My Small Object Photogrammetry setup

I thought I’d write a quick post about my photogrammetry set-up for small objects, because I’ve been doing a lot recently, and as a result I’ve spent some time optimizing my workflow.

The long and the short of it is that it looks like this:

Photog4.jpg

I’ve got a small light box from Amazon, which includes soft background and LED lighting. (Affiliate link: https://amzn.to/2wn4mra).

My Sony Nex-6 with 16-55mm lens, fully zoomed and manually focused, supported by a normal camera tripod.

Then I’ve got my Samsung note 8, upside down balanced using a flip case.  Being upside down, I’m able to get the lens really close to the table (wine helps with photogrammetry):

Photog1.jpg

This gives this kind of image:

Photog3.jpg

Which, as you can see is nice and low, while the Nex-6 is taking photos from a higher level.

Now, the beauty of this setup: The Note 8 (and likely some other phone cameras) can be activated by voice!  So I can press the shutter button on the Nex-6, and say ‘Cheese’ or ‘Snap’ and both cameras will take a photo.  I then reach in, rotate the object by a small amount, and repeat.

I try and take about 40 pictures per revolution of the object, but having both cameras firing simultaneously means I can get 80 photos in two circles at different heights, in just a minute or two.

A successful reconstruction in AliceVision Meshroom looks like this:

meshroomcircle.png

You can see the two circles, the smaller lower one from the phone camera, and the larger higher circle from the DSLR, both providing full coverage.

Hopefully that’s of use for people who want to speed up data collection without resorting to expensive camera synchronization (or pushing lots of shutter buttons), relying on just a camera and a phone.

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6 thoughts on “My Small Object Photogrammetry setup

  1. Dear Sir,

    Excellent as always. I have read many of your posts and have found valuable advice.

    I was wondering whether you have considered using hacked cameras? Wen I built my 8mm film scanner using Arduino, I found the CHDK, Caon Hack Development Kit, and that enables me to shoot thousands of pictures of 8mm frames without any manual interaction. Details at http://www.sabulo.com/sb/8mm-film/the-8mm-film-scanner-telecine-project-part-2/

    I am also building a servo motor operated turntable for scanning purposes, which may be of interest you once I get the parts printed and the Arduino robot coded.

  2. Have you considered building a custom camera rig? With a Raspberry Pi and an expansion bus you could run several cameras simultaneously for ~$200 total, and I imagine it could also be used to control a servo operated turntable simultaneously and automatically trigger the cameras at specified intervals of rotation. Resolution would be limited to 8MP; since I’m new to SfM and haven’t really brushed up on literature I’m not sure how models scale with image resolution, or if the increased volume of images would compensate for the loss of data per image (therefore I’m also not sure whether or not this would be a justifiable project from a cost perspective, since $200 is enough for another decent standalone camera). I think subject sizing would also be an issue, since most Pi compatible cameras have cables that are around 6 inches long, so at most you could get a 12-inch spread without buying additional cabling.

    The Pi definitely isn’t capable of running any of the processing software, but it should be able to handle image capture at a rate of about 1 image per second from each camera. I’d like to hear what you think about the potential here (or lack thereof).

    1. I have indeed. I have a set-up with raspberry pi for motion capture (see here: https://figshare.com/articles/Reconstructing_moving_morphology_using_RaspberryPi_PiROMM_Range_of_motion_in_ostrich_cervical_vertebrae_at_progressive_stages_of_dissection/5155462), but I think for photogrammetry the cameras just aren’t good enough (at least the v1 and v2 I’ve tried). I’d like to get a turntable plus camera trigger set up (probably controlled by a pi) but I haven’t had time to do so yet sadly.

  3. Hello,

    I would like to share a short clip of my HD webcam / Arduino rig. i am using SkyStudio Pro to do the capturing at 3 sec intervals, then do the mesh in Autodesk’s Recap at the moment. Due to Dr Falkingham’s excellent blog, I have also got academic licensing for the Zephyr softweare, which looks promising.

    I will write up a blog on how I made this system in the near future.

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