Spotlights Projecting maps - possible in vray?

[sanya]

hello everyone,

Does Vray have this feature to load bitmaps into a spotlight to have a result like a regular slide projection? Maybe a plugin?
I am asking this because i want to get deeper into rendering to improve my previz techniques for stage lighting and set design. projection is very important in my work, so the renderer i choose should have this special feature.
All i know so far is that it can be done in 3Dmax, but i see no chance for me to find the time learning max...
Any pointers would be highly appreciated!

thanx in advance
s.

(hai thomthom, good to see you here! greeting from Berlin)

[thomthom]

Re: Spotlights Projecting maps - possible in vray?

Hi there!


There isn't any spot light in V-Ray. Only omni lights. And they can't be mapped with a texture. To make a spot you would have to model a cone around the spot.
As for the texture for your projectiong, I'm not 100% sure, but maybe a face at the end of the cone with a transparent texture map. I'll try to test this when I get some spare time. Unless someone else here at the forum comes up with a clever idea.

[sanya]

Re: Spotlights Projecting maps - possible in vray?

Thomthom,
Thank you for the reply and your helpfulness!
if a omni behind a transparent texture map can produce colored and focused projection, this is all that i would need.
If this is not possible, however, it would be a bit sad, cause i definately like the quality of vray renders a lot!
Anyway, thanks again, and let me know what you have found out...
sincerely
a.s.

[Jackson_cg]

Re: Spotlights Projecting maps - possible in vray?

I think it was Micha who originally came up with the "clever idea" for faking IES lights and "andeciuala" who mastered it for SU, but it still took me about 3 days of experimenting before I got satisfactory results for faking IES.

andeciuala's thread which covers the basics and has some excellent tranparency maps to start with is here:
http://asgvis.com/index.php?option=c...0&topic=3932.0

My test render


What I spent most of my time on was:

a) Editing transparency maps in PS for different effects.
b) Making six distinct recessed luminaires which could be dropped into the ceiling of any model.
c) Reducing poly count while also reducing light leaks.

The main trick to this method turned out to be using a 0,0,0 black material on all faces of the luminaire which couldn't be seen. The reflector doesn't actually focus any light, so it's just a 12 sided cone with white material applied to bounce as much light out as possible without creating artefacts/splotches (as a mirror material would). I also intersected some faces so rather than meeting perfectly with the ceiling they continued through it for 2mm (notice the inner edge of the luminaire extends slightly above the outer edge). These two tricks reduced light leaks enormously which can be a major problem when using high intensity omnis within very small geometry. This in turn allows you to keep your visopt settings pretty fast. For clarity the attached sections show a regular (but scaled down) VfSU omni light inside the luminaire, but this presents a problem: how do you get at the VfSU omni to edit it's settings? In my actual components I solved this problem by editing the geometry inside the VfSU omni component as the polyhedron geometry inside a VfSU omni component doesn't actually do anything other than give you something to see and grab onto in SU. I edited it so rather than the polyhedron I have an upside-down pyramid, with its point at the dead centre of the VfSU omni component. The reason for editing the standard VfSU omni polyhedron is that it allows you to easily select the VfSU omni from above the ceiling (as the "base" of the upside-down pyramid extends well above the reflector cone) for editing intensity, decay, etc, but none of the omni is visible below the ceiling which would make for an ugly SU model (ceiling with big omni balls all over it). I also added SU text to each VfSU omni stating what the intensity and decay was so that it's easy to keep track of settings. You can also then adjust the "focus" of each luminaire by moving this omni up (tighter spot) or down (wider flood).



You can load any square texture into the SU material slot for the tranparency map of the luminaires as it will be overidden by the effect of the VfSU omni shining through the VfSU transparency map, but I chose to use a simple one with a dark dot at the centre so in the SU model it looks vaguely like a spotlight reflector. I created 6 clones of this SU material, called IES Map 1, IES Map 2, etc for each distinct luminaire component and then (even though they have identical diffuse maps) loaded different fake IES maps in the VfSU tranparency slot. This way I have six different IES patterns for six different luminaire components which can all be edited simultaneously by editing their respective VfSU material transparency maps.

