https://academy.hacking-lab.com/events/6/challenges/38
The Triangulation.stl can be opened on my Mac with Xcode. It shows a christmas ball.
As I've never worked in this environment with 3D models, I am zooming around and find quickly that the QR code is hidden as a 3D model inside the christmas ball.
So I'll have to get rid of the "outside"to be able to capture it in its entierty. I created QR.stl.
Using the open source 3D software Blender I was able to import the STL file and carefully delete all the vertices belonging to the christmas ball/hull. The resulting QR code couldn't be scanned with my iPhone camera app...
after trying to fix things (there was a missing vertice in the code making a small part non-square), I found out that the issue is not the data but my scanner: it seems as if the iPhone camera app doesn't read Aztec codes.
With the help of https://online-barcode-reader.com I was able to decode the message:
**19{Cr4ck_Th3_B411!}
The HV19 in the beginning was missing... therefore I had to amend this and was successfull with
HV19{Cr4ck_Th3_B411!}