OTOY Forums

Hi there.
I'm facing an issue which I don't think is a bug, but I don't know how to deal with it.
I'm using a very small octane light with a projection map to simulate a "video projector".
It works well, but now I want the projected light to reflect on a small mirror to send the upper half of the projection to the ground :


...but it needs to much samples to actually "reflect" the light :


Result after 200 000 samples :


It also seems that the reflection is "handled" by the "caustic" algorithm ... (don't know how to tell it). The "caustic blur" parameter of the render engine turns the reflection "blurry" (of course!)

Same render at 200 000 samples with "Caustic Blur" set to 0.05 :


Is there any way to optimize the caustic reflection, or to use a more "direct reflection" of the projected octane light ?
Thank you.
Carlos.

Hi cmatias,
it's a bit of real jam. Theoretically this is possible, but you should have a source with a very small surface with a super projective power; an example of what you would like to achieve is something like a laser.
What you project is basically a caustic, so you will need a lot of samples to clean up all the noise you will have.
PMC kernel is probably the right choice, but the question is: does it make sense? I would think to have a fake projector on stage.
Regards
Paride

Thank you Paride for this answer.

Your question “does it make sense?”, makes sense!

The main activity of my company is to build museum exhibitions and I’m in charge of everything related to dynamic screens, video projections and interactivity.

The brain teaser part of it, is where and how to place video-projectors… I’m usually taking hours to find the right video-projector, at the right place to get the right picture.

I’ve recently started to develop a small 3ds Max plugin to simulate every video-projectors we can get on the actual market.
I’m trying to include every parameter of each projector to get a geometric representation of the projection plane (a solid tetrahedron visible in the 3ds max viewport and renders).


I’ve been able to get the “links” between a very small OctaneLight and its distribution map properties (UV transform & Projection map) to simulate the “video projection”, but there are some tricky cases with very small space where I can achieve the goal using mirrors.

It’s very nice and comfortable to move those Octane lights around in realtime to see if the projector will fit the available space, and I would like to do it with mirrors.

Sorry for my English speaking level, I hope you understand what I mean.
Regards.
Carlos

by rendering technique point of view,
why not just fake a mirrored projector which location is easily be calculated out (and the region to project by your plugin ), let it to project on the ground, that will be much easier than testing the render engine's function of simulating the ray's physical behavier...
guess the future PPM kernal which is for caustic may make your experiment true...

jimho wrote:by rendering technique point of view,
why not just fake a mirrored projector which location is easily be calculated out

Unfortunately not as easy as you think...