Dumb question from a power user

[Speedster]

My mom used to say, "there are no dumb questions, only dumb answers"!  So here's my dumb question from a six-year KeyShooter-

Does KeyShot render only that which is seen on the screen?  Or does it also render hidden parts, like stuff that's inside a building, or perhaps inside a motor housing, but cannot be seen?  Does it render that which might be "off the screen"?

I ask, because hiding hidden items might speed up rendering time.  I run into time issues even on 32 cores.

Bill G

[edwardo]

If it makes you feel less 'stupid', I have wondered the exact same thing. In doing a few interior shots of furniture a while back i was casting shadows and bouncing light back into a scene with objects that were out of frame, so I guess keyshot must do its calculations including objects that are not seen. My curiosity concerned objects that were out of frame of the camera, whereas you seem to be asking about geometry that may be completely engulfed by bigger (opaque) geometry.

Sorry, not answering your question, just saying I've wondered the same thing. I have always hidden internal parts when rendering the outer casing (as long as it is opaque) on the assumption that it might speed things up. I guess a couple of quick test renderings, one with internal parts 'visible' and one with them hidden, might answer that question.

Heres a stupid question... If I eat myself, will I become twice as fat or disappear completely?

[Speedster]

And why does hot water running out of the tap sound different than cold water?

And why do we always sneeze twice?

And why, if you snore so loudly that you peel paint off walls, why don't we wake ourselves up?  Now, I've actually asked this question of many of my medical clients, and they have no idea!

And why does KeyShot 5 crash at the end of every large rendering?  And why, only when we look at the product of 3 hours rendering, do we then see a glaring screw-up???

Been KeyShooting to long- getting flaky!

Bill G

[Despot]

Hey Guys,

I would say that any geometry that is outside of the Field of View of the camera is disregarded by the render algorithm. This is probably done through Frustum Culling.  KS also might have an optimised scene description layer that passes information to the rendering algorithm. I'm not sure what happens if off-screen geometry is contributing to the final render through shadows, reflections and refractions though...

J

[Despot]

Heres a stupid question... If I eat myself, will I become twice as fat or disappear completely?

Hey Ed, surely things aren't that bad in Glasgow that you're resorting to self-cannibalism...

Here's a link that you guys might find interesting...

https://www.youtube.com/watch?v=IyUgHPs86XM

[edwardo]

Hey Ed, surely things aren't that bad in Glasgow that you're resorting to self-cannibalism...

lol, no, despite some strange times lately things seem mostly back to normal, so no cannibalism - back to a staple diet of chips and kebabs and lager and lard, all deep fried and battered 

That link looks good - will have a thorough look through it later. Thanks for posting it

Cheers
Ed

[Despot]

Lol, good to hear Ed...

Just watched that, very informative... reinforcing technical stuff I learnt years ago. At the end a beardy weirdy guy asks a question about Photon Mapping and specifically mentions Henrik Wann Jensen, wondering if said guy works for Luxion ?

J

[Speedster]

Frustum Culling

I knew this guy back in college! Or perhaps my memory is fading, and it was a village North of London!  Likely the latter.
Bill G

[soren]

KeyShot is a ray tracer and is computing a physically accurate image based on the geometry and lights in the scene and as such it always uses all the geometry present. However, we use very advanced algorithms and are quite clever about not using any geometry which does not affect the lighting in the final image.

As an example, try importing a high poly model and note that frame rate or render time in a sample scene. Then do the same but where you put the model inside a cube. You will notice that the frame rate will increase significantly (render time drops). I just did a test with a 15 million polygon model with complex materials and put it in a box: the frame rate went from 30 fps to 250 fps.

That being said, if the geometry is there it will consume memory and possibly also increase render time, but often not by much, but it depends on the specific scene. In any case, just try to render a low quality small resolution image with the object and without the objects (or hide them) and see if there is a significant difference. If the difference is on the order of a few percent I would not bother to worry about it.

But keep in mind that, unless the geometry is completely hidden, it actually does affect the lighting in the scene and therefore the final image. Light bounces around a lot.

P.S: Speedster, I think the hot water sounds differently because hot water has a slightly lower density than cold, but that is just a guess.

/Søren