as data type, then click on Browse to load in the Belge 72 coordinates from cConvert, and set everything up lik this, and finally click on Reimport:

This will overwrite the XYZ values for telemetry and move the camera postition accordingly. Then just process the project normally.