Glass in cycles vs light source behind it

Hi!

I’m learning ropes when it comes to rendering, I’ve never done it before (like actually wanted to give it a proper try).

One thing I got stuck on is currently glass having this very hard transition of with light source radius. I’m not sure what’s going on here and I could really use some advice.

Maybe I’m just using wrong set up for see through glass? I’ve tried several combinations of shaders and this is the closest one to what I want. Which is nothing fancy, just being about to look through the glass of a vehicle outside, while still being able to register there’s a relatively thin layer of glass between the camera and the exterior. I’m ok with some compromises in this area, as long as it doesn’t terribly distort the outside view.

I tried boosting up light bounces in all areas, that didn’t do anything.

The vehicle interior in question currently has 2 layers of glass.

One light point outside, close to cubes and other inside the interior, above the steering wheel

Looking forward to read your responses!

glass_test.blend (3.9 MB)

Side note, it looks reasonable from the outside to the inside (different scene, same problem)

Aaah, it seems that making radius of the source light fixes this for me.

I need to think of radius as a size of the light bulb. Which would also be mirrored as a very noticeable ball of light, in a way.

Here’s the light bulb size

import bpy

for o in bpy.data.objects:		# bpy.context.view_layer.objects:
    if o.type == "LIGHT" and not "Capsule" in o.name:
        o.data.shadow_soft_size = 0.1

If you turn off the multiple importance checkbox in the light’s settings you get rid of those harsh reflections of the light.

Multiple importance gives slightly faster rendering but creates those ugly circular reflections.

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