Eevee HDRI with low cubemap size sensitive to small rotations #66061

New Issue

rickietee10@gmail.com · 2019-06-23T21:54:36+02:00

2019-06-23 21:54:36 +02:00

System Information
Operating system: Windows 10 Pro Version 1803 OS build 17134.829
Graphics card: Titan x, gtx 1080, gtx 1060

Blender Version
Broken: 2.80, e7a0f0a993, master, 2018-6-23
Worked: (2.79, d39fb8ffbb2, Master, 2018-02-25)

When creating HDRi world nodes, they do not light the scene correctly. For example, I import env texture, add exr file and env shader, with a mapping node and co-ordinates node to rotate, when rotating, lighting drastically increases, and decreases. When tried in 2.79, the hdri lights the scene correctly,with no fluctuations to light output.

Have attempted in several builds of 2.80 and all create same problem. tested in 2.79b and no issues. Have canged colour space for env textures and still not addressing issue. made sure no light clamping enabled, made sure light bounces were the same across all tested versions, and cannot find the cause for these issues.

Exact steps for others to reproduce the error: Use attached blend in 2.80 and change the mapping node rotation value (Z) to 21 degrees, and you will see how lighting drastically changes. Append the world and model into 2.79 version and you you will see the lighting stays the same across the surface of the model, but the direction of the light changes correctly. Tested on all GPU's on their own, together and CPU also.

HDRI Issues .blend

**System Information** Operating system: Windows 10 Pro **Version** 1803 **OS build** 17134.829 Graphics card: **Titan x, gtx 1080, gtx 1060** **Blender Version** Broken: 2.80, e7a0f0a9934e, master, 2018-6-23 Worked: (2.79, d39fb8ffbb2, Master, 2018-02-25) **When creating HDRi world nodes, they do not light the scene correctly. For example, I import env texture, add exr file and env shader, with a mapping node and co-ordinates node to rotate, when rotating, lighting drastically increases, and decreases. When tried in 2.79, the hdri lights the scene correctly,with no fluctuations to light output.** **Have attempted in several builds of 2.80 and all create same problem. tested in 2.79b and no issues. Have canged colour space for env textures and still not addressing issue. made sure no light clamping enabled, made sure light bounces were the same across all tested versions, and cannot find the cause for these issues.** **Exact steps for others to reproduce the error:** Use attached blend in 2.80 and change the mapping node rotation value (Z) to 21 degrees, and you will see how lighting drastically changes. Append the world and model into 2.79 version and you you will see the lighting stays the same across the surface of the model, but the direction of the light changes correctly. Tested on all GPU's on their own, together and CPU also. [HDRI Issues .blend](https://archive.blender.org/developer/F7542029/HDRI_Issues_.blend)

rickietee10@gmail.com commented

2019-06-23 21:54:36 +02:00

Added subscriber: @Rickietee

Brecht Van Lommel commented

2019-06-24 14:20:16 +02:00

Added subscriber: @brecht

Clément Foucault was assigned by Brecht Van Lommel

2019-06-24 14:20:16 +02:00

Brecht Van Lommel commented

2019-06-24 14:20:16 +02:00

This is an issue in Eevee which did not exist in 2.79.

Increasing Render properties > Indirrect lighting > Cubemap size avoids the issue, changing the filter quality does not.

This is an issue in Eevee which did not exist in 2.79. Increasing Render properties > Indirrect lighting > Cubemap size avoids the issue, changing the filter quality does not.

Brecht Van Lommel changed title from ~~HDRi Issues~~ to Eevee HDRI with low cubemap size sensitive to small rotations

2019-06-24 14:20:44 +02:00

Clément Foucault commented

2019-06-27 18:08:22 +02:00

Changed status from 'Open' to: 'Archived'

Clément Foucault closed this issue

2019-06-27 18:08:22 +02:00

Clément Foucault commented

2019-06-27 18:08:22 +02:00

Ok I know what is causing the problem. The issue is that Eevee renders the cubemap using a lower resolution than your HDRI. The HDRI contain very high frequency details that are strong enough to produce energy spikes. If the cubemap target is small, each texel of the cubemap has more solid angle than a single star and thus more lighting power. So if a small bright point gets rendered do a much bigger texel inside the cubemap its energy is multiplied.

This is a limitation of how eevee renders the cubemap. To fix it, we would have to super sample everything and do more or less the same thing as increasing the cubemap size.
But the main issue here is the really bright stars. You can dim them for diffuse using the light path node.

Maybe we should add a Clamp Diffuse parameter.

Ok I know what is causing the problem. The issue is that Eevee renders the cubemap using a lower resolution than your HDRI. The HDRI contain very high frequency details that are strong enough to produce energy spikes. If the cubemap target is small, each texel of the cubemap has more solid angle than a single star and thus more lighting power. So if a small bright point gets rendered do a much bigger texel inside the cubemap its energy is multiplied. This is a limitation of how eevee renders the cubemap. To fix it, we would have to super sample everything and do more or less the same thing as increasing the cubemap size. But the main issue here is the really bright stars. You can dim them for diffuse using the light path node. Maybe we should add a Clamp Diffuse parameter.

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Eevee HDRI with low cubemap size sensitive to small rotations #66061