Why is the interactive result different from a render?

Corona Corona for 3ds Max Help Required
1

Ive been doing some work with a new building development and looking at how the sun casts through various areas throughout the day. The interactive rendering is great, i get nice shadows from the daylight system into the interior. however when i render its very diffused and i dont get those crisp edges anymore.
Any ideas?

Thanks
Jack

2

For some reason this fixed itself when i turned the daylight system off and on again

3

That’s strange. Are you using ambient occlusion in any scene material?

4

I dont believe so, its a straight revit > max with all materials converted to standard via Autodesk material converter.
It was kind of as if the sun was still casting light but it was not actually lighting the pixels on the floor.

5

Is there solid glass in the windows?

6

There is yeah. Corona Mtl Glass

7

So you are probably getting this:
“Reflections of light seen through solid glass may appear dark”
https://coronarenderer.freshdesk.com/support/solutions/articles/5000516180
Solution is to switch to thin glass, or use rayswitch.