please describe the most difficult components in the "structure from motion" problem in robotics.
In robotics, there are three key stages involved in solving the structure from motion (SfM) problem:
1. Feature detection and extraction - this involves finding high-contrast features such as corners or edges within a camera view to define points of interest for the SfM system
2. Bundle adjustment - a process that optimizes the relative poses of all images according to the geometry constraints imposed by the feature detections
3. Camera calibration - correcting errors introduced during the image capture process so that the images can be accurately aligned and reprojected into 3D space