Precision photogrammetry for stonemasonry: old meets new...and goes digital - Vaireco - Ken Varner

Hi everyone,

To open the 2018 #3DMonday season, we have an amazing project where accuracy meets photorealism:

Click here to pull measurements from the model on Pix4Dcloud

Grab you VR headset and Click here to see the project on Sketchfab

This is the story of this project in the words of its creator:

For this historic building in Germany, we were contracted by a stonemason under the following conditions:

1: The model’s resolution must be fine enough to examine cracks in the stone and perform damage analysis

2: Any measurements pulled out of the model must be within 2 mm of accuracy

In order to achieve this goal, it was necessary to acquire around 5500 images with a GSD of 1 mm using a Sony alpha 5000 camera. Due to the building’s location, our flight was not approved by the city and we were forced to use a truck lift as our “aerial platform”. This, however, allowed us to tightly control the camera’s position to get the high level of detail. The image acquisition plan, as well as some of our calibration techniques, allowed us to meet the goals mentioned above.

We had to pull out all of our tricks on this project due to the accuracy requirements, the number of images, and file sizes that pushed our computer hardware to the limits. Pix4Dmapper was the choice software for this project due to its flexibility in allowing us to adjust any setting we needed.  Especially when it came time to merge all the smaller subprojects into the final model, the ability to use tie points and add calibration constraints was key to the project’s success.