Friday, May 1, 2015

Desktop SfM Background and Scale

It seems like I've been doing/helping out with a lot of "desktop" structure-from-motion modeling. Through various iterations and attempts to scale the final SfM point clouds, the Van Gogh scale has emerged. So, I thought I'd share it in the hope that others can get some use out of it.

The background image helps the SfM image matching algorithms do their thing, which is especially helpful when modelling smaller things or objects without a lot of surface texture of their own. It also gives a nice contrasting surface that represents the desktop (which can help with editing it out later on).

Download Here (Google Drive link)
     |_ VanGogh_scale.pdf  (PDF for printing)
     |_ VanGogh_scale.svg  (Inkscape scalable vector graphics for editing)
     |_ VanGogh_coord.csv  (comma-delimited coordinates)
     |_ VanGogh_coord.txt  (tab-delimited coordinates)

Creative Commons LicenseThis work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Be sure to set the PDF print options to "Actual Size" to ensure that the scale is 1:1.

The coordinates printed on top of each circle target are centimeter measurements, but in the VanGogh_coord files the values are in meters (20 cm = 0.20 m). All of the Z values are zero, assuming you're on a level surface. The numbering scheme in the VanGogh_coord files is columnar (top to bottom, left to right).

Sparse point cloud of my hand from Agisoft Photoscan
Dense point cloud from Agisoft Photoscan

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