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Comment by shurcooL | Hacker News Reader

It's simple conceptually: I just draw a quad with non-zero exposure time.

For each pixel, I calculate how much exposure it receives during the last 1/60th of a second (assuming it runs at 60 FPS). So, if a pixel is backed by the triangle for 100%, it gets the full colour. If it's only 24% of the time, then it's 24% of the full colour, etc.

That's what happens conceptually. In order for it to run faster, I have to optimize the solution and basically calculate the same result, but by drawing some triangles and calculating some distances... It's hard to explain, but it's nothing more than an optimization.

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You can make it look even better by adding support for shutter (in)efficiency: http://www.dctsystems.co.uk/Text/ShutterPresentation.pdf resp. http://www.dctsystems.co.uk/Text/shutter.pdf

This is very interesting. I'm very curious how this relates to the human eye.

I remember playing around with adjusting something similar to this, but it was mostly to compensate for how monitors display images.

Shutters with an efficiency between 75% and 50% just look more natural, from my experience.

The stuff proposed in this papers made it into blockbuster VFX production renderers ca. 2005 (3Delight) and 2007 (Pixar's PhotorRealistic RenderMan).

There is no information available on what full CG features use this. However, when you look at a still frame that exhibits heavy motion blur in isolation, you can usually tell right away if a perfect of imperfect shutter model was used. The latter looks smoother/more natural.

As far as VFX in live action films go: it makes sense to match the virtual shutter to the one of the camera that was used to shoot the footage the VFX need to be integrated with.

The high end offline rendering plug-in, my company produces, has a setting for this. The default we use (and that most of our customers leave untouched, I believe) is 75% shutter efficiency.

Ohh, I see! Thanks :)

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