This example demonstrates bundle adjustment of camera extrinsics and intrinsics, as well as 3D landmark positions, for a Structure-from-Motion problem. The example isn’t particularly optimized for performance, but demonstrates the simplest way to set this up with SymForce.
We use the Bundle-Adjustment-in-the-Large dataset, as described here: https://grail.cs.washington.edu/projects/bal/
Feature correspondences have already been selected, and we’re given initial guesses for all of the variables; our only task is to perform bundle adjustment.
The camera model is a simple polynomial model, and each image is assumed to be captured by a different camera with its own intrinsics.
Ceres and GTSAM also have reference implementations for this dataset, see here for Ceres and here for GTSAM.
Script to download the dataset files into the
./data folder, run this first if you’d like to run the example
Defines the symbolic residual function for the reprojection error factor, and a function to generate the symbolic factor into C++. The
generate function is called by
symforce/test/symforce_examples_bundle_adjustment_in_the_large_codegen_test.py to generate everything in the
This is the C++ file that actually runs the optimization. It loads a dataset, builds a factor graph, and performs bundle adjustment. See the comments there for more information.