Corona Renderer Forum

Corona Renderer for 3ds Max => [Max] I need help! => Topic started by: M Nabil on 2020-09-10, 09:36:16

Title: Render Time
Post by: M Nabil on 2020-09-10, 09:36:16
Hi Everybody
I need to understand something about how corona renderer work, if I set the light intensity to lower-value e.g. 0.3, and increase the (EV)  in the frame buffer to get the perfect light, Will this method take too much time in rendering because the scene is already a little dark or it the same if I set the light intensity to 1 and EV to 0, and what is the cons that will affect my scene regarding using this method not just render time may be about the quality of achieving realistic render.
Thank you
Title: Re: Render Time
Post by: sprayer on 2020-09-10, 18:07:16
To be short, setup light for EV 0 in interior, and EV -4 for exterior. Of cause if you try to light up the room with one burning match it will be too noisy like in real photo
Title: Re: Render Time
Post by: GeorgeK on 2020-09-11, 10:19:07
Overall scene albedo plays a big role in lighting composition and render times as well. In the following fringe example, there is an indirect light with fixed intensity.

Image Comparer: https://corona-renderer.com/comparer/rqq85A

For the second example with an interior hidden wall light (direct), same materials.

Image Comparer: https://corona-renderer.com/comparer/fBcZTL
Title: Re: Render Time
Post by: agentdark45 on 2020-09-11, 13:54:40
Overall scene albedo plays a big role in lighting composition and render times as well. In the following fringe example, there is an indirect light with fixed intensity.

Image Comparer: https://corona-renderer.com/comparer/rqq85A
  • On the left image, you will see an interior with 200RGB diffuse material, 0 global EV. finished in 9min 46 sec. at 19.8mil. rays/sec with 1.98% image noise.
  • On the right, an interior with 150RGB diffuse material, 3.5 global EV. finished in 18min. at 19mil. rays/sec with 2% image noise.

For the second example with an interior hidden wall light (direct), same materials.

Image Comparer: https://corona-renderer.com/comparer/fBcZTL
  • On the left image, you will see an interior with 200RGB diffuse material, 0 global EV. finished in 49 sec. at 23.3mil. rays/sec with 3.55% image noise.
  • On the right, an interior with 150RGB diffuse material, 2.0 global EV. finished in 1.2min. at 22.6mil. rays/sec with 3.93% image noise.

Very interesting tests!

This has probably been discussed a million times before, but for a typical white wall is the "stick to 200rgb" rule still sound? What are the upper limit rbg diffuse values before things start going beyond reality?
Title: Re: Render Time
Post by: GeorgeK on 2020-09-11, 19:49:56
Overall scene albedo plays a big role in lighting composition and render times as well. In the following fringe example, there is an indirect light with fixed intensity.

Image Comparer: https://corona-renderer.com/comparer/rqq85A
  • On the left image, you will see an interior with 200RGB diffuse material, 0 global EV. finished in 9min 46 sec. at 19.8mil. rays/sec with 1.98% image noise.
  • On the right, an interior with 150RGB diffuse material, 3.5 global EV. finished in 18min. at 19mil. rays/sec with 2% image noise.

For the second example with an interior hidden wall light (direct), same materials.

Image Comparer: https://corona-renderer.com/comparer/fBcZTL
  • On the left image, you will see an interior with 200RGB diffuse material, 0 global EV. finished in 49 sec. at 23.3mil. rays/sec with 3.55% image noise.
  • On the right, an interior with 150RGB diffuse material, 2.0 global EV. finished in 1.2min. at 22.6mil. rays/sec with 3.93% image noise.

Very interesting tests!

This has probably been discussed a million times before, but for a typical white wall is the "stick to 200rgb" rule still sound? What are the upper limit rbg diffuse values before things start going beyond reality?

Personally I believe anything bellow 225 is acceptable, but it really depends on so many things.
Title: Re: Render Time
Post by: Bormax on 2020-09-11, 20:11:22
Hm, interesting. From my quick tests obvious conclusion is - brighter albedo -> shorter render time with the same noise limit, less passes to reach that noise limit.
Is it because of light energy loss while bouncing from the darker objects?
Title: Re: Render Time
Post by: M Nabil on 2020-09-13, 08:48:46
Thank you  guys,
Just to be clear about what you've mentioned above, low-intensity light whatever it's an exterior or interior scene with increased EV value will cause a long render time, and the albedo playing a big role on render as well.