Luxcore render result with blender cycle result? what i did wrong here?

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richardbao
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Luxcore render result with blender cycle result? what i did wrong here?

Post by richardbao » Sat May 29, 2021 4:39 am

the following render results were using the same scene with same HDRI lighting.
the first one was rendered with blender cycle(no AI denoise)
the second one was done with luxcore(no AI denoise) that we integrated in our 3d software.
Screenshot 2021-05-29 123217.png
Slot_5.png
the cycle one looks more clean and tone looks better.
the luxcore one looks yellowish and it feels like a filter been applied to the image.
and the image contrast looks way better on the cycle one. i was wondering if its the reason of tonemapping or color mangement?
what i did wrong on this? did i miss something while integrating the luxcore?
any suggestion would be appreciated!

CodeHD
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Re: Luxcore render result with blender cycle result? what i did wrong here?

Post by CodeHD » Sat May 29, 2021 8:36 am

To me it looks like there are significant differences in material setup that can be addressed.

First example is the table in the front. In the cycles render, it looks smooth and like a typical table furnish. In Luxcore, it looks like bump mapping is very excessive, and it looks more like outdoor teak wood structure.

Second example is the wall behind the bed, where a lot of the contrast difference is found. Here, cycles shows a lot of texture, while in LuxCore it is flat. So maybe adjust the contrast of the shader there. A lot of light seems to be going to the left wall (which we don't see), so if the wall shader is brighter, it could lead to more scattering around the room.

Regarding tonemapping and color management, I don't really have expereicen to talk about. Maybe someone else here has practical experience with typical settings issues.

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Re: Luxcore render result with blender cycle result? what i did wrong here?

Post by Martini » Sat May 29, 2021 8:58 am

richardbao wrote:
Sat May 29, 2021 4:39 am
the following render results were using the same scene with same HDRI lighting.
the first one was rendered with blender cycle(no AI denoise)
the second one was done with luxcore(no AI denoise) that we integrated in our 3d software.
Can you render it with LuxCore in Blender? To rule out the possibility that the error is a setting in your 3d software.
richardbao wrote:
Sat May 29, 2021 4:39 am
the cycle one looks more clean and tone looks better.
the luxcore one looks yellowish and it feels like a filter been applied to the image.
To me, it looks like your LuxCore render also has way more bounces than Cycles. Can you check the light path settings are using the same number of bounces? You didn't mention whether you were using Path tracing or BiDir, if using BiDir then total bounces = light + camera.

Also Cycles render is way darker. What gamma is applied on your HDR? Check that it's 1.0 and not 2.2.
richardbao wrote:
Sat May 29, 2021 4:39 am
and the image contrast looks way better on the cycle one. i was wondering if its the reason of tonemapping or color mangement?
what i did wrong on this? did i miss something while integrating the luxcore?
BlendLuxCore will apply some default image pipeline to map the tone similar to how Blender does it. Maybe your software is not doing that?
richardbao wrote:
Sat May 29, 2021 4:39 am
any suggestion would be appreciated!
I am not an expert with engine settings - maybe this will help, maybe I am talking nonsense :lol:

Also as CodeHD has mentioned, you did not specify how you setup your materials. It looks like some have too much bump (the table), others not enough (the walls). Perhaps there are some differences there also, that may affect how much light is reflected back into the scene.

The bedside table looks the same in both though - seems like you did something right there :)


Edit: when rendering from Blender, LuxCore will log out all the scene settings (e.g. image pipeline). You could also enable the File Exporter and inspect the other settings that are being exported (e.g. materials).
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Dade
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Re: Luxcore render result with blender cycle result? what i did wrong here?

Post by Dade » Sat May 29, 2021 10:36 am

Cycles image has more contrast because it is nearly a direct-light-only rendering while LuxCore image has some real global illumination: the difference is really huge. I assume Cycles has one indirect bounce at best.

You should also check the color spaces/tone mapping used for LuxCore rendering, in particular, you should be careful with gamma correction: it is easy to apply double gamma correction by not correctly declaring the gamma of input images (it will "wash out" the color of the rendering). Color spaces used can can also make a really huge difference in end result. sRGB color space:

Image

Same image with ACES color space:

Image

It may be better to compare HDR Vs HDR rendering to rule out tone mapping/etc.

LuxCore render looks also a bit too sharp, I would be curious to see the pixel filtering setting. If you post a test scene blender scene may be easier to say more on the subject.
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richardbao
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Re: Luxcore render result with blender cycle result? what i did wrong here?

Post by richardbao » Tue Jun 01, 2021 6:34 am

Thank you guys for the suggestions.
i will take a closer look at each of them.
it will take some time for me, and i will post feedback when i am avaliable.
have a good one guys~

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richardbao
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Re: Luxcore render result with blender cycle result? what i did wrong here?

Post by richardbao » Wed Aug 04, 2021 3:06 am

Dade wrote:
Sat May 29, 2021 10:36 am
Cycles image has more contrast because it is nearly a direct-light-only rendering while LuxCore image has some real global illumination: the difference is really huge. I assume Cycles has one indirect bounce at best.

You should also check the color spaces/tone mapping used for LuxCore rendering, in particular, you should be careful with gamma correction: it is easy to apply double gamma correction by not correctly declaring the gamma of input images (it will "wash out" the color of the rendering). Color spaces used can can also make a really huge difference in end result. sRGB color space:

Image

Same image with ACES color space:

Image

It may be better to compare HDR Vs HDR rendering to rule out tone mapping/etc.

LuxCore render looks also a bit too sharp, I would be curious to see the pixel filtering setting. If you post a test scene blender scene may be easier to say more on the subject.


Thanks for these info, a stupid question here, how can i apply ACES in luxcoreUI? or did you do that in other software?
will the OCIO support ACES and any info about this?

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Dade
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Re: Luxcore render result with blender cycle result? what i did wrong here?

Post by Dade » Wed Aug 04, 2021 9:12 am

richardbao wrote:
Wed Aug 04, 2021 3:06 am
how can i apply ACES in luxcoreUI? or did you do that in other software?
will the OCIO support ACES and any info about this?
The LuxCore support for OCIO is explained here: https://forums.luxcorerender.org/viewto ... f=5&t=3446

ACES is just a set configuration files for OCIO as explained in the link above.
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