Using polarization in a photogrammetry scanner

*** 2025 UPDATE: A MORE COMPREHENSIVE VERSION IS NOW AVAILABLE ON https://doc.xanglecs.com/Cross-polarization-1bfd2d30a5dd80dea0f4dde5eb753325 ***

Adding polarized lights is a great way to improve the texture of your model at rendering time. Here’s how we manage to do this with no custom hardware components (electronic boards)

Face scanner configuration

• Group A: 89 Canon SL1, 4 Profoto D1 1000w (bounced light), one sacrificed SL1 with a pocketwizard on the hotshoe (channel 1, sending the signal to the Profoto lights)
• Group B: 6 Canon SL1 with a circular polarizer, 5x Godox lights with polarized gels, one sacrificed SL1 with pocketwirzard on the hotshoe (channel 2, sending the signal to the Godox lights)
• All cameras connected to Xangle Camera Server (95 cameras detected) - Same settings everywhere

The main challenge in this setup is to trigger both groups rapidly one after the other to ensure minimal subject movement (ideally within 1/16s). We also want to have both sets of pictures inside the same folder to ease file management.

From Xangle, we set the shutter speed to 1/60s and we created a custom trigger sequence to delay Group B. There’s only 20ms between the triggering of Group A and Group B. The sacrifice camera is used to fire the strobes half way during the exposure of their related group.