This technology would be 1000x better if it would only enhance the drawing and not modify it!!! I draw buildings and want to apply backgrounds. It shouldn’t change the color of my buildings and add features I don’t want. Just add a beautiful scene!!! This issue makes it practically useless for me 
It’s not clear to me what specific technology you are referring to. Could you elaborate and perhaps share a model exhibiting the problem!
SketchUp 2017 doesn’t support Diffusion so it is impossible to know what you are talking about.
I believe he his talking about environments and the fact that it automatically turns the ‘photoreal’ materials on (unless you ask not to) : bringing reflection and therefore changing the color of his buildings.
@mattbuildings, you know you can keep the background on and disactivate photoreal ? Or also adjust material metalness
He uses SketchUp 2017.
Don’t trust profiles or dig into them, joined 2018, read 11m total…
His profile is the only clue we have.
And if that is true, he definitely isn’t using 2017!
yeah, my money is on Diffusion too.
Maybe pasting a picture on a large face acting as a background.
This face could be either a flat plane or a curved face or even part of a sphere.
Bon anniversaire ! 
All - I am using Sketchup 2024! Here’s two images to indicate the issues I’m experiencing. The first is the image in Sketchup, the second is after using Diffusion to help enhance the rendering. I simply typed add a background w/ cornfield. I’ve tried adding commands such as “do not alter the building” or “keep black siding and roofing” but nothing works. It always modifies the building in ways I do not want it to. I simply want the sky and background!!
I’ve had the same issue, but haven’t used Diffusion in a year.
My solution was to render 1 with diffusion, then render without the building on, then photoshop the 2 together. Difference being that I modeled my ground plane (on a hill).
Every time I rendered my building, it changed my model, adding random details that were not in the model. Hence the year gap.
This is the model with a raw SketchUp building and 5 minute Photoshop merge, cutting the building between foreground and background.
Prior to any Photoreal textures.
Diffusion isn’t(yet?) a realistic accurate rendering engine, it’s for early stages of a project probably to get some ideas but if you want an engine that renders all the geometry 100% as on the model and correct ray tracing for lights and shadows, you have tenths of options on the market, some are even free like Twinmotion and D5 or the industry standard V-Ray, there are a lot of options. I always recommend Brighter 3D if you don’t want to be tied to a subscription, it’s imo one of the best bang for the buck plugins for rendering, it cost $175 the perpetual license with lifetime free upgrades, I haven’t used it much cause I have a studio license that includes V-Ray, otherwise that would be my rendering tool together with Twinmotion.