Canyon Scene Reconstruction: Ideal Footage for Scene Reconstruction

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Instructor Rick Barrett

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Learn 7 key factors to consider when choosing or shooting footage for Scene Reconstruction

In this video, you’ll learn about key footage characteristics that affect the quality of scene reconstruction. Using examples from ArtBeats footage library, we’ll explore 7 key factors that you should keep in mind when choosing or shooting footage for Scene Reconstruction:


  • Good Parallax
  • Multiple Angles
  • Minimal Blur
  • Minimal Lens Distortion
  • Even Lighting
  • Limited Reflections
  • No movement within the frame


Footage for this tutorial series is provided by permission from ArtBeats via the Files link above. Visit Artbeats.com to learn more about PremiumPass and browse the complete library of 14,000 clips.

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Transcript

With scene reconstruction, we'll be generating 3D geometry from video footage. So obviously, the first thing that we'll need is a piece of video footage. I know that you don't usually have the luxury of choosing your footage, but because this is a tutorial, I do. And Artbeats was kind enough to provide me with a premium pass, so that I could choose from the 14,000 clips in their library. And I am going to use this library to show you some of the things that you should consider when choosing or shooting your scene reconstruction footage. And, the first thing to keep in mind is that you need a lot of parallax. You need objects both in the foreground and the background that are moving in different speeds and that's sort of the fundamental of how motion tracking works. And because we're trying to reconstruct geometry, we actually need to see the object that you're reconstructing from multiple angles so that we can construct as much of that geometry as possible. For that reason, I found that city aerials work pretty well. You just want to avoid shots that have a lot of motion blur or depth blur, because any kind of blurring is going to blur the texture detail and that's essential for the scene reconstruction engine to be able to determine the shape of the surface. Also, you want to avoid extreme lens distortion, because distorted footage is going to lead to distorted objects. Another thing you want to avoid is strong shadows, because again, that texture detail is going to be lost in those shaded areas. So, try to avoid footage like this that was shot on bright sunny days. You want footage that's shot on overcast cloudy days, you can always replace the sky later. Also, again, cities work really well. This is a good example of parallax and lots of objects at various depths, but you want to avoid footage that has strong reflections like this. This kind of a reflection is obviously reflecting an object that's in a different physical 3D space than the reflection itself, and so that's going to trick the scene reconstruction engine and it's not going to be able to properly reconstruct that area. You can get away with a little bit of reflection as long as it's broken up like it is in this building here. That might be trackable, but you definitely want to avoid a building like this that's purely reflective. Now also, you want to avoid clips with a lot of motion in them, because that motion is going to trick the engine. It's assuming that everything in the clip is stationary, basically. And you can mask around some of the motion when you're creating your trackers, but a clip like this would be very hard to reconstruct because of these crashing waves. So, from all of the clips in the Artbeats library, I chose this one of a canyon. You can see it has nice even lighting, not a lot of shadows, and also there's great movement, but the movement is slow enough that there's not a ton of blur. So, this is what we're going to be using for reconstructing and Artbeats also was kind enough to allow me to distribute this clip at 720p resolution with this tutorial so that you could follow along. So whether you need stock footage for your scene reconstruction project or any other type of need, I recommend checking out what Artbeats has to offer. So in the next tutorial, we'll pull this footage into Cinema 4D and track the camera, which is the first step in generating 3D geometry from our video footage.
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