A tour of mrcal

mrcal is a photogrammetry toolkit that provides improved methods for making and using camera models (calibration, tracking, mapping, etc). Currently the focus is on calibration and uncertainty propagation, but more methods will be added with time.

The best way to convey a sense of the capabilities is to demonstrate some real-world usage scenarios. So let's go through a full calibration sequence starting with chessboard images, and eventually finishing with stereo processing. This page is a high-level overview; for more details, please see the main documentation.

All images have been gathered with a Nikon D750 SLR. I want to stress-test the system, so I'm using the widest lens I can find: a Samyang 12mm F2.8 fisheye lens. This lens has a ~ 180deg field of view corner to corner, and about 150deg field of view horizontally.

In these demos I'm using only one camera, so I'm going to run a monocular calibration to compute the intrinsics (the lens parameters). mrcal is fully able to calibrate any N cameras at a time, I'm just using the one camera here.

The tour is split over a number of pages:

  1. We gather calibration images, and perform some initial calibrations
  2. We compare the calibrated models
  3. We compute the projection uncertainties of the models
  4. We discuss the effect of range in differencing and uncertainty computations
  5. We find the best chessboard-dancing technique
  6. We use the models for stereo processing
  7. We use the models for triangulation