Distortion in highly reflective windows


#1

I have a lot of experience modeling in Maya but not so much on shading/rendering side. I am working on a series of images that will include contemporary high-rise buildings with highly reflective windows. I am particularly interested in how the reflections are distorted by each window. I have attached reference images that I will be working from which should give you a sense of what I am talking about. In my source images, you can see how each individual window warps the reflection in a unique way. I am wondering if anyone can point me to information for how to approach this? As far as I can figure, there are two basic ways to do this. 1) find a shader that will warp the reflection differently for each pane of glass on the buildings. 2) do a render pass just for the windows and composite in a sky image. For the first approach, this seems like it may be very processor intensive and put a lot of extra geometry (i.e. extra work) into the scene to create the reflected image. For the second option, I am not sure how I would get the comped reflection to warp differently for each individual windowpane. I am expecting to use Arnold for this but can go with something else if you it makes sense.


#2

It’s easier than you think.

UV map each pane and shuffle the positions of each pane’s uv’s randomly up, down, side to side etc.

Then just apply a bump with a Brownian node to that surface along with the glass properties .

I used this before and its surprisingly effective.

Hope that helps,
Pete


#3

Yep, just use a randomized bump map on your window’s glass shader, with a large and smooth filtering so it’s not harsh and, you know, bumpy. You just want a bit of warp. This texture could be procedural (fractal) or it could be a simply tileable one, but you want it smooth and not gritty or noisy, and also a very low bump “value”, maybe around .05 but start at .1 or so to see how that looks.

As hominid said, you can randomize your UVs to help break up any uniformity as well.

It’s not processor-intensive at all. Bump maps are one of the oldest and easiest elements of a render.