Sculpting prop issues...And passing them to UE4

Larry

Hello guys so i have this container that i made. I made 2 versions, one that i want to import in UE4 and one that i wanted to import to Zbrush for sculpting.They have the exact same uv's, i just added some loops on the left one, to even out the topology, then turbosmoothed it with smoothing groups to get that to zbrush
But after some sculpting in zbrush, the form of the original mesh changed as well, even if i dropped it down to level 1, it has its basic shape changed. Do i need to export THAT model into 3ds max, and remove those loops again to get the sculpted mesh that i want?



In unreal i just used the normal map on a material and dropped that to the low poly that i had, and i think it only makes those gaps larger inbetween.No other detail is shown. This is the normal map i got from turbosmoothed object.

Can someone explain me what am i doing wrong?I have been trying stuff for alot of time, doesnt get me anywhere.Thanks in advance!

Scruples

I think you're handling this asset incorrectly, baking a completely unique normal map on an asset that large will get you rather low detail even with 4k textures. More traditional texturing methods will give you a better result so you should abandon this method for this particular piece.

Break the crate into several pieces and reuse each piece as much as possible without making it too obvious.

AlecMoody

Scruples is correct, that is too much unique space for a single texture sheet. You will want texture information that follows the corrugation and plate details (medium to small scale) but you also probably want some big details across the side to provide some large scale texture variation (ground fade dirt, logos...). The best way to accomplish that would be breaking the UVs out into tiling sections for smaller stuff and then using a vertex paint shader or decals for the big stuff.

Your approach of building a low and then subdividing it into a high is fine, so long as you don't expect to make any significant changes in zbrush.  With very few exceptions, you always want the low in your bake to be the same as the low in game.

Larry

@Scruples I want this container to be a main piece but will build a city out of these. It will have 2or 3 materials in it,plus a material for rust.I want to add variables on color and maybe rust alphas. Do I have to reuse the assets seperately? I was thinking of breaking it into 3 parts, the walls, the skeleton,and the metalic pieces, the screws will be floaters.

@AlecMoody this is the first time I hear about vertex paint shader. I will try and find information about it, but could you give me some insight?
I also noticed that you said that low+subdividing method is fine, do you mean that there other methods that you can sculpt an object?

Thank you both guys for the help!

AlecMoody

For props like this my workflow usually looks like this:
1. Build a medium resolution mesh where I can easily reduce the number of sides to make the low poly. For example, on something round I might use my target low poly number of sides and the turbo smooth with smoothing groups. This isn't to make even topology but just to add a lot of subdivisions for roundness.
2. Dynamesh master in zbrush to make even quads and nice control edge fillets.
3. Build the final low off of the medium poly mesh (not the sculpt) by removing turbo smooth, combining meshes where I want contiguous topology, and optimizing where needed.

Larry

@AlecMoody

i did as you suggested, i used 4 textures and exploded my model to build different normal maps, it worked out great.I used 1 texture for the side planes, 1 texture for the skeleton 1 texture for the doors and 1 texture for the metal bars+floaters.Now, i'm having issues on the shading in UE4. Does this have to do with the smoothing groups? I used smooth from UV's but this is what i got. Is this happening from smoothing or overlapping? 


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Obscura

This looks to be a lightmap issue in Unreal. You probably have overlappings on your lightmap uvs. Plus some gradients in the normal. That is because you baked with a one smoothing group setup. Or are you using smoothing groups from uvs? Then the reason for the gradients is that.

kanga

Make your highpoly however you like. Derive the lowpoly from the high or edit it so the there is no inter penetration with the high poly. Separate out overlapping parts like the thin bars by A/ exploding the mesh or B/ putting them in UDM space (seperate UV). There can be no interpenetration of the high poly model and the low. Bake.

I use a baking app like xnormal or substance painter so I don't have to load the high poly into anything once I have exported it from ZBrush. Then I import a decimated copy of the the high poly into max and use it as a template to build or edit my low poly on top of it to check everything is in the same space and that the high poly doesn't penetrate the low poly cage. I put everything in one smooth group on the low poly. With substance I haven't needed a projection cage yet. If you have exploded your model and all the parts have enough space for baking you should have success.

Larry

@Obscura I use smoothing groops from uvs. I know that this is free performance but should I also consider extra smoothing groups for optimised look? Or this does not have any difference atter I import it in a game engine? I also wasnt aware that I had to make different uvs for lightmaps, I learned that after your comment. Thank you! I have a question though. Do these uv islands work like nornal uvs in terms of performance? I mean, does the engine split the model and produce more vertices on the lightmaps uv channel? Or does this happen for texuring only? I am asking whether I should use a box unwarp or manually cut the whole model again for lightmaps, and if this will affect performance considerably.

@kanga I did everything you say except that my lowpoly and high poly were penetrating each other a little. Does my low poly have to cover the high poly entirely so that i cannot see the high poly? I am using xnormal and I have pumped up the distance a bit, I exploded the whole model in safe places too. The normal map seems okayish in 3ds.

Obscura

Yes it increases the vertex count. Lightmap uvs should be welded together wherever its possible. You usually get way better lightmap results when its like that anyways. However, I don't think that this would cause a real issue with a this simple mesh. If it would be some insane mesh with hundred thousands of tris then yeah it could.

musashidan

Look up the UE documentation.  There is a very helpful section on lightmapping. Unwrapping for texturing a d unwrapping for lightmaps are 2 very different concepts and require a different approach.

Larry

@musashidan I have, it is the one page I come across in every search I do. You mean this one right?
https://docs.unrealengine.com/latest/INT/Engine/Content/Types/StaticMeshes/LightmapUnwrapping/

While it does explain it decently, I cannot correlate to any of the examples it states since my mesh is somehow different from these ( or I lack experience to relate to any of these)

@Obscura well then I can copy the textured uvs and make sure the mirrored parts do not overlap? Will try that as soon as I get home!

Thanks guys for the info

Obscura

Yeah that should work. Good luck.

AlecMoody

Larry said:

@AlecMoody

i did as you suggested, i used 4 textures and exploded my model to build different normal maps, it worked out great.I used 1 texture for the side planes, 1 texture for the skeleton 1 texture for the doors and 1 texture for the metal bars+floaters.Now, i'm having issues on the shading in UE4. Does this have to do with the smoothing groups? I used smooth from UV's but this is what i got. Is this happening from smoothing or overlapping?


.

My suggestion was not to use multiple textures and unique map the whole shipping container. You should split it up into small areas you can re-use.

Larry

AlecMoody said:

Larry said:

@AlecMoody

i did as you suggested, i used 4 textures and exploded my model to build different normal maps, it worked out great.I used 1 texture for the side planes, 1 texture for the skeleton 1 texture for the doors and 1 texture for the metal bars+floaters.Now, i'm having issues on the shading in UE4. Does this have to do with the smoothing groups? I used smooth from UV's but this is what i got. Is this happening from smoothing or overlapping?


.

My suggestion was not to use multiple textures and unique map the whole shipping container. You should split it up into small areas you can re-use.

Well i will be using that same container alot of times in the scene. I cannot find any re-use of the items themselves in the scene that i want to recreate anyways. So basically i split the models textures into the sides,skeleton and metalic parts. They will all have their own material. I am mostly concerned of making this look good in unreal and that is my main goal for now, since its my first time using it