Photogrammetry and Structure from Motion concepts

Topic 2: Structure from Motion

Outline

• Remote sensing and photogrammetry: what each contributes to UAS mapping
• Why a photograph is not a map: perspective, relief displacement, orthorectification
• Overlap, stereoscopic coverage, and tie points
• Principles of Structure from Motion and bundle adjustment
• Anchoring the model: geotags, ground control points, checkpoints, RTK/PPK

Lecture

• Lecture Slides: Photogrammetry and Structure from Motion Concepts

Supplemental materials

• Structure from Motion demo: interactive visualization of a UAS camera tracking ground points along a flight path
• Aerial Photogrammetry Concepts (2016 slides): more on the history of aerial mapping
• Reconstruction of Palmyra from tourist photos (Wahbeh et al. 2016)
• Reconstruction of popular monuments from crowdsourced photos (Hartmann et al. 2016)
• Open Heritage: 3D models of iconic locations (CyArk and Google Arts & Culture)
• Introduction to Structure from Motion Photogrammetry, OpenTopography short course at GSA 2021 (OpenTopography 2021)
• Multi-View Stereo: A Tutorial, the standard reference on dense matching (Furukawa and Hernández 2015)

Assignment

• Assignment 2A: 3D reconstruction from multiple photos: photograph an object, build a 3D model from the overlapping images, and report how the number and orientation of photos, lighting, and the object itself affected the reconstruction. See the assignment page for the report requirements, submission instructions, and due date.

References

Furukawa, Yasutaka, and Carlos Hernández. 2015. “Multi-View Stereo: A Tutorial.” Foundations and Trends in Computer Graphics and Vision 9 (1-2): 1–148. https://doi.org/10.1561/0600000052.

Hartmann, W., M. Havlena, and K. Schindler. 2016. “Towards Complete, Geo-Referenced 3D Models from Crowd-Sourced Amateur Images.” ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences III-3: 51–58. https://doi.org/10.5194/isprs-annals-III-3-51-2016.

OpenTopography. 2021. Introduction to Structure from Motion Photogrammetry. Geological Society of America 2021 short course, lectures and demos. https://opentopography.org/workshops/GSA2021.

Wahbeh, W., S. Nebiker, and G. Fangi. 2016. “Combining Public Domain and Professional Panoramic Imagery for the Accurate and Dense 3D Reconstruction of the Destroyed Bel Temple in Palmyra.” ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences III-5: 81–88. https://doi.org/10.5194/isprs-annals-III-5-81-2016.