Windows reflections issue ///my 1st request for help///

Hello !
I’ve been struggling for years to fix my reflections in every glass or water material I create, which leads me to post my first request for help.
Basically, I’d like to have a simple glass material and be able to control the amount of transparency / reflection. But I always ended up with weird reflections, while having tried many nodes setup and spent a crazy amount of time on the internet to figure out the issue.
As you can see, the reflection are fine with a close view, but they don’t scale as you move away from the windows (on the main view it looks crap because the reflections appear too big thus blurry).
Faces are correctly oriented. The glazing is made of two faces. I wonder if there is something wrong with the IOR in my blender, cause when I use a node setup with IOR, I got weird results.
Here’s a link towards a few screenshots (can’t share them here)

Thanks a lot for your help, I’ve been using blender for a while now but I could never fix this.

Welcome :tada:

I’m not sure what exactly you mean with weird refections… also you do not use a glass shader so there is no IOR and when then it should be the IOR of… glass … also you seems to have already using some alternative like so:

and tweaked it with a RGB curve (which should be a float curve because it’s not R, G, B ??) :person_shrugging:

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You’re not using any IOR. For that, use Refraction shader instead of Transparency, and a Fresnel node, both using the same IOR. You can safely use Transparency for single sided window panes and water, unless you want the light to actually bend. For glass used this way, I use Layer Weight/Facing → Power 4 → Add 0.04 clamped. That is close enough to fresnel of real glass that nobody will know the difference, and you don’t have to worry about backfacing faces.

To control reflections like faking a polarizing filter, I just use some kind of Layer Weight/Facing with a curve to drive the Glossy color. At grazing angles it should still be pretty reflective. While not exactly accurate, you might be able to get away with simply reducing the Glossy color directly.


Thank you. Do you suggest a node setup like this ? I found it gives less range of action when you want to increase or decrease the strength of the reflections. if not, maybe you could share a sreenshot ?

Also, my issue is more about the scale of the reflections themselves : when the camera is close to the windows, it looks ok, but at a farer distance, the reflections look too big, causing the .PNG that I use as a backdrop to look blurry (see below).

close view

zoomed out

thanks, which set up would you suggest ?

my issue regards the scale of the reflections : they appear too large when looked at a far distance from the glazing. Because they look too large, they look blurry too (reflections come from PNG that I placed behind the camera, which have a given resolution and will looked blurry if zoomed too much).

I might no understand…

…usually when you are a looking via a mirror like object from far away the angle of view via this mirror is narrow and when comming closer more wide so you see more from the mirrored environment when comping closer…

Then… this might somehow be a problem with you world shader setup ?? Or somehow the proportion of the PNG in the back ground ???

You may have to elaborate this to get a more suited answer.

thanks for your answer, you are probably right!

If you make a building-sized reflector and check it out, you can see what’s wrong.

If HDRI is used for external environments, HDRI and modeling do not fit perfectly. (In most cases, there is no problem if it does not fit.)
In this case, adjust the HDRI to the appropriate size and angle.

Well, in that one you have Layer Weight blend set at 1, so it’s gonna max out no matter what. Here is (simplified) what I use for windows created by single sided rectangles.

I don’t have to do external views for what I do, but adjust the blue colored nodes to control reflectivity when watched from the outside (back faces). Random per island → Object Space Normal Map gives the impression that windows are not perfectly mounted, but 0.02 is too high for illustration.

For thin windows, you have to use Geometry/Incoming as the normal for the refraction shader. But due to opaque shadows, I just go with Transparency shader instead.

thanks for the screenshot man ! i never saw a setup like that before. I just don’t understand the purpose of the 2 combine color in backfacing.
I tried it with double faced glazing and it looks fine too.
My only issue is that every relfection looks weirdly too large, but i can cheat that by moving the reflected objects away in the background.

yeah i noticed that if i use an HDRI for the relfections, i get the same issue : HDRI looks huge in the glass and very blurry even if it’s high res

It’s just for control if you want it; one max reflection for the outside, and one for the inside. Guess the same could be done to the power; one power curve for the inside and one for the outside. Maybe for faking anti reflection coating or something.


I think I understood your problem.

In the examples of your posts #5 & 6, you make screenshots of your “3D View” in “Rendered” mode and you zoom in and out but “through” your camera view, therefore the position reference for the HDRI is the camera.

To get what you want, you need to move your camera closer or further away and the HDRI reflection will be adapted depending on the situation.

Tell me if it’s not clear …

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I just checked, zooming in and out in 3D view makes the same results as moving the camera closer or further away

I specify/clarify my previous answer :

In your 3D view, you must put yourself in camera view (numpad 0) and align your “Background Panorama” shot to your scene (you certainly know this).
Any other camera or each change of angle of view that you make, shifts you from the “fixed perspective” of your “Background Panorama” implying certain distortions/inconsistencies.

After rechecking, I correct that your posts #5 & 6 are in fact in “User Perspective” therefore (distortion/inconsistency).

In pictures :

1.- By moving the camera away or closer,
The alignment of the reflection will be preserved but the field will be narrower (further) or wider (clother) :

2.- By zooming in or out, in “Camera Perspective”,
The reflection remains “blocked” and remains the same size :

3.- Finally, in “User Perspective”,
It looks similar (depending on your movement precision), but it’s not the same result as 1.
you lose alignment and
the field will vary depending on your distance from the reflection (in the same
way as 1) :

Concerning the image that I use as a “background”, it is in 800 x 292 format (300ppi), it is mapped on a 2.74 x 1.0 m plan enlarged 8x (21.9 x 8.0 m).
On my images I notice a loss of quality when I only have a few samples !

Let me know if I need to correct anything…

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thanks for the very detailed answer :slight_smile: I’m usually only working on a singular camera view

Also, the reflections of the windows in the water is wrong. Does anyone have an idea of how to fix that or why that’s occuring ?