How to get soft shadows of IES lights? ... a wish

[Micha_cg]

I don't found an option, so maybe it can be implemented for the future. Or is there a trick?

-Micha

[merlik585]

Re: How to get soft shadows of IES lights? ... a wish

In a way yes,at the bottom of the light propertie box there is a switch.But it is not very useful the difference,their is a one is very very subtle,,even setting the suddivisions very very high don't do much.I think there is a major upgrade to do on the IES lights,

Renee

[Micha_cg]

Re: How to get soft shadows of IES lights? ... a wish

Ah, I have complete overseen. I was looking for a radius option. How can be controlled the softness?

[Micha_cg]

Re: How to get soft shadows of IES lights? ... a wish

I tested the soft shadow option during my current project and it works quite good here. The shadows are less sharp and more real. But how is the light source size defined? Or is the option only forgotten by the developer, but internal set to a constant value?

[Micha_cg]

Re: How to get soft shadows of IES lights? ... a wish

In a way yes,at the bottom of the light propertie box there is a switch.But it is not very useful the difference,their is a one is very very subtle,,even setting the suddivisions very very high don't do much.I think there is a major upgrade to do on the IES lights,

Renee

It works, but it could be that the light source size is internal fixed. My current scene units are mm and I see a good visible smoothing. I have the feeling the linternal fixed ight source size is approx. 30..50 mm. But the calculation is quite slow.

[merlik585]

Re: How to get soft shadows of IES lights? ... a wish

may be I don't know,but I was under the impression that the major part of smoothing was done by the IES file definition itself,
Some are much more smooth than other.

smoothness,brightness diffusion angle of light are all part of the IES file.

[dalomar_cg]

Re: How to get soft shadows of IES lights? ... a wish

Smoothing is not part of the IES definition. IES files describe distribution intensities and that's it (so how much light is coming from what direction). In order to have shadow smoothing there needs to be a size to the light source, so that V-Ray can know how that size affects the resulting shadow. This is handled through the radius option, which should use scene units as the value for determining the size of the light. I think the "smoothness" you're thinking about is just how much variation there is within those distribution intensities which depends on the ies light itself.

I do think it would be nice if IES files actually had a little more information than they currently do. For instance, the color temperature would be very nice to have either globally or described with the distribution. Also, the current distribution is essentially radial, and it would be nice the distribution was described in completely 3dimenisonal terms. But since I'm not a member of the illumination engineering society, I doubt they'll listen to me

[Micha_cg]

Re: How to get soft shadows of IES lights? ... a wish

Damien, did you have seen that there is no radius option for IES lights?

If I use IES lights than I very much miss the control over light source size (radius) and intensity.

[dalomar_cg]

Re: How to get soft shadows of IES lights? ... a wish

I know its not there. The reason being (I would assume) that how would V-Ray know what intensity is coming from the given sample area? IES lights are essentially point lights with varying intensities, so how would you determine the intensity of the light is from any place other than that point in space.

As a note, the IES functionality is not exposed to us at the moment. We just have the plugin provided to us from the Chaos Group and feed parameters into it. This request, along with adjusting intensity, is something that can really only be handled within the plugin itself.

[Micha_cg]

Re: How to get soft shadows of IES lights? ... a wish

I know its not there. The reason being (I would assume) that how would V-Ray know what intensity is coming from the given sample area? IES lights are essentially point lights with varying intensities, so how would you determine the intensity of the light is from any place other than that point in space.

I think it's no problem for CG. From what I understand about point light soft shadows, the calculation is done like a cloud of point lights is there. So, I suppose so, in the easiest case it would be for IES lights the same. You write " adjusting intensity, is something that can really only be handled within the plugin itself". Is the radius possible and if yes, should I send a wish request per support tracker or is it on the list?

[dalomar_cg]

Re: How to get soft shadows of IES lights? ... a wish

That's certainly a possible solution. You could also just use the same intensity value traced from a different physical point in space. That may be a little simpler, but I don't know. Anyway, I wasn't saying that it couldn't be done, just that it would require access to the source code in order to do it. If the Chaos Group gives us access to it, then I we could certainly take care of it.

[Micha_cg]

Re: How to get soft shadows of IES lights? ... a wish

So, you say, the radius isn't supported by the SDK, right?

[dalomar_cg]

Re: How to get soft shadows of IES lights? ... a wish

nope, no radius option in the SDK for ies lights

[Micha_cg]

Re: How to get soft shadows of IES lights? ... a wish

Ah, ok, so Vlados team could help here only.

[dalomar_cg]

Re: How to get soft shadows of IES lights? ... a wish

We could do it if they provided us the source code. From time to time they do that for us.