IRay: Grainy pictures

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Re: IRay: Grainy pictures

Postby Mortze » Fri, 18Feb02 00:49

Those dots are iterations that still have to be done.
I'm guessing that model, and the other one, have Translucency parameters. Translucency is heavy on the calculations, much like reflective or transparent materials, like glass or mirror. You can see that the reflective surface on the purple and blue frames, as well as the black poster also have the dots. The walls and the bed don't because those are easy calculations.

The right balance between render time and end result is subjective of what the artist desires as his objectives.
My criteria is that I want to make pretty pictures, with good quality, but in a rational time so that I can release a game in months and not in years. Because of that I have to "accept" some decrease in quality in my pictures.
You have to decide what are your criteria. If you don't mind the time then pump up those iterations. My standard iteration number is 5000. Sometimes my pic is done under that number, sometimes I must push it to 10000 or 15000.
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Re: IRay: Grainy pictures

Postby always86 » Fri, 18Feb02 01:04

The odd thing is that last one was given the chance to render for as long as it needed or as many iterations. It should have been able to go for 80+ mins or 5000 iterations. instead it finished in 30 mins with 1300. My problem with going for 5000 is that could take hours.

I know you have a more powerful rig but how long does it take you on a typical image to do 5000?
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Re: IRay: Grainy pictures

Postby Mortze » Fri, 18Feb02 15:41

always86 wrote:The odd thing is that last one was given the chance to render for as long as it needed or as many iterations. It should have been able to go for 80+ mins or 5000 iterations. instead it finished in 30 mins with 1300. My problem with going for 5000 is that could take hours.

To avoid that you must define the absolute minimum iterations you want the GPU to make. Go to your Render Settings, Progressive Rendering, and where it says Min Samples (default 5) you must have to put a much higher number. It maxes to 100 so you must go to the wheel on the right of that parameter, Parameter Settings, and uncheck Use Limits. Then put a value of 10000 for example, and the rendering won't stop until you reach 10000 samples (iterations) no matter what.

always86 wrote:My problem with going for 5000 is that could take hours.

What kind of lighting are you using? Use Mesh lights instead of emissive surfaces. Delete any geometry that isn't in the camera shot (save for walls and ceiling).
Is your model on High Definition and with many SubDivisions?

always86 wrote:I know you have a more powerful rig but how long does it take you on a typical image to do 5000?

That depends on what's in the scene, what lighting I use, and my picture resolution. Rendering time isn't exclusively related to the number of samples (iterations).
For my game pictures I don't accept more than 30 minutes. For other pictures I will go as much as 1 hour. Default is always 5000 samples but I boost the number whenever necessary.
On average I do a picture in 12 minutes.
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Re: IRay: Grainy pictures

Postby Greyelf » Fri, 18Feb02 23:04

Mortze wrote:Delete any geometry that isn't in the camera shot (save for walls and ceiling).

Is it enough to hide that geometry within the scene or do you need to actually delete it from the scene?
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Re: IRay: Grainy pictures

Postby Mortze » Fri, 18Feb02 23:20

Greyelf wrote:Mortze wrote:
Delete any geometry that isn't in the camera shot (save for walls and ceiling).

Is it enough to hide that geometry within the scene or do you need to actually delete it from the scene?


Better still: delete it, save the file, restart DAZ, load the file and render it.

Hidden and deleted files remain in the RAM.
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Re: IRay: Grainy pictures

Postby Greyelf » Fri, 18Feb02 23:30

Mortze wrote:Better still: delete it, save the file, restart DAZ, load the file and render it.
Hidden and deleted files remain in the RAM.

So if you were going to use the same location (eg room) from two different camera angles, would you generally:

a. Create two different scenes, each containing only the visible geometry plus the walls.
b. Create one scene containing only the visible geometry used by both camera angles plus the walls.
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Re: IRay: Grainy pictures

Postby Mortze » Sat, 18Feb03 21:27

Greyelf wrote:So if you were going to use the same location (eg room) from two different camera angles, would you generally:

a. Create two different scenes, each containing only the visible geometry plus the walls.
b. Create one scene containing only the visible geometry used by both camera angles plus the walls.


If I want to save rendering time then option a.

But keep in mind that if you have reflective surfaces on your camera shot you might need to put reflections there. A reflection map should do the trick but if you don't want to use that you'll have to keep the reflected objects in the scene.

I would also remove walls, ceiling and floor and work only with spotlights and pointlights. You cheat the lack of reflective geometry with the appropriate lighting. Basically, treat your scene like a real professional photography studio or like the old movie sets.
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Re: IRay: Grainy pictures

Postby MaxCarna » Sat, 18Feb03 23:02

I recently bought this product https://www.daz3d.com/iray-ghost-light-kit 60% off

It seems to improve the render time and reduce grainy. I'm still studying it, making some tests, but it promises a lot.
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Re: IRay: Grainy pictures

Postby Mortze » Sun, 18Feb04 16:24

MaxCarna wrote:I recently bought this product https://www.daz3d.com/iray-ghost-light-kit 60% off

It seems to improve the render time and reduce grainy. I'm still studying it, making some tests, but it promises a lot.


Could you do a test for me please?
Make a scene with an interior, like a living room or a kitchen, and have the Iray Ghost Light Kit light the room from a window or two, and also with a little lamp against a wall.

Then, remove that Kit and use normal Mesh Lights, a rectangular spotlight for the window and a pointlight for the lamp. Try to duplicate the light temperature and lumens to the same values as the Kit.
Let me know if there's a significant difference in time rendering.
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Re: IRay: Grainy pictures

Postby MaxCarna » Sun, 18Feb04 16:44

Mortze wrote:Could you do a test for me please?


Using Dome and Scene lights, or only scene?

If there is a external light, you suggest the configuration?
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Re: IRay: Grainy pictures

Postby Mortze » Sun, 18Feb04 18:07

Just Scene. No HDRI.
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Re: IRay: Grainy pictures

Postby MaxCarna » Sun, 18Feb04 19:35

I'm on it, I will bring the results soon as I'm done
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Re: IRay: Grainy pictures

Postby Mortze » Sun, 18Feb04 20:58

MaxCarna wrote:I'm on it, I will bring the results soon as I'm done

Thank you.
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Re: IRay: Grainy pictures

Postby MaxCarna » Sun, 18Feb04 21:32

Ok, here we go

I tried to apply the same light settings, but the final results are different, so maybe you can point me what I have to change

4x windows - Vertical Ghost Light
Emission Temperature 5000.0
Luminance 3000000.0
Luminance Units lm

1x wall light - Horizontal Ghost Light
Emission Temperature 6000.0
Luminance 50000.0
Luminance Units lm

Time to render: 1 minutes 10.18 seconds

This is the Ghost Light Setup
Image

This is the final result
Image

4x windows - Spotlight
Light Geometry Rectangle
Height 230.00
Width 90.00 (middle) 150.00 (sides)
Intensity 100%
Luminous Flux (Lumen) 3000000.0
Temperature 5000.0
Render Emitter Off

1x wall light - Point light
Intensity 100%
Luminous Flux (Lumen) 50000.0
Temperature 60000.0
Render Emitter On

Time to render 8 minutes 21.44 seconds

This is the Mesh Light Setup
Image

This is the final result
Image

I am using Ryzen 7 1700, 64gb RAM, 2x Geforce 1070
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Re: IRay: Grainy pictures

Postby Mortze » Sun, 18Feb04 23:09

Try to change the Spothlights Spread Angle to 175. Let me know if it changed the rendering time.
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