I have it somewhere, but I'd have to look it up. So does anyone know the refraction number of thick see through glass, like a window?

Glass is generally 1.5. However, windows are usually given special treatment depending on the scene. You can get away with IOR somewhere between 1.4 and 1.6 for most glass objects, but windows can distort in strange ways depending on how they're modeled. Personally, if you don't want distortion for the glass on a window, you might just use the IOR for reflections only. This is known as "architectural glass". It depends on the scene.

Here's a small list of some values for different items:

https://blenderartists.org/t/material-ior-value-reference/365217

Here is a much more comprehensive list of all types of real-world materials and the IOR values for each. Might be a good one to bookmark.

https://pixelandpoly.com/ior.html

I just tried to explain in the Poser Forum why I was asking. I'm getting reflections depending on what angle the camera is aiming from.

Every type of surface aside from metal should have some degree of fresnel reflectivity, which is correct. So that's the proper behavior based on the IOR of the material. Looks fine in this render, assuming you mean the glass at the bottom of the produce case.

The back of the case is actually supposed to be a mirror. So it works fine. the two ends of the unit the divider pieces and the glass at the front of the case should all be see through. And yes, from the angle I rendered from, it does look fine.

EClark1894 posted at 10:06PM Sat, 02 May 2020 - #4387977

The back of the case is actually supposed to be a mirror. So it works fine. the two ends of the unit the divider pieces and the glass at the front of the case should all be see through. And yes, from the angle I rendered from, it does look fine.

Yes, the glass in the front of the case looks good from this angle. I didn't realize there was a mirror behind the produce. May I make one minor suggestion for later on? When it comes to planar reflections, perfect mirrors can look "wrong" or strange when the surface is absolutely flat and perfectly mirrored. In real life, most mirrors will have some sort of imperfections on the surface. Smudges, streaks, fingerprints, or even some bumps on the surface all lend to how our eyes and brains register the appearance of mirrors in real life. In the case of the mirror behind the produce case, it may be prudent to include some small imperfections in the reflection of the mirror. Adding a reflection map with some streaks or smudges is one way to really enhance realism on planar mirror surfaces. Just a thought for when you wrap up the texturing and are looking to add more details.

Like @LuxXeon said, something to liven up the reflection would be good. Often those kind of cases have misters, could add some water droplets or fog to the mirror surface. Maybe a little size variance in some of the items [green bell peppers I'm looking at you] would help as well. Looking good tho!

Also, check your ray recursion limit, I'm not sure I'm seeing the glass from the front of the case, in the reflection in the mirror?

another thought to help people see it's a mirror is having a seam. larger pieces of mirror or glass are more expensive and harder to work with so they use smalle ones.

Warlock279 and RedPhantom have some really good ideas there. I agree with those. If you need some help setting up some of those ideas, let us know. I have some custom reflection maps I've used for metals and glass that might help. If you add a few loop cuts into the mirror plane, you could bevel those loop cuts to make it look like seams from multiple pieces as RedPhantom suggested.

Also, as Warlock279 has mentioned, I don't seem to see the reflection of the front case glass in the mirror either. I thought maybe it was an issue with single-sided geometry or materials not showing up on the reverse side in reflections, but all tests I've done indicate that it shouldn't matter. So it's probably ray distance or bounces limitation causing that behavior, but it could also be caused by other issues like object-based ray visibility or even a light path node in the material setup.