render quality and time

abunezek

https://drive.google.com/file/d/124kLYLdd7FoOwjDIlUsLXbjhcLb5v8no/view?usp=sharing

this image (1920x1080) was redered using iray, it took 57 minutes to render  2500 iterations.

my gpu card is gtx 1080. 

is this normal? 

the quality is not that good and there is grain(filter is on) and fireflyes(filter is on)...

am i doing something wrong?

i read and saw many videos about rendering tips, didnt found anything meaningful.

maybe i'm doing it right and i just need to render mire time?

 

Thanks

SimonJM

It will tend to happen if, as you have, there are a lot of light sources and a large set of reflective/glossy surfaces.  More time would likely help, yes.

Toonces

Very normal for a single gpu, especially since your scene is dark. You can either set it to render overnight, or switch to faster lighting from fewer sources (e.g., ghost/mesh lights or hdri...the latter would need ceiling/wall hiding).

abunezek

hi and thanks for the fast response.

i remove all lights from scene and turned on the cameras headlight.

same render took 48 minutes so thats not the main issue.

 

Silver Dolphin

Adding lights does not make Iray take longer. If you are doing night scenes I would use an old hollywood trick of making the light blue to simulate darkness. Using HDRI images for lights makes Iray renders faster or add more video cards. I would render really large and use Gimp or photoshop to resize down and you should get what you are looking for.  Enclosed scenes and dark renders are best done in 3delight and just render the subject or model in Iray and use Gimp or photoshop to composite image. Mesh lights work great as well but turn opacity of mesh to .001 so it does not show up in render.

JonnyRay

What you're seeing is a common issue in Physically Based Rendering (PBR) engines. More time may help. But adjusting the lighting may be your best bet.

Because I routinely render things where I want to have dramatic lighting with darkened areas, I typically use Silver Dolphin's trick of rendering at 150% to 200% of the final image size that I really want. Downsampling the image tends to average out a lot of the fireflies.

Also, I've found lately that on the tone mapping part of the Render Settings tab, if I turn off the Black and White limits (set both to zero) and set the Gamma to 1.0, then I can adjust the final exposure easier in post production witn GIMP and get the look I want rather than relying on the limited range that the rendering engine wants to give me.

hphoenix

abunezek said:

https://drive.google.com/file/d/124kLYLdd7FoOwjDIlUsLXbjhcLb5v8no/view?usp=sharing

this image (1920x1080) was redered using iray, it took 57 minutes to render  2500 iterations.

my gpu card is gtx 1080. 

is this normal? 

the quality is not that good and there is grain(filter is on) and fireflyes(filter is on)...

am i doing something wrong?

i read and saw many videos about rendering tips, didnt found anything meaningful.

maybe i'm doing it right and i just need to render mire time?

 

Thanks

IRAY likes light.  A lot of it.  Low-light scenes (where the actual values of the lights is low) take a LONG time to get rid of grain and fireflies.  You would be better off using increased light values and then dimming the image in post-processing.  Lots of reflective or refractive surfaces will also increase render time considerably.  Also, for indoor scenes, use the architectural sampler optimization.  Put actual IES profiles on the lights, so they don't produce omnidirectional light (and thus increase calculation time for little benefit in areas where things are blocked by shades and such.)

Such a scene, even in 3Delight, with the advanced lights and shaders needed to properly handle refractions/transparency and diffuse lighting?  They can actually be a lot SLOWER.

 

abunezek

hphoenix said:

abunezek said:

 

  You would be better off using increased light values and then dimming the image in post-processing.  L

its actually a very nice idea. 

I will try this, thanks

JonnyRay

Also, if you're using HRDI lighting, in the Render Settings -> Environment tab, you can increase the intensity of the environment light. Depending on conditions, I routinely increase this to a value of 3 - 5. I can always tone it down later if I need to, but the additional light seems to help my rendering times a little as well.

Toonces

I wonder what's the difference between Environment Intensity slider and the slider on the environment map itself. Both seem to increase the amount of HDRI lighting.

JonnyRay

Toonces said:

I wonder what's the difference between Environment Intensity slider and the slider on the environment map itself. Both seem to increase the amount of HDRI lighting.

I don't know. I've only used the Environment Intensity slider. I never even noticed there was a slider on the map parameter. :)