A question regardin Reflections and UVs

Hello, I was wondering if your models UV’s have an impact on the results that you would get from your reflections in your scene… and why?

For example; If I have a Wall with a material that is really reflective, a reflection capture sphere, with great lightmap-Unwrap but very poor ordinary Unwrap.

Does it affect the final result?

I say yes. If you have a bad unwrap, then you usually wouldn’t have a good lightmap since getting a good lightmap requires you to unrwrap it well. If you just unwrapped it once for say, the light map, UE4 would take that unwrap and unwrap it again in channel 1 (channel 0 if your texture map) and use that as the light map.

Let’s say you model something and don’t unwrap it at all because that’s the only way this scenario would work. You would get an auto-generated unwrap (channels 0 and 1) and you would get loads of UV overlaps, so the lighting and shading would not look good, thus even if you put a solid color on the model or a chrome material, you would see all the shading lines and it would look bad. SO with that being said, you need at least one good unwrap and roll the dice that UE4 will unwrap a second light map channel that looks good.

Hmm, alright! I think I understand. Well normally if I were to use a material with just a normal 3 Vector I skip unwrap on the “Channel 0” and only do an unwrap for “Channel 1 [My Lightmap]”.
I never let Unreal build my Light-maps since they doesn’t get close to what I create and I do get a very nice result when I build the lights for my scene. So as long as the Unwrap for the lightmap is correctly unwrapped everything is good?
Does the chrome create a third invisible channel for itself to contain the reflection values?

Oh and you may probably wonder to why I don’t just copy my good lightmap over to my messy first unwrap… Well there are no reasons for it actually… Sometimes I do it, sometimes I don’t, all depending on time.

I’m not sure what program you use, but copying and moving an unwrap to a new channel in 3ds max takes about 5 seconds. If you do a great unwrap on it and then let UE4 do the lightmap, it’s really not bad. I did it for every asset in my last build and it came out great. Even with more organic models.

There isn’t a secret channel for reflections. Reflections are built in the reflection map I think? Basically it’s stored in the reflection sphere or reflection box, whichever you’re using.

Oh okey! Thanks… I am actually using 3Ds max I just don’t bother with unwrapping the first channel!

The reason to why I manually create a lightmap is because I’ve had worse results by using it. Yet again thanks for the help sir!

Reflections won’t be changed by the UV’s. Reflections are made in two ways–reflection captures, and Screen Space Reflections, reflection captures are prerendered and SSR is a post process.
In the material, you can adjust the amount of reflection and the roughness which determines how the reflections appear on the material, the normal map changes the direction a surface is facing.

Now, that is what I thought! Thanks for clearing that up and helping me out!
Have a great day sir!