What, if any, UVMap template does a point light use?

I have some point lights set up, with some procedurals to add colo(u)r to the light, which projects nicely out from the light itself (as you would expect).  What I would like to do it use an image map to project a variety of things, flames, caustics and all manner of stuff.

If any one has a clue as to the UVMap Template for a point light, or even a spotlight, I would me most grateful.

John.

Point lights use a UV template?  I was under the impression that they don't.

Tis an assumption, since it will take and project a procedural texture, I would think that it has some sort of uv information included.

Hopefully :)

John

when texmap is applied to poser lite diff channel, it causes posersurfaces illum. by lite to exhibit perspective mapping according to the distance and orientation of lite.  analogous to the "perspective UVs" function in poser (camera mapping).  i.e., lite is projecting  map onto  posersurface.  intent is to map lite to produce a gel effect, but result is to cause posersurfaces to have multiplied perspective texture.  like slide projectors they useta put kodachromes in, before film went extinct.

hence a point lite with texmap becomes a 360 deg. texture projector. it might take an equirectangular texture o.k., but of course the idea behind the latter is to use it on surface of sphere to illuminate what's inside sphere.

This is the U cordinate node

Quote - Okay, I did the most logical thing:  I made some test renders.

 

This is the U cordinate node

Forgive my lack of understanding :) but how did ya do that?

John

Quote - when texmap is applied to poser lite diff channel, it causes posersurfaces illum. by lite to exhibit perspective mapping according to the distance and orientation of lite.  analogous to the "perspective UVs" function in poser (camera mapping).  i.e., lite is projecting  map onto  posersurface.  intent is to map lite to produce a gel effect, but result is to cause posersurfaces to have multiplied perspective texture.  like slide projectors they useta put kodachromes in, before film went extinct.

hence a point lite with texmap becomes a 360 deg. texture projector. it might take an equirectangular texture o.k., but of course the idea behind the latter is to use it on surface of sphere to illuminate what's inside sphere.

I think it's going to take me some time to grasp that :)  Square map right?

Of course these were done against a square and not an inverted sphere.  I'm tempted to say there's some procedural method that determines how the light looks and not a map, but I need a little more info.

Quote - Forgive my lack of understanding :) but how did ya do that?

John

I plugged the U cord into the light and I put the light at 1.000 zTrans while a simple square was at -1.  Move it further away and it'll start to look more normal.  I'm really tempted to say right now that the output of the light is more a function of angle and distance between the light, the object, and the viewer more than anything else.

Quote - > Quote - Forgive my lack of understanding :) but how did ya do that?

John

 

I plugged the U cord into the light and I put the light at 1.000 zTrans while a simple square was at -1.  Move it further away and it'll start to look more normal.  I'm really tempted to say right now that the output of the light is more a function of angle and distance between the light, the object, and the viewer more than anything else.

Thanks for that, while I'm not 100% sure I comprehend completely I think with some experimentation I'll get there.  Thanks for lighting the way Winterclaw :)

John

I have never tried UV on a point light! I am learning new stuff.

I know on a spot light it's a circumscribed square, where the corners do not get involved. If we consider a circle in the UV space, I know that radius = 0 corresponds with the exact point line at the center of the light cone, and radius = .5 corresponds with the edge of the light cone. I can't remember which direction is "up" - it depends on the orientation of the light if I recall correctly.

The exact ratio of cone angle versus UV radius is unclear to me. It's not linear. What I mean by that is that if you consider a UV circle at radius = .25, this is not half the cone angle. I was trying to figure this out in detail a few months ago because I was building a Python script that could generate a Poser spotlight that produced the correct distribution specified in an IES light. Through various experiments I got really close, but not exact. One of the problems I had is that if you try to make a spotlight with a 180 degree cone, it fails.

@ Winterclaw:  regarding the first two images, it looks like perhaps U is out of phase from V, in the same way that sine is out of phase from cosine.  Same shape, different rotation?

I might have to experiment a bit with this.  But first, finish pizza...

@BB:  Just offhand, I believe the Poser spotlight is limited to 160 degrees.  Unless you meant a hypothetical cone asymptotically approaching 180', in which case, never mind.

The 160 degree limit is editable as with any property limit.

Once you set it to 180, you can try making a light that has a 180 degree cone. I found it possible to use 179, but not 180.

Thanks to everyone for your input, it seems like a much harder question than I had first anticipated :)

I thought that it may have a spherical map on it that could be used, but it looks more complex than that.

Though from BBills post it at least looks like some experimentation with a cluster of spolights might do the job :)

Special thanks to Winterclaw for his experimentation and renders, I think I might even understand those.

John.