Maxwell Render | Official public forum

... is it possible to simulate a projector throwing a movie on a mirrored shape and seeing the bounced projection where it ends at the wall ?



How would I do that ? Can I use a Camera Projection in SI for that ?

Regards,
Frank

I have made a test with an emitter, a mirror and a wall, but wasn'y getting any hard reflection on the wall yet. Any idea how this is to be achieved ?





here I hid the mirror to see what the difference is

I remember someone in the forum tried to do it long ago:

http://www.maxwellrender.com/forum/view ... 088#175088

and

http://www.maxwellrender.com/forum/view ... r&start=15

Sadly all the images are gone, but maybe you can dig some information there or try to ask the publisher by mail. It's been a long time since his last post here.

I would love to see that but I looks like his whole account has turned into an advert

Personally I have done similar things but without any colour,
For accuracy it is important to use a very small light source, you can mask this using planes and an object properties tag to hide the object (in c4d), you may be able to use a plane closer to the reflected surface with the colour information there.
Alternatively you can fake it using various plane emitters and plane 'gobos' using object properties.
I would love to see any alternative solutions though

From one of those two links I posted:

So did you map an image to glass material and then project light through it?

I used a glassmaterial from wizzard, added the image at both Reflectance (0) and Transmittance. Thats it. But the colors are to sharp now, so maybe it needs some finetuning.

Maybe that can give you a hint.

Fernando Tella wrote:From one of those two links I posted:

So did you map an image to glass material and then project light through it?

I used a glassmaterial from wizzard, added the image at both Reflectance (0) and Transmittance. Thats it. But the colors are to sharp now, so maybe it needs some finetuning.

Maybe that can give you a hint.

So I guess combine that technique with the one I described...
remember that the reflected light will also pick up on the 'invisible to camera' coloured glass plane so it will have to be positioned carefully to avoid obstructing the reflection

I tried to build this projector but didn't get a picture on the wall yet ...

Sadly, I don't think your projector would work in real life either...
To avoid having to play around with lenses which I imagine would slow things down alot simple use a small light source (ies or sphere with emitter applied), Then create an enclosure made of planes in a sort of pyramid shape with an open bottom, at the open bottom place a cuboid with the glass material applied (As if it were a large slide)
you can then hide all of these objects from camera but you must remember that the objects will still obstruct light...

Yep, I think the small light source is the key to get focus (the light bulbs of the projectors are usually quite small too). I think a plane would do: remember that the less triangles the faster.

Fernando Tella wrote:Yep, I think the small light source is the key to get focus (the light bulbs of the projectors are usually quite small too). I think a plane would do: remember that the less triangles the faster.

touche

a solution

Hi Bograt,
true, the projector is not the greates . Thx for example. Trying to understand it to replicate. Is the emitter hidden ? Also, is the test setup bouncing the light back from the mirror to the surface in the air ? Pls let me know how I can redo the same setup.

Regards,
Frank

Hi Polynurb, just seeing your solution link, thx for the detailed explanation. will try setup the same now.

My goal is to be able to simulate a reflector and / or lens, that distributes a projected movie onto shapes like a panorama cylinder or others. So that the movie is bent exactly the way as needed.

There is a laser projector coming up that I want to simulate the result with . As I read from another source some times ago, the laser has the advantage of staying focused also with differing distances to the projector-wall (screen). The question is if simulating that case is possible and how that can be achieved accurately.

In Softimage ICE it is possible to create a particle raytracer, which probably can be used to exactly simulate the result of a bent reflector and thus to design it that way needed :

the example starts at time code 5:18.

I will send you the scene if you like, Do you have c4d?


sorry for the bad writing, my mouse if running out of battery