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  • I am not a professional photographer, so I ask for your indulgence in that some basics may not be obvious to me.
  • I am in the early stages of planning a scientific study on a moose (Alces alces) population.
  • One of the goals is to develop mathematical models of their scat.
  • In order to fit various mathematical models, I want 3D mesh data.
  • In order to obtain 3D mesh data of moose scat, I want to reconstruct them from images.
  • In order to reconstruct 3d meshes from images, I would like consistent images of each piece of scat from multiple angles.
  • Three of the more specific properties I want to be consistent are the lighting, colour balance, and resolution.
  • In order to reconstruct a closed mesh as an estimate of a scat pellet's surface, I need to photograph the whole surface.
  • While many scat pellets are convex, or even close to an ellipsoid in the nicer cases, we cannot rely on the scat being convex in all cases.
  • I own a rebel t3i DSLR.
  • I own a tripod.

I am thinking that I need some lights to keep the light intensity and colour consistent, although I do not know what else I should require for spectral properties. I have also thought that some sort of rotating platform with marked angles might help me take consistent images of most of a pellet's surface, but I have not worked out how to position the pellet without changing it when the pellet may not balance nicely.

I have read that it is desirable to have as low of an ISO as possible, which is a level of sensor sensitivity that can pick up less intense light but at the price of more noise. This is because the noise can create artifacts in the 3D reconstruction. So I think I need a brightly-lit setup so that I can set the ISO as low as I can (ISO ~100).

So my two problems seem to be:

  • reliable lighting
  • reliable positioning

How do I overcome these photography challenges so I can move onto doing some poopy math and science?

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    \$\begingroup\$ Far from my area of expertise, but I'm thinking you might get a better head start with one of the newer iPhones with built-in Lidar. They can already build 3D models just by moving the phone around the object, hand-held. \$\endgroup\$
    – Tetsujin
    Apr 19, 2022 at 7:09
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    \$\begingroup\$ Are you imaging the scat in the field at the various places you find it, or is it being collected and transported to you and being photographed in the same place for all of the samples? If the latter, please describe the environmental conditions (what type of indoor or outdoor structure, what kinds of ambient light sources, etc.) where the images will be taken. \$\endgroup\$
    – Michael C
    Apr 19, 2022 at 7:33
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    \$\begingroup\$ @Tetsujin I have used Lidar scans in forestry work in the past to get a higher-resolution topographic model. That is definitely something I will keep in mind when considering my next phone. Thanks for the suggestion. \$\endgroup\$
    – Galen
    Apr 19, 2022 at 15:23
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    \$\begingroup\$ @MichaelC I am collecting the scat and returning it to my lab bench, where there is LED lights and natural window light. I intend to use a windowless room for the photography to have better control over the light, or build a box to put the specimens within. Either way, I think I should purchase some lights. Thanks for the clarifying question. \$\endgroup\$
    – Galen
    Apr 19, 2022 at 15:28
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    \$\begingroup\$ Look in to photogrammetry which gives you a 3D model from a series of photographs. You don't need consistent positioning. A small turn table (lazy susan) can be made from a sealed bearing. A light tent with some work lights, as found in hardware stores, with 1600 lumen LED bulbs @ 5000°K should work for lighting. Use a calibrated gray card or Macbeth color chart for color correction. \$\endgroup\$
    – qrk
    Apr 19, 2022 at 16:03

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