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dpadam450

IBL Diffuse wrong color

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https://tse3.mm.bing.net/th?id=OIP.fCJwPm8kAFQIdWH9AZ7lWQEsDI&pid=15.1&P=0&w=251&h=168

First, I'm using standard RGB8 textures for my skybox, not HDR.  If I use a skybox with an image like above, downsampling it simply gives me a blue tint down my mip map chain. For PBR rougher surfaces, they all just look blue tinted when they shouldn't be.

I was thinking maybe this was because of using LDR textures where the brighter pixels would spread further, and thus making the downsamples brighter.  I would think that the clouds wouldn't be so bright to overcome downsampling more to white even as HDR, but maybe that is wrong. Even in a very cloudy day with minimal sun and blue sky, I would think even with HDR that it would just downsample to blue, but it depends on how many bright pixels are clustered and how high their range is.

 

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This doesn't really answer your question, but just wondering, do you really need mipmaps for the skybox? isn't it always going to be the same distance from the camera?

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I can support HDR in my engine, but at the asset level, I dont support HDR textures. So yes at some point I need to support loading in my skies specifically as HDR (no other specific asset in games other than potentially an emissive channel can I think would need HDR).

HDR and PBR are completely separate things. PBR is how light interacts and bounces. HDR is in respect to capturing a proper range of light/photons. So no HDR is not a requirement of PBR.

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Your intuition is correct: with true HDR sky intensities it's possible that the lower mip levels could have a very different result. It depends on the relative intensities between the clear pixels and the cloud pixels, which can  very different in a tone-mapped LDR image vs. an HDR image that uses values that are directly proportional to physical intensities.

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On 23/06/2017 at 11:01 PM, dpadam450 said:

HDR and PBR are completely separate things.

 

It's hard to tell that since you cannot represent any physically accurate lights without getting rid of the [0..1] limitations.

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