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IES file and soft shadow
Posted: Thu Feb 08, 2018 3:45 pm
by marcatore
I've tested the IES feature with a point light (I've used this kind of light because I can hide the source, if I use the area light I have the area light mesh visible) but it seems that I can't achieve soft shadows.
Is it something wrong with my setup or is it designed in his way? Is it the correct kind of light if I want to use the IES feature?
Re: IES file and soft shadow
Posted: Thu Feb 08, 2018 4:28 pm
by Dade
marcatore wrote: Thu Feb 08, 2018 3:45 pm
I've tested the IES feature with a point light (I've used this kind of light because I can hide the source, if I use the area light I have the area light mesh visible) but it seems that I can't achieve soft shadows.
Is it something wrong with my setup or is it designed in his way? Is it the correct kind of light if I want to use the IES feature?
A IES profile varies only the intensity of the emitted light and you can not have soft shadows with a point light (doesn't matter how the intensity varies and if you use or not an IES profile).
A spherical light source (a point light with a radius) could somewhat fix your problem but it is not yet supported:
https://github.com/LuxCoreRender/LuxCore/issues/57
Re: IES file and soft shadow
Posted: Tue Feb 13, 2018 8:14 am
by marcatore
@Dade
Just a premise. I know Luxcore team is a really really small team so , please, consider what I'm reporting just a contribution to the thread. It's not a "make this or luxcore is a s..t"
.
My daily render engine is Vray and it offers the opportunity to use the IES "shape" for several purpose.
From the online manual
https://docs.chaosgroup.com/display/VRA ... 7C+VRayIES
"use light shape – Determines whether and how the shape of the light specified in the .ies light will be taken into consideration during the calculation of shadows and illumination.
No – The light shape will not be considered for illumination and the light is going to generate sharp shadows.
For shadows – The light shape will be considered only for the generation of soft shadows. The illumination will not be affected by the light shape (i.e. it will behave as a point light).
For illumination and shadows – The light shape will be considered for the calculation of the illumination and shadows."
I'm just saying it should be useful to have something like this. If not, no problem. Probably I know why.
About the solution of the spherical light source, the light source with a radius will be visible like the area light?
Re: IES file and soft shadow
Posted: Tue Feb 13, 2018 9:50 am
by Dade
marcatore wrote: Tue Feb 13, 2018 8:14 am
@Dade
Just a premise. I know Luxcore team is a really really small team so , please, consider what I'm reporting just a contribution to the thread. It's not a "make this or luxcore is a s..t"
.
My daily render engine is Vray and it offers the opportunity to use the IES "shape" for several purpose.
From the online manual
https://docs.chaosgroup.com/display/VRA ... 7C+VRayIES
"use light shape – Determines whether and how the shape of the light specified in the .ies light will be taken into consideration during the calculation of shadows and illumination.
No – The light shape will not be considered for illumination and the light is going to generate sharp shadows.
For shadows – The light shape will be considered only for the generation of soft shadows. The illumination will not be affected by the light shape (i.e. it will behave as a point light).
For illumination and shadows – The light shape will be considered for the calculation of the illumination and shadows."
I had the IES specification somewhere, I don't remember the section about the shape but I guess is there or has been introduced in a newer version. Anyway it is interesting and it is something can be added in the future. The relevant part of the Vray documentation:
Code: Select all
use light shape – Determines whether and how the shape of the light specified in the .ies light will be taken into consideration during the calculation of shadows and illumination.
No – The light shape will not be considered for illumination and the light is going to generate sharp shadows.
For shadows – The light shape will be considered only for the generation of soft shadows. The illumination will not be affected by the light shape (i.e. it will behave as a point light).
For illumination and shadows – The light shape will be considered for the calculation of the illumination and shadows.
override shape – When enabled, the light profile within the .ies file is ignored. The shape parameter defines the light shape for calculating shadow softness, otherwise IES lights will generate shadows as a point light, casting sharp shadows.
shape – Specifies a shape (and its orientation) for the IES light when override shape is enabled. Some shapes (shown below) enable additional options for size.
point
rectangle
circle
sphere
vertical cylinder
horizontal cylinder (length)
horizontal cylinder (width)
ellipse (length)
ellipse (width)
ellipsoid (length)
ellipsoid (width)
marcatore wrote: Tue Feb 13, 2018 8:14 am
About the solution of the spherical light source, the light source with a radius will be visible like the area light?
No, it would be a not intersectable light source like point light. Anyway it would be a partial implementation of the shape concept described above.
Re: IES file and soft shadow
Posted: Tue Feb 13, 2018 10:24 am
by marcatore
Good. I hope to see this in the future.
About the visible shape I think it's always a pity to have it necessarily visible because it force you to build the 3d model of the light to visually justify the floating (imagine an interior render scenario) bright disc (or rectangle of an area light) and sometimes there are situation where you don't need that kind of details.
Anyway I'll never ask you again in the future cause probably it's how it works the render engine and I think I'm going to be annoying.
Re: IES file and soft shadow
Posted: Tue Feb 13, 2018 10:52 am
by B.Y.O.B.
Yes, sometimes I also wish we had a non-intersectible area light that is invisible to the camera (and sometimes also invisible in specular/glossy reflections).
Re: IES file and soft shadow
Posted: Tue Feb 13, 2018 11:40 am
by Dade
B.Y.O.B. wrote: Tue Feb 13, 2018 10:52 am
Yes, sometimes I also wish we had a non-intersectible area light that is invisible to the camera (and sometimes also invisible in specular/glossy reflections).
All non-intersectable (point, spot, laser, etc.) light are invisible to the camera and in specular reflections however area light are visible because they are intersectable (i.e. we lack of non-intersectible area light).
Side note: people often forgot that intersectable area lights can be sampled in multiple way and it reduces the noise thanks to MIS (multiple importance sampling). The same scene rendered with non-intersectable area light can have a lot more noise than one with intersectable area light.
Camera invisible objects are another possible solution to the problem (probably better than non-intersectible area light).
Re: IES file and soft shadow
Posted: Tue Feb 13, 2018 12:09 pm
by B.Y.O.B.
Dade wrote: Tue Feb 13, 2018 11:40 am
Camera invisible objects are another possible solution to the problem (probably better than non-intersectible area light).
If possible this would be enough for most use cases I think.
Of course it's a bit of a bad idea to add a new invisible, but very noisy area light
Re: IES file and soft shadow
Posted: Tue Feb 13, 2018 1:00 pm
by marcatore
Yes, I think it could be enough.