Noise when using lights

[JTrusty]

I am getting some terrible noise in my renders when using lights.

You can see the noise on the ground plane, on the reflector cone and trim ring.

Basically, when light is cast on any non-matte material, I am getting lots of noise.

This isn't a settings issue, nor is it an issue with render duration.

[thomasteger]

This should be better in KeyShot 5. It has been released today.

[JTrusty]

Thomas,

Artifacts from area, point and IES are neither fixed nor "better" in KS5.

I have submitted a .ksp file through https://keyshot.wetransfer.com/ for you to look at. Also, there are more issues at play with point, area and IES lights than just the artifacts / noise.

[thomasteger]

We will take a look. I assume you sent it to support?

[JTrusty]

We will take a look.

Thanks.

I assume you sent it to support?

Correct.

[JTrusty]

Light does not behave this way.

https://www.facebook.com/photo.php?v=866787443337610&l=3819388834991642252

When you change your viewing angle, the emitted light should not change direction.

This issue is further evidenced when you change to an IES profile and turn on the wireframe for the light. Rotate the viewport and you can see the wireframe ( light ) change direction

[DriesV]

Light does not behave this way.

https://www.facebook.com/photo.php?v=866787443337610&l=3819388834991642252

When you change your viewing angle, the emitted light should not change direction.

This issue is further evidenced when you change to an IES profile and turn on the wireframe for the light. Rotate the viewport and you can see the wireframe ( light ) change direction

For all I know, that's just the specular highlight of the point light. Point lights have no direction.
If you want to go absolutely physically correct, you should be using an area light.

Dries

[JTrusty]

...that's just the specular highlight of the point light.

You are correct.

Point lights have no direction.

Did not know that, thanks!

If you want to go absolutely physically correct, you should be using an area light.

I switched to area light and light behavior seems correct. However, artifacts are still very bad.

Further, to get the correct output I have to use 200 watts. The output at the emitter is measured at 320 lumens, but when using lumens, 320 emits nearly nothing.

[DriesV]

Can you upload the scene here (KS package, ksp)?
I would love to give it a go.

Dries

[JTrusty]

Can you upload the scene here (KS package, ksp)?

Attached.

I will be amazed if you can correct the noise / artifacts issue considering there is an ongoing thread regarding this in the rants subforum identifying an existing problem with lights since keyshot 4.x 

[KeyShot]

The issue in this scene is that you have a small painted chip right next to the light source - both are encapsulated in glass. This in effect makes the paint chip a secondary light source for caustics, which does cause noise in the output. We do have some new techniques in the pipeline that will address this issue, but for now your best option is to either make it a metal chip rather than a painted diffuse chip - you can also hide it since the overall effect is minimal (except for the noise).  There is also a little noise from the leather material having a fine procedural bump map. This can be fixed by using a bump map texture or normal map texture instead.

The noise will go away eventually, but it does cause a slower convergence than normal in the scene.

Thanks for sharing the scene though. We will make sure to further optimize KeyShot for this kind of setup.

[JTrusty]

...but for now your best option is to either make it a metal chip rather than a painted diffuse chip

Simply switching the chip from painted diffuse to metal solve all the noise artifacts! Thanks for the tip.

Any thoughts as to why the output when measured in lumens is incorrect / weak? Also, why doesn't the beam "throw" further across the ground plane than a few inches? In reality the light casts much further across the planar surface.

[DriesV]

Darn, Henrik beat me to it.

Also, it seems to me that the Leather material doesn't catch caustics. Change the ground plane material to something else (say, a plastic) and then caustics should be visible. The light intensity will also be higher. Maybe that solves your "beam throw" issue too. Otherwise you can try changing scene units.

Dries

[DriesV]

Here's my quick version of this scene.
I could get a better result with some modifications on the CAD level...

Dries

[JTrusty]

Here is the original product shot I did for our website:



Here is a photograph of a similar light and beam pattern:



And here is my supplemental product shot that is working now without artifacts: