CPU raytrace lights way off vs PBR

[banelinde]

Hi there,

 

I have set outdoor lights as in real life and tuned general sun and backdrop illumination as in CA tutorials.

But the outdoor lights (car headlights and street light in my scene) are massively different in PBR vs CPU raytrace (and Standard view as well).

 

I have tweeked every single "lights/sun/exposure/backdrop" option, but with no success to set "one entry" lights strength, to achieve similar illumination in PBR and CPU raytrace.

Example: In PBR Headlights are 1.200lum and Streetlight 30.000lum and everything looks fine, but to achieve the similar result in CPU and Standard view, I must multiply the lights strength 35x fold  (by guesswork).

Image no.1 and no.6 is what I'm looking for, but with "one strength setting".

 

Aghrrrrrrr!  

 

The goal is to have rough feeling of a illumination in "Standard view" while modeling, then to adjust it in "PBR", and finally to render it in "CPU raytrace" (PBR is not producing shadows for the images etc).

Otherwise, It's all pain to proceed with the work.

 

Please advise.

 

I'm using W10+X13+RTX2060

 

 

 

 

[TeaTime]

5 minutes ago, banelinde said:

to achieve similar illumination in PBR and CPU raytrace.

My understanding is that this simply is not going to happen - CPU and GPU ray tracing process lighting data in very different ways from one another, they're really not interchangeable. Standard view is a whole separate thing, its light handling is weak and is only meant to be a vague representation.

 

If you're going to be ray tracing, pick one and stick with it, otherwise you'll need different light sets for each type of rendering and--yeh, as you've discovered, will need to tweak them both completely independently from one another.

[banelinde]

7 hours ago, TeaTime said:

not going to happen - CPU and GPU ray tracing process lighting data in very different ways......

 

Standard view is a whole separate thing, its light handling is weak......

 

will need to tweak them both completely independently.......

 

TeaTime, many thanks.

 

But, CA should have these differences calculate by itself.

Consantly guessing  or having double light sets, is producing massive pain.

 

Regards.

[Kbird1]

It won't help you now I guess , but the Lighting in PBR in X15 is better and with the newly introduced Denoiser in X15, is a game changer (thankfully) it Cleans up Scenes very quickly of artifacts and Fireflies, you may even find CPU RT is no longer needed.

 

M.

[banelinde]

Kbird1, many thanks, will check.

 

But, PBR is not showing shadows for 2D images (plants etc) and has it's issues.

Same goes for CPU RT.

Looks they have bugs.

 

It would also be a pain to export the scenes to e.g. 3DS max.

 

 

[Kbird1]

9 hours ago, banelinde said:

Kbird1, many thanks, will check.

 

 

Download the Trial and see for yourself, eg all the graininess on the Drywall is removed by the Denoiser now in PBR , I no longer do CPU RTs myself , so can't help much there.

 

Also your Sun Lumens are WAY too high , which causes the backgrounds to fade out and throw color casts into the interiors and sometimes light bleed particularly in earlier versions or Plans started in earlier versions , in my experience. In RTRT try somewhere in the 5000 - 10000 Sun Lumen range and set the Daytime Intensity to the 700-1000 Range.   

 

this X15 example  is 7000 and 700 and is a 500 sample with Denoiser on and took about 35-40 secs. ( after Materials and Lighting were done for the final Image - no post processing.)

 

 

  

 

 

M/

[banelinde]

15 hours ago, Kbird1 said:

 

 

a )Download the Trial and see for yourself, eg all the graininess on the Drywall is removed by the Denoiser now in PBR , I no longer do CPU RTs myself , so can't help much there.

 

b) Also your Sun Lumens are WAY too high , which causes the backgrounds to fade out and throw color casts into the interiors and sometimes light bleed particularly in earlier versions or Plans started in earlier versions , in my experience. In RTRT try somewhere in the 5000 - 10000 Sun Lumen range and set the Daytime Intensity to the 700-1000 Range.   

c) this X15 example  is 7000 and 700 and is a 500 sample with Denoiser on and took about 35-40 secs. ( after Materials and Lighting were done for the final Image - no post processing.)

 

 

Kbird1, many, many thanks.

 

a) have done it and the real novelty for the PBR is the Denoiser. Top.

     But, the lights calculation in CPU vs PBR are still off. Still no shadows for 2D images, eg plants in PBR. The shadows in PBR still often no-go.

 

b) you missed it, the sun with extra LUM was a entry to achieve similar light brightness falling on the floor in CPU render, to be as in PBR

 

c) yes, I done that already, as it was in the CA tutorials.

[banelinde]

Grainy shadow map in PBR X15

Even the large circle shadows should not be there (look the CPU below)

 

 

To achieve similar illumination, water self illumination must be cranked up to 300.000lum in CPU X15

The backdrop less then 0,1 in CPU is not possible and still to bright.

 

 

[Kbird1]

6 hours ago, banelinde said:

 

 

Kbird1, many, many thanks.

 

a) have done it and the real novelty for the PBR is the Denoiser. Top.

     But, the lights calculation in CPU vs PBR are still off. Still no shadows for 2D images, eg plants in PBR. The shadows in PBR still often no-go.

 

b) you missed it, the sun with extra LUM was a entry to achieve similar light brightness falling on the floor in CPU render, to be as in PBR

 

c) yes, I done that already, as it was in the CA tutorials.

 

 

A.) CPU and RAY Trace light will never been the same as they work differently , and Chief is slowly depreciating the CPU Tracer which is now 20yrs (?) old so most people have switched to PBR-RTRT due to it's speed and learning to get the best out of it... does it need improvements? yes but it is worthwhile using in X15 I think.

 

also The advice is to use 3D plants for now at least, has been since X13.

 

You could try turning OFF the Ray Cast Shadows ( hard shadows) and see if it gives "softer" edges to the shadows instead of those jagged edges.

 

B.)  The Lums are just too High  for PBR ( not standard views)   and should perhaps in your case be  10,000 and 35,0000 , not 100,000 and 3,500,000  (at a guess)  the Lum. values are not real world and automatic balance themselves to the other lighting in the Plan , so it does take a bit of playing to get it right , and won't be the same in every Plan , or even scene , it can even change if the camera angleis changed or the camera moved 12".

 

C.)  And where do you think the CA Tutorials got their info ?     ...... here on the Forum of course from Users posting there fixes and solutions...

 

 

Mick.