Hi Alex--
I agree with several earlier responses that Agisoft may be an affordable, user-friendly approach for your needs. We just published a paper in the Bulletin of the Seismological Society of America (BSSA) of a detailed workflow and error analysis using Agisoft to construct 3D models (and 2D paper trench logs) of paleoseismic trench exposures. The paper will come out in October, but was posted online this week:
Nadine G. Reitman, Scott E. K. Bennett, Ryan D. Gold, Richard W. Briggs, and Christopher B. DuRoss, 2015, High‐Resolution Trench Photomosaics from Image‐Based Modeling: Workflow and Error Analysis, Bulletin of the Seismological Society of America, Vol. 105, No. 5, pp. –, October 2015, doi: 10.1785/0120150041
Paper: http://bssa.geoscienceworld.org/content/early/2015/08/26/0120150041.abstract?ssapaptoc
Esupp: http://www.seismosoc.org/publications/BSSA_html/bssa_105-5/2015041-esupp/index.html
As others have mentioned, you'll need ~50-60% photo overlap, and a minimum of 3 ground control points to reduce undesired warping in the model. Our paper provides analysis of the trade offs between increasing the number of ground control points and the resultant reduction in model error. It sounds like the scale of your cliff face exposure is similar to our paleoseismic trenches and our workflow could be easily applied to your photographs. Feel free to contact me if you decide to use Agisoft and have any questions about its implementation, or need a copy of the paper and detailed workflow (in the Electronic Supplement).
Cheers,
Scott
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Scott Bennett
Research Geologist
U.S. Geological Survey
Seattle Field Office
Affiliate Assistant Professor
University of Washington
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www.scottekbennett.com
profile.usgs.gov/sekbennett
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