What are "oversamples" in 3D rendering?


(rwv01) #1

What does it mean when an image is rendered with
a certain number of oversamples?

Is this something to do with ray-tracing?


(shibbydude) #2

I don’t mean to be mean but oversampling has nothing to do with raytracing. Blender does not raytrace. It is not a raytracer it is a scanline renderer. Overampling is the number of times the edges in the rendering are averaged (sampled) together to make more smooth edges. If oversampling is 8 then the rendering will check the edges eight times? I don’t know if that is how it works but that is what oversampling is.


(theeth) #3

it means that there is X sample of the image being taken, and that those samples will be blended together for a smoother lines. Basicly, it removes the jaggies.

Martin


(harkyman) #4

Wait a minute - are you saying Blender uses a jittered sampler for anti-aliasing? I thought the standard AA method (from whence comes the term “oversampling”) was to actually render edges at a higher resolution (2x2 or 4x4 etc. grid for each pixel) and then average them resultant matrix together to give you a nice single pixel color. Am I wrong?


(theeth) #5

Harkyman: I’m not sure anymore, you’re probably right.

Martin


(rwv01) #6

Yes I know. Sorry, should’ve asked that another way, but your answer makes it unnecessary. Thanks.

So then oversampling is how the edges are averaged together during anti-aliasing?


(shibbydude) #7

Yeah, blender averages pixels to get a median color-per-pixel. So 2x2 and 4x4 and so on (if your computer is fast enough :))


(meestaplu) #8

Oversampling is clearly relevant to Blender - but I don’t think rwv01 asked about Blender specifically.

This site:
http://www-viz.tamu.edu/students/gary/617presentation/
provides an excellent overview of various techniques of oversampling, or antialiasing.

For everyone who answered specifically about Blender, keep talking! :smiley: I think everyone would love to know how Blender does oversampling - if we knew, we maybe could use the feature more effectively.