Experimenting with photogrammetry at home

Jan 21, 2019

Dušan Ković

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Experimenting with photogrammetry at home

Jan 21, 2019

Dušan Ković

We love it when our readers get in touch with us to share their stories. This article was contributed to DIYP by a member of our community. If you would like to contribute an article, please contact us here.

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This is going to be a long one…

Photogrammetry is my hobby for the last couple of years. My first try was a small wooden Piggy from four or five years ago. That was done with a mobile phone (Nexus 4) without any knowledge of proper lighting, manual control of the camera, balancing photos, etc. The scanned result was pretty bad, but I learned a lot from it. After that, I bought a Canon EOS700D with kit lens and started to learn more about the proper way to take photos, how to correct them and how to work on the scanned geometry. Results got a lot better with the proper equipment

But this is still the realm of simple shapes and hard surface objects. My goal was to scan a human face. And that is where my lack of knowledge and equipment started to surface even more. I started to experiment with my wife’s head (girlfriend back then). The first try was pretty unsuccessful – bad mesh full of noise, with textures full of lighting information.

Then, I went back to googling about what is the best way to take photos for photogrammetry. After that I did two more photo sessions, but this time in the cloudy weather with more diffuse and uniform lighting. Results were better, but still not what I’ve hoped for.

Still, not satisfied with the results, I went back to googling how to improve the results, and I figured out that hair was creating a problem in the alignment. So I got a thin cap, I’m guessing it was used for wigs, to hide real hair. Another photo session… At this point, she was starting to get annoyed for being my “guinea pig”.

Again, a step in the right direction, better than any version before, but still not good. But I decided to try to “fix it in post”. Went to Zbrush, cleaned the model, did an ok retopology, texture transfer, basic shading… Aaaaand… Super uncanny results : D

I figured out that I don’t have almost any knowledge of human skin shading. Also, I have a lot of specular in my base color showing in the render… Back to googling… After a while, I found out about CPL filters. Bought one, another photo-session with Ivana… At this point, I couldn’t figure out if she is hating me more because of another photo – session or because she has to wear silly wig cap outside on the street (I didn’t have lights so I used overcast sky for lighting).

CPL helped out a lot and I had cleaner photos, also I did solid mesh cleanup in zbrush but…

Better, but still uncanny… Lack of shading skills did its work. At this moment I wanted to take a break from the project. I had to learn more about the scanning process, photo editing, shading, etc, etc…

Fast forward!

3 years passed since I started the project. In the meantime I got proper lights, new camera (Sony a7mII) and Zeiss lenses, macro tubes, CPLs, Xrite Color Checker, light tent, did a lot of scans and learned a lot. So here is the new setup:

With this I’ve managed to get pretty solid results.

Then it was time to try the human scanning again, this time with better setup and knowledge. : D

Notice the guitar stand tied to the back of the chair to serve as the head stabilizer. : D

I’ve managed to persuade her to take another photo-session. :D Also I had a friend of mine rotate her on the chair. And I finally managed to get proper results. Evenly lit photos and solid alignment. Again, new cleanup, retopo, texture transfer, and baking, etc… The image below is cleaned up a bit but totally usable.

Just a uniform spec pass to show skin detail.

And with some new knowledge of texture painting, shading, etc… Rendered on Arnold GPU.

It is finally starting to take shape… That’s why I am writing this, just to share the project that I’ve been working on (with breaks) since 2015. Also, I never published any scanned assets anywhere (aside of two Instagram stories).

This latest iteration is from the last couple of months. It still requires a lot of work – missing a couple of maps, it is without any hair (still have to learn to create hair), etc… But it has the potential to look great at the end. I hope I will manage to publish finished project later this year.

This was a long post, thanks to anyone who managed to get to the end : )

About the Author

Dušan Ković is a CG Artist from Novi Sad, Serbia. He holds a bachelor degree in graphic engineering and design and he’s interested in all areas of computer graphics, with his favorite areas being photo-realistic texture painting, lighting, lookdev, and rendering. He’s also a fan of analog and digital photography. You can see more of Dušan’s work on his website, Instagram, YouTube and Vimeo. This article was also published here and shared with permission.

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One response to “Experimenting with photogrammetry at home”

  1. Gvido Mūrnieks Avatar
    Gvido Mūrnieks

    Quite cool! I too have played with photogrammetry, “back in da day” :D
    What software did you use in your workflow? Did you re-made the scanned mesh into something useful, like remodel the face with proper mesh flow and laid out UVWs?