How to blur shadows - skydome with hdri map maxtoA?

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Dina A asked Jun 21, '20

How to blur shadows - skydome with hdri map maxtoA?

Hi,

I am trying to make shadows more blurred, in particular to soften progressively - as they fall further from the object.

I see that it makes renders look much more realistic.

I tried using a "Decay filter" or a "light filter" with a "ambient occlusion light filter",

but it just lightened or darkened the scene without making any falloff in the shade.

I would like to know, is it possible to create shadow softening with a hdri skydome? It seems to me that an extra large sun would increase the shadow blur.

In addition, is there a way to set the contrast between the light and shadow (like Gamma in vray)?

Thank you

skydome shadow filters

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Petros Proestos · Jun 21, 2020 at 10:26 PM

wire hdri to a color correct map (osl or arnold) for tweaking gamma and

assign this to skydome.

I don't think you can intervent how an hdri emmit light+shadows, otherwise

use an arnold direct light+arnold filters to get the effect you want...

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Answer 1 · 2020-06-29T11:16:14Z

Mads Drøschler answered Jun 29, '20

Posting a new reply instead of the 12 reply deep stack.

I can do this in 2021, no problem.
Just make sure to wire it up correctly and it will work just fine.

The environment switcher has 2 maps, 1 for background the other for light, the light one can blur, while having a sharp background plate.

Here it works flawless, let me know if you are still stuck then we need to look into producing some more explicit walkthrough.

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Dina A · Jul 05, 2020 at 08:29 PM

It actually works! it does blur the shadows just as I wanted,

Thanks so much! that's amazing...

I copied the code into 3ds max 2020 and it also works, and looks natural and soft.

Thank you so much for all your efforts, and patients!!!!

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Mads Drøschler Dina A · Jul 06, 2020 at 09:31 AM

Super :)

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Dina A · Jun 29, 2020 at 06:59 PM

Great thanks,

I'm Looking forward for the maps!

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Mads Drøschler Dina A · Jun 30, 2020 at 09:42 AM

I use the map I send over and the environment switcher from 2021.

since you have 2021, can you try this? You have the file needed.
If works, then move 1 version backsaving to 2020 and try there.

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Dina A · Jun 30, 2020 at 09:57 AM

I actually tried that already and it didn't do anything,

Does it work by you?

What amount do you set in the blur section?

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Mads Drøschler Dina A · Jun 30, 2020 at 11:49 AM

blurlightarnoldOSL.zip

Attached 2021 project setup and working.

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blurlightarnoldosl.zip (248.7 KiB)

Answer 2 · 2020-06-22T08:28:40Z

Mads Drøschler answered Jun 22, '20

You can blur the map in an OSL Bitmaplook up node, but a bit of code addition is neeed, and Arnold needs to have the Auto mip map flag enabled.

This way you can control the amount of blur, and thus how soft or strong the shadows are.
Do note you cannot go the other way around, make a very soft image sharp. But thats also not what you want.

I can cook up some code for it and return in a bit with a custom shader.

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Dina A · Jun 22, 2020 at 08:34 PM

Hi Mads,

Thank you so much! That is very helpful!

I've been struggling with this issue for a few days.

I'm trying to carry out your instructions,

I can't manage to overwrite the OSL map in the folder so I copied and pasted your code, then pressed F7,

But for some reason it does not look the same as the OSL map in your image above.

And when I tried to set the blur value, the background became blurred instead of the shadow.

What am I doing wrong?

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Mads Drøschler Dina A · Jun 22, 2020 at 09:02 PM

Right, the .ui file is missing.

Technically it does not mean anything, your ui just resorts to an autoUI.

If you want to have the ui, go into the maxroot/OSL and find the .ui file, copy it to your root/plugins/OSL folder and store the osl file there as well. The same name is needed on both files. Restart max and you should have 2 environment maps in the list, original and this custom one.

For the seperation of the background and the environment, use an environment swither, there is an OSL one, and an Arnold render panel one.

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Dina A Mads Drøschler · Jun 24, 2020 at 05:26 PM

I copied the UI file and OSL and restarted max, and still don't see 2 environment maps in the list.

Why is it not working?

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Answer 3 · 2020-06-22T08:41:29Z

Mads Drøschler answered Jun 22, '20

This is the actual shader.
Download it, and overwrite the one in maxroot/OSL/ folder.
Or just open a random OSL node in max, delete all code, and copy paste this into it and press f7.

You then need to adjust the blur value on the map in the bottom shown above, and dont forget to enable Auto-mipmapping in the render panel.

https://github.com/gkmotu/OSL-Shaders/blob/master/HDRIEnviron_blur.osl

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Petros Proestos · Jun 22, 2020 at 04:11 PM

Mads my friend, I used to raise up hdri's gamma for bluring

shadows, this isn't the right way to do?

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Mads Drøschler Petros Proestos · Jun 22, 2020 at 04:24 PM

Gaussian blur is the most robust failsafe way, when you have either super bright tiny spots or "whatever"

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Answer 4 · 2020-06-22T21:36:27Z

rachid Hadj Abderrahmane answered Jun 22, '20

Really cool Mads Drøschler !
Some template & mtd file for Maya, Houdini, and Cinema4D
#Maya

#Houdini

#Cinema4D

HDRIEnviron_blur.zip

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hdrienviron-blur.zip (4.0 KiB)

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Mads Drøschler · Jun 22, 2020 at 10:02 PM

Updated the git, zip lies next to shader.
I put a general statement in top of ReadME that you typically do the 3 other host UIs.

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Answer 5 · 2021-01-26T17:23:29Z

Luiza Bochniak answered Jan 26, '21

You can blur HDRI Maps with HDR Light Studio plugin. It will even allow you to blur individual lights on a HDRI map, or if you want, a whole HDRI Map. The plugin can also be used to light your 3D scenes with area lights, and those can be blurred too.

Here is a good example of using HDR Light Studio to blur the sun on a HDRI Map to soften the shadows and reflections:

https://www.lightmap.co.uk/learning/diffuser_panel_effect/

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