Well, this is an interesting topic, but not for a short reply. I recently submitted a paper to Journal of Archaeological Science, making a review of the available affordable solutions for 3D recording and modeling at low and high optical magnification in the field of use-wear studies, but one of the reviewers, who is certainly preparing a paper on the same topic, stated that "There is no real new approach in this paper, no new experimental data, no new understanding of micro-wear data". As said Pierre Bourdieux, the French sociologist, science is a combat sport...
According to my experience with petroglyphs, bone and lithic tools, photogrammetry can works up to ~ 1.5:1 magnifcation (= macro objective with a short extension ring), but for helping Photoscan, which does an incredible work, it is better to reduce the resolution of the image (from 10Mp to 3Mp in my tests). At higher magnification, the depth of field is not sufficient for making the work comfortable: too many shots for carefully covering the whole volume or surface and then for processing. When depth of field is missing, the best solution, which is involved in all the low and high power microscopes allowing 3D recording (except the Leica IC3D module), including the confocal microscope, is focal plane merging, commonly called image stacking. In the intermediate magnification range, when depth of field is no longer sufficient for photogrammetry but still a bit high for getting a good vertical resolution (= enough steps), the solution is to combine the both principles. I already got nice results doing this, but not sure that the geometrical proportions are preserved.
The most complete and flexible software for image stacking is Helicon Focus (which includes Helicon Remote and a 3D viewer). However, its main function is not to provide 3D models. This is the reason why they are made in low resolution for being usable with any computer. Nonetheless, beside the light obj file, it is possible to save the depth map at full resolution. Such depth map can be processed by Interactive 3D Surface Plot, a plugin of ImageJ for getting 3D view, but no other way than screen shot for saving the result. As part of a research project entitled “Trac?ologie tridimentionnelle” (
http://lascarbx.labex-univ-bordeaux.fr/Les-actions-de-recherche-en-cours/Traceologie-tridimensionnelle-T3D,i634.html - sorry, in French...), funded by Lascarbx, the lab Archeovison has made two Meshlab plugins for modeling and calibrating the depth maps from Helicon Focus. These plugins will be available for free within a few months. Here attached an example at 200x magnification as seen in Meshlab (use wear on the edge of a Mousterian scraper).
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