Question about High to Low Poly Baking Process?

ChromaWitch

I haven't done this yet. I'm trying to understand it. So please let me know where I am wrong and clarify.

From what I gather, you:
- Build a high poly model, then create a low poly model (from what I understand by modeling against the surface of the high poly, like with freeform modeling in 3ds Max).

- Unwrap the UVs for the low poly. Do you ever unwrap the high poly?

- You go into a program like Substance and bake the high poly into the low poly.

And I have a few questions to fill in holes. Some people from tutorials seem to have normal maps and such to plug into Substance before actually texturing. I believe they say you get it from the materials in the 3D program you use. In 3ds Max, how do you do this?

Do you HAVE to model High to Low, or is that a preference? Is it more preferred in professional studios? Can you do low to high? 

Barbiturat

- Unwrap the UVs for the low poly. Do you ever unwrap the high poly?

There is no need to do UVs for highpoly in most case.

And I have a few questions to fill in holes. Some people from tutorials seem to have normal maps and such to plug into Substance before actually texturing. I believe they say you get it from the materials in the 3D program you use. In 3ds Max, how do you do this?

What kind of Normal Maps do you mean? Microsurfaces ? Could you give more information or some example?

Do you HAVE to model High to Low, or is that a preference? Is it more preferred in professional studios? Can you do low to high? 

High to Low is more preferred in professional  studios, but it depends on pipelines. Some studios do Low first. 

EarthQuake

Low to high generally isn't practical. The reason for this is that it's common for things to change a bit during the high poly stage, which means your high will no longer match the low. Low to high tends to work best with very simple models, but falls apart with anything complex.

It's common practice to create a simplified blockout mesh to get proportions right before moving onto the high. This is not a high poly nor an optimized game ready low poly, but you might start from it for both the high and low. This is the preferred way to work for hard surface assets. Making a blockout means you can show it to whoever you're working for (boss, client) who can pass off on it before you get to a stage where making changes is more difficult.

For organic stuff, the high/design phase tends to be more loose, which again means low -> high is impractical. So you'll generally re-topologize when the high is done.