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Im following this tutorial by blender guru about archviz. Im at the point where he's making the room however after adding the environmental HDR texture and the window glass texture, there seem to be a few problems.

  1. even without the window glass texture, the HDR is far too dark compared to his, which seems odd because mine feels like it should be brighter if anything. I'm using this HDR

  2. my windows seem to refracting different parts of the HDR? I'm not sure what's happening or how to best describe it so I've attached an image.

Windows being weird

any suggestions for how I'd fix this? here's the file:

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There are a few things you can do, I always tend to work on objects created with ArchViz because there is a problem with the windows.

For the refraction:

The ArchViz windows are usually a single face connected with the window frame, which on the one hand is not so good because you have non-manifold geometry. The other thing is, the glass material has an IOR of 1.45 which is okay for glass, but since the window is single-faced the refraction works as if everything on the other side is inside a solid glass ball.

And apart from the refractions being incorrect, the difference in left and right window are because they are oriented differently. One window refracts as if the room was inside the solid glass ball, the other window sees the outside in a solid glass ball.

To change this you can either set the IOR to 1 (no refraction) which would get rid of the incorrect look, but is of course not as realistic as if there was refraction in the glass. So the other option would be to select the window and press Y to separate it from the frame. Then press E > .005 > LMB to extrude it 5 mm. Now you have glass with a thickness and the refraction is correct.

For the brightness:

First of all, I have had brighter HDRIs than this one, but nevertheless you also have to keep in mind, a real sun and sky are very, very bright. In real photography your camera needs longer exposure times (or a faster lens) to get the same brightness in a picture than on the outside on a sunny day.

Which means, you need to either set the Exposure to a value higher than 0 under Render Properties > Color Management (by the way, setting the Look to either Medium High Contrast or High Contrast is also better than None) or to compensate for this, set the Strength in the World to something higher than 1. Or you do both.

Taking pictures with a real camera inside a room with a window in the background usually results in the outside getting exposed correctly and the inside of the room is dark, or the room is bright enough and the outside is really overexposed. In your screenshot the outside looks exposed correctly, so it's normal that the inside is quite dark.

Another thing is, the windows of the room look as if located on the shadow side of the building, as the sun in the HDRI is in a different direction. When you rotate the Environment Texture of the world in the Shader Editor so that the sun shines into the windows, it already gets brighter in there.

And last but not least, in reality light bounces around many times whereas in Blender the bounces are limited to a certain, not too high amount so that rendering won't take forever. This also has an influence on the brightness inside the room, but I think it's negligible in this case.

Here are some example pictures for brightness comparison (the glass refraction is already corrected and I've set the Look to Medium High Contrast). On the top left is the render with the default settings, the Exposure is set to 0 and the Strength of the world HDRI is at 1. Top right I just increased the world strength to 10. Bottom left strength is 1, but exposure is 3. Bottom right finally has an exposure of 2 and the world strength is 2 as well - it's almost identical to the one left to it.

shadow side

But as I said before, you also have to keep in mind that here the windows look outside on to a shadowy part. If you rotate the Environment Texture by 260° on the Z axis, the sun shines inside the room and even with the default exposure and world strength it's already much brighter, not to mention the other settings:

sunny side

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    $\begingroup$ Thank you very much! I'm still new to blender so some things confuse me but this really cleared it up! Thanks again $\endgroup$ Aug 12, 2022 at 7:55

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