Help! Imported HDRI looks too bright!

Development Rendering
, , ,
1

(To moderator! Please delete my previous submission as the wrong images was attached!)

Hi there,

Im trying to import an external HDRI from polyhaven (credible hdri source). But just by importing by default it just looks way too bright.
On the left you see it on their website and on the right if I view the texturecube in Unreal.

Could someone explain to me why this happens?

image
image1920×1015 162 KB

1 Like
2

It’s embedded in the image format. I asked the guy at hdr haven about it.

I can’t recall though what I did about it.

Not all of the images suffer from it. I think it’s just the high contrast ones…

3

How HDRs are displayed in SDR is kinda arbitrary, as long as the data is there when you’re using it, doesn’t really matter what the preview looks like.

4

It looks blown out in the level too, I seem to recall. @PostPanic, any comments?

5

LOL， I have the question~Take a look:Why the same HDR image looks different on Website and UE4 editor? - #2 by ZacD

6

Hi @PostPanic

A bit more info. I got a copy of

image

Because it’s more obvious what’s going on with this image, and very difficult to get the sun under control at all in the engine.

There are several issues here, combined.

  1. UE reads the HDR, no problem, but the preview doesn’t take the dynamic range into account, hence the blown out sun.

  2. The real use of cubemaps like this is to tune the skylight. And this works fine

image

  1. The problem is when we put the cubemap on the inside of a sphere and try and use it as a background

image
image1221×786 30.4 KB

The engine has a plugin you can enable which sort of combines the skylight concept with a sky ball, but as you can see, the result is totally over exposed.

  1. The solution, as far as I’m concerned is this. Make an empty level and place just a sky sphere ( a mesh with normals pointing inwards in the level. You can place a very simple material on the sphere

image
image999×574 113 KB

But… this material doesn’t use the HDR, it uses the 8k tonemapped jpg that is also available from HDR haven. So far, still a little over exposed

image
image1326×763 43.3 KB

This is where the power node comes in, very good at tweaking this kind of thing. If we set the power to 1.25, add a skylight ( with the real cubemap on ), and a slight directional light, we get:

image
image1415×863 42.1 KB

So you’re getting all the benefits of the real use of the cubemap, without the blown-out look.

Hope that helps.

1 Like