You can easily create coloured lights by adjusting the colour settings for your VfSU omnis and in theory you may be able to create multi-coloured light patterns by editing the transparency maps in PS (I'll have try that out). The only real limitation of these simple fake IES lights is that you can't focus the light at a certain distance like you can with a real reflector or lense.

Phew, was that everthing? Not sure how much sense that all made. After all my experimenting I was actually a little irritated to hear that true IES lights will be supported in the next VfSU version LOL.

[thomthom]

Re: Spotlights Projecting maps - possible in vray?

Good one Jackson. I'd forgotten about the fake IES method.

Only question now is, how well odes it work with colours? Alex wants to simulate a slideshow projector.

[Jackson_cg]

Re: Spotlights Projecting maps - possible in vray?

LOL, I plead guilty of not reading the whole post before replying, I just assumed from the topic title and replies that the question was simply about spotlight lighting patterns. In any case the principle is the same.

I remember Damien saying ages ago that V-Ray didn't like coloured transparency maps (maybe that was just regarding clipmapping), so I thought you had to use a refraction layer for this, but for projecting multicoloured light the same transparency map method works perfectly. I just dropped a square Swedish flag png into the transparency slot to replace my grayscale IES map and it came out fine first time. I don't think this particular effect will be that useful (unless I have a particularly patriotic client LOL), but it'd be nice to create very subtle refracted lighting effects or projections.

[thomthom]

Re: Spotlights Projecting maps - possible in vray?

That's great. Just tried it myself.

At first I tried with a face with a texture and just setting an even opacity to the texture. That didnt' produce any good results. But using the texture in the opacity slot works perfect.

My own test, just a omni inside a cube:

[Jackson_cg]

Re: Spotlights Projecting maps - possible in vray?

That looks great Thomas! It would be neat to project images onto large irregular surfaces, e.g. building facades in nightshots.

[thomthom]

Re: Spotlights Projecting maps - possible in vray?

That looks great Thomas! It would be neat to project images onto large irregular surfaces, e.g. building facades in nightshots.

Funny you should mention that. That's exactly what Alex does.

Check out these links:
http://www.paintmyhouse.de/
http://www.skudioptics.com/projekte

He did a project in Trondheim where I live. Projected artwork on to the old cathedral. Very cool.

[sanya]

Re: Spotlights Projecting maps - possible in vray?

Fantastic!

Jackson, Thomthom,
I see my own reflection in the glass of my monitor and it looks like the face of a lunatic - grinning from ear to ear. all smiles.
Thank you guys so much for all the effort to sort this out for me!
I already feel at home here, even before downloading the demo version! And that is exactly what I am going to do when I get some days off after my current project. Can't wait to check out opacity slots and greyscale IES maps (both patriotic and nonpatriotic ones
yeeha!
thanks again very much - see you around
alex

[sanya]

Re: Spotlights Projecting maps - possible in vray?

Thomthom,

Thanks for the credits man. For me the best thing about our show in Trondheim was to meet all you exeptionally openminded people.
This is anything but granted.

give thanks
a

[thomthom]

Re: Spotlights Projecting maps - possible in vray?

Did another test to predictably position the "projector".



Test scene:
http://download.thomthom.net/3d/sketchup/Projector.zip

[labuto]

Re: Spotlights Projecting maps - possible in vray?

That's great. Just tried it myself.

At first I tried with a face with a texture and just setting an even opacity to the texture. That didnt' produce any good results. But using the texture in the opacity slot works perfect.

My own test, just a omni inside a cube:

I found your solution very useful! however do you know how to do the exact same in 3DSMAX?
i tried a whole day to make it work...but it didnt...
thanks in advance!

[thomthom]

Re: Spotlights Projecting maps - possible in vray?

Doesn't max have the ability to assign bitmaps to lights?

[fpedrogo]

Re: Spotlights Projecting maps - possible in vray?

Doesn't max have the ability to assign bitmaps to lights?

Yes, it has.