Photogrammetry from your phone

    Today while doing some more research into photogrammetry I came across a youtube videom from channel School of Motion;

https://www.youtube.com/watch?v=ZIW4XU6Wm8Q&ab_channel=SchoolofMotion

    In this video Patrick Letourneau, a 3D artis and Photogrammatrist, explains and demonstrates how to achieve a reasonable 3D model scan with nothing but your phone and a program called Reality Capture that is free to download however exporting the model is priced on how detailed the end result is. 

    Patrick explains that flat lighting is the most important thing to consider when taking the photos as this can affect the information that is retained in the models texture and normal map when it comes to baking, so to always shoot anything outdoors on an overcast day to avoid noticeable shadows being cast from the sun, which would need to be cleaned up later down the pipeline. 

    He also added that using your phone's built in camera is usually not a good idea unless you can manually adjust settings such as ISO, Shutter speed and focus. If your phone isn't capable of this then there are apps available to download that can allow you to do this. 

    One thing I noted is that while taking the photos he wasn't completely precise with angles and distance from the object. Obviously Patrick is a professional at this and knows what he is doing, but it goes to show that to get started the basics are all you need to consider and the software can do a lot to correct mistakes. Patrick focused on taking as many photos as possible in a methodical approach, ensuring to capture as much detail as possible to give Reality Capture what it needs to work it's magic.

    Patrick then goes on to breakdown the workflow inside of Reality Capture, showing how simple it is to get from the raw photos to a fully realised 3D model, touching on things like retopology and smoothing out the mesh to reduce noise that was generated because of the camera quality.

    Of course he explains trying to do everything in a clean studio setup where you have a high resolution camera and control of the lighting is the best way to get near perfect results however, I was impressed at how far the quality of this model came along simply from using his phone and spending a short amount of time adjusting things within this software.

      Even within Reality Capture itself the model looks great and I was thinking of how long it would take me to model and texture this in a more traditional method such as using Maya or sculpting it in Zbrush and then texturing it in Substance. This would be days of work for someone who is much more proficient than me in modelling and probably would take me at least over a week if not longer to get it to this level of quality. However this was made in a matter of hours from taking the photos to importing them in and tweaking the outcome. It really does show the benefit photogrammetry can have on drastically reducing the time needed to be spent on certain high detailed models.

    Lastly Patrick takes the model into Cinema 4D and shows how to set it up for rendering out to a finished product, he also went on to compare the phone scan to a scan he did in his studio setup with his DSLR and pointed out the differences between the models in terms of lighting, detail and so on. Which yes side by side it is very easy to see a marginally increased difference between the two, however the phone scan could still very well hold up in any realistic gaming environment without too much scrutiny depending on the asset and how it is utilised in game.

    I would like to do my own similar study of the difference in quality between phone scanning and a studio scan setup, and while I know the results will differ the experimentation through practice will be key in my development, as well as offer further insight into the time it takes for both processes and the benefits/negatives of each.