High Poly to Low Poly workflow questions

jackanimated

Hi all,

I've recently started making low poly assets with the aim to get them working in unreal. I start with a high poly model and have some questions about the best workflow/order of practices of when to make the object low poly.

Before I do any baking to normal maps, should I make the basic shape of the object lower poly, getting rid of unnecessary quads, but leaving intricate details on certain areas to bake down? Then just remove the detailed geometry after.

At which point should I unwrap the UV?



Cheers.

mobpapst

the normal workflow is this:

1. make the hp model (normally all quads)
2. make the lp model (you just need the geometry to keep the silhouette and the shape)
3. unwrap the lp model
4. baking
5. texturing

jackanimated

So you bake from the low poly?

C86G

The baking process transfers information from the highpoly onto the lowpoly.

mobpapst

your high poly model is just a piece of information for your low poly. all you take from the hp are the baking maps like normal/ao/curvature etc.

jackanimated

But don't I have to unwrap the high poly first for the maps to bake properly?

mobpapst

you only need an unwrap of your lowpoly. you take later on your highpoly and your unwrapped lowpoly and bake maps out of it

jackanimated

I think what I'm getting confused about here is this:

I will bake from the hp which has different geomentry than the lp, so will the baked map fit the lp?

If so, then doesn't the hp need to be unwrapped in the same way as the low poly before baking?

mobpapst

i was up to write you the whole stuff to understand what its about. but if you are interested send me a pm with your skype account and i will add you and help you understanding what you need to know

Meteora

The high polygonal mesh does not need to be unwrapped. Only the low poly mesh needs it, because we bake the high poly onto the low poly. Think of the high polygonal mesh as a stamp that wraps itself around the low mesh.

WarrenM

1. make the hp model (normally all quads)

No, no, no. If it smooths correctly, it's fine. Quads are an option, not a requirement.

mobpapst

No, no, no. If it smooths correctly, it's fine. Quads are an option, not a requirement.

he seams to be new in this kind of work as you can mention. so it would be the best to start by looking for quads all over at the start. telling him to have ngons at flat surfaces would be the wrong start

WarrenM

Why? There's nothing wrong with that practice and obsessing over "all quads" is a time wasting habit I've watched too many artists fall into.

jackanimated

Wow, thanks for all the information. I'm going to follow some tutorials with some greater understanding now.

One last question I had:

When I made a lp version of a hp piece I made previously, I removed edge loops to simplify the shape rather than remodelling the whole thing. Is this a good way to make something lp as well?

Fansub

When I made a lp version of a hp piece I made previously, I removed edge loops to simplify the shape rather than remodelling the whole thing. Is this a good way to make something lp as well?

Yep,you can also remove additional edge loops to reduce polycount.

1. make the hp model (normally all quads)

In what universe is this still a thing ? Quad,tris or Ngons are perfectly fine no matter how n00b you are.I would suggest the author to take a look at this topology guide blog

jackanimated

Cool. Do I need to unwrap the hp model if I am applying a displacement map to it?

Fansub

Cool. Do I need to unwrap the hp model if I am applying a displacement map to it?

Why do you need to apply a displacement map on your high poly ?

If you want to texture your high poly for later presentation you can either unwrap it and texture it the classic way or use procedural textures with projected details.

Texturing a high poly can be a really complex task and i would suggest you to first start with the low poly,and once you understand how it works it will be easier to work with high poly textures.

jackanimated

I am going to bake the displacement map into a normal map.

jackanimated

A question about baking normal maps:

Does it make any difference to the outputted normal map, how reflective the currently applied material on the hi poly object I am baking from is?

Musetatron

No, normal map baker just read geometry information.

jackanimated

Ok, so here is my first atempt at normal mapping from a high poly object. Its an old leather chair.

Here is the exploded high poly:


Here is the lo poly:


Here is the normal bake from the hi poly:



And here is it applied to the lo poly:



It's not quite what I was expecting. And I notice that the bake on the cushions seems to look really lo poly. Any tips to make this get better results?

Does the hi poly have to be bigger than the lo poly in order to successfully bake from it?

Scruples

soften the edges on your lowpoly before baking.

jackanimated

Isn't the baking just taking data from the hi poly though?

WarrenM

Smooth out the low poly. Put it all into 1 smoothing group. You don't have any hard edges anyway ...

jackanimated

ok. Thanks for the introduction to smoothing groups. That has helped a lot.

jackanimated

Does the hi poly model have to be bigger than the lo poly model (meaning the hi completely encases the lo) in order to successfully bake from it?

cupsster

No, it doesn't, most important thing in baking is proper setup of cage, smoothing groups and eventually blockers if you are using xNormal for bakes. "Cage" enables you to control where ray tracing algorithm starts search so you can avoid geometry intersections and by using that cage encompass geometry that is protruding from LP mesh or floating geometry.

EDIT:
Actual surface of LP is not take into account when baking. It's normals yes. They control direction of incoming bake rays. So you can have HP mesh larger than LP. Important is to ensure that LP is following surfaces of HP as close as it could. They can intersect on many places.

jackanimated

Not sure I understood everything, but here are some examples:

This is with lo and hi poly together (low in pink).


here with the cage.


and here is that section in the baked normal map.


To me it looks like the protruding low poly is getting baked too. When setting up the projection, I select PICK and select only high poly objects.

Any thoughts?

cupsster

This is common issue if you bake in Max. Go to subobject level and select all faces then click Hide, then bake. If you want to avoid this just use xNormal man it is free and have exporter for max as well. It will save you ton of time.

WarrenM

Does the high poly have UVs? Maybe delete them? This messes up MODO, not sure how Max feels about it ...

jackanimated

cupsster wrote: »

This is common issue if you bake in Max. Go to subobject level and select all faces then click Hide, then bake.

So under projection mapping in the baking options I see a tick box for sub-object level. Do you just mean untick this? I cannot see any hide option.

cupsster

NO in modifier stack select your edit poly, select all faces and click hide. Should do the trick. There are other options how to do this for sure as well.

cupsster

I would suggest you REALLY look into xNormal

laforced

Apply a transparent material to the low poly. This works well
if you plan to do a full map bake and use white material for the
high poly in that case.

EdHanley

If you haven't already, then I would definitely have a good read of the wiki on Normal Maps here -> http://wiki.polycount.com/wiki/Normal_Map_Modeling

I agree with Warren on the high poly having triangles, its a waste of time removing them if i smooths correctly.

Ed

jackanimated

Brilliant. Went with a temp transparent material. Works a treat. Had a read of the wiki too.

Thanks so much everyone for the help. Through this thread I've gone from being utterly confused about workflow for game assets, to having a decent workable method. Educational. You guys rock!

jackanimated

Ok, this is not over!

Hi all,

I am baking a normal from a new model. I have made the LP transparent like discussed before, gave the HP a white and non reflective material.

Here is a bake. What are the white patches with straight edges on the underside of my mattress?

Also the red areas, I've expanded the cages enough and still getting red areas. I see some of the red is speckled or motled, that is not even on the HP model.

Any help please. I am lost now.

jackanimated

Help greatly appreciated.