How do people use "Trim Sheets?"

Elarionus

I'm about to begin a big sci-fi project, and I've been reading up on a lot of Alex Senechal's works and blogs. He talks about these things called "Trim Sheets" a lot, which seem to just be flat planes with a ton of different details in them. They don't necessarily flow together though. It looks like it's just a collection of all of the details that he plans on using on a piece. I have folders of alphas and whatnot, and I was wondering, what exactly are these Trim Sheets, and how do people use them to modify their work? The main term I hear thrown around with it is modularity...where does that come into play? Thanks!

lockey1995

Commenting to wait for replies I need to know the same 

Eric Chadwick

Recently answered here 
https://polycount.com/discussion/comment/2667235/#Comment_2667235

Eric Chadwick

lockey1995, did you read Jacob's thread and still have questions? Happy to answer.

lockey1995

Eric Chadwick said:

lockey1995, did you read Jacob's thread and still have questions? Happy to answer.

Yes i did only one question i have he seemed to scale the mesh to the grid and had one texture for brick etc I'm not sure if he merges those materials into one sheet at the end. Surely you wouldn't have one texture for each piece I:e wood,metal,brick,rock etc if you get what I mean it's hard to explain 

Eric Chadwick

First, design your trim texture, so you have multiple textures inside one bitmap, all packed in next to each other.

Cut edges into the model, where you need UV seams.

UV a selection of polygons, scaling and moving the UVs to fit into specific parts of the texture.

Use a separate material for each texture layout. 

lockey1995

Ahh ok would this generally be used on certain props at all e.g. lets say a stair case that belongs in an environment or would that be the usual method like the one in my post and actually applying textures to the shells

Kanni3d

@lockey1995

The most optimal way would be trim sheets for a staircase, yes, since there is plenty of repeating elements. What you referred to in the first post, the sheet with tons of different details that don't flow together, is known as a decal sheet. Which can be used to just float details onto meshes.

Eric Chadwick

Two related options here:

Trim sheet = a bunch of textures laid out side-by-side inside one bitmap.

Decal sheet = same, except these are overlaid on top of another texture. Either via transparent edges, or buffered rendering (deferred rendering, stencil buffers, etc.).

Snweos

A Trim Sheet and a Texture Atlas are the same thing?

Elarionus

Eric Chadwick said:

First, design your trim texture, so you have multiple textures inside one bitmap, all packed in next to each other.

Cut edges into the model, where you need UV seams.

UV a selection of polygons, scaling and moving the UVs to fit into specific parts of the texture.

Use a separate material for each texture layout. 

So...based on the things I read in the wiki and from your post, the way trim sheets work is that you make the details first, cramming them all into one UV square, 2048 x 2048 or whatever resolution it is. Then you use that as a sort of "backdrop" while you're editing your UVs in 3DS Max, and you position the polygons where you need the detail over top of that detail? If that's the case, it clears up my main question, which involved what was the point of having those detailed squares...those are just visualizations of it.

On the other hand, it raises some new questions. If the trim sheet is only the size of one UV chunk, how do you make things big enough or small enough? Because of the size of trim sheets and the limits you have to fit things into them, do you make multiple trim sheets for different things? Like a trim sheet for floors, a trim sheet for walls, and a trim sheet for ceilings? Aside from the modularity of it, for the most part, you're still hand placing UV maps. Is it just to save space so that you don't need several hundred different texture maps?

And while I was typing that I thought of another one...if you have a trim sheet for a floor, and you have four separate patterns side by side on the trim sheet, you have to fit the floor polygons into one fourth of the UV space. Wouldn't that make it come through quite blurry?

All of these questions are assuming I'm understanding them correctly of course. And thanks for taking the time to explain it. Sometimes it's hard picking the gold info out of the old threads.

Eric Chadwick

Then you use that as a sort of "backdrop" while you're editing your UVs in 3DS Max, and you position the polygons where you need the detail over top of that detail?

Yes. You got it!

If the trim sheet is only the size of one UV chunk, how do you make things big enough or small enough?

Couple ways.

You can make the sub-texture tile left-to-right, or top-bottom. Then scale the UV strip of polygons outside the UV square to tile.

Another is to split polygons with new edges whenever you need to tile. Then stack the UV polygons inside the same sub-texture. Extreme example... floor is a giant plane, divided into a quad for each floor tile, all uvd to same sub-texture.

Another way is to use a shader to virtually split the sub-texture into individual tiled textures.

I'll try to answer more later.

Eric Chadwick

do you make multiple trim sheets for different things? Like a trim sheet for floors, a trim sheet for walls, and a trim sheet for ceilings? 

Yes. Generally, the more reuse the better.

Aside from the modularity of it, for the most part, you're still hand placing UV maps. Is it just to save space so that you don't need several hundred different texture maps?

Yes. Several savings here. Lower download/install size, lower memory use, faster loading, better framerate.

Wouldn't that make it come through quite blurry?

If a single tiling texture is 512x512, but you pack four of them into a 1024x1024 trim sheet... that's the same resolution, but you're sending one texture to the GPU instead of four separate ones. 

The trade off is more art prep time, and more complex shaders. But depends on the situation. Each game accepts different tradeoffs to weigh its unique goals.

Sometimes it's hard picking the gold info out of the old threads. 

Counter intuitive here, but the best way to learn is to struggle through it yourself, rather than trying to get all the gold via others.

Yes we stand on the shoulders of giants, etc. However, you must exercise caution not to take these things as "ultimate truth" , including my posts too haha.

Research, test, fail, question, ponder... repeat. This is the path to sure knowledge. And it's a blast! Learning is the best part of my day.

Eric Chadwick

Some relevant links 

https://api.unrealengine.com/udk/Three/TerrainAdvancedTextures.html#Texture Packing: Implementing large texture tile sets

http://poopinmymouth.com/tutorials/thirding-textures-tip.html

https://www.chrisalbeluhn.com/ut3-adding-variation-to-a-repeating-texture-pattern

http://www.philipk.net/tutorials/modular_sets/modular_sets.html

lockey1995

This is great will be looking through all of these

lockey1995

Eric Chadwick said:

Some relevant links 

https://api.unrealengine.com/udk/Three/TerrainAdvancedTextures.html#Texture Packing: Implementing large texture tile sets

http://poopinmymouth.com/tutorials/thirding-textures-tip.html

https://www.chrisalbeluhn.com/ut3-adding-variation-to-a-repeating-texture-pattern

http://www.philipk.net/tutorials/modular_sets/modular_sets.html

Only thing is i wanted to know when you're doing the above method and moving your uvs to the trim sheet what about texel density between meshes does it still need to match?

lockey1995

Kanni3d said:

@lockey1995

The most optimal way would be trim sheets for a staircase, yes, since there is plenty of repeating elements. What you referred to in the first post, the sheet with tons of different details that don't flow together, is known as a decal sheet. Which can be used to just float details onto meshes.

So generally anything that tiles allot I e the staircase i mentioned etc literally pretty much benefits from this method then and it's the way to go about doing it ?

musashidan

Why don't you just buy Alex's Gumroad tutorial where he explains his trim sheet workflow in-depth?

lockey1995

musashidan said:

Why don't you just buy Alex's Gumroad tutorial where he explains his trim sheet workflow in-depth?

I'll look into it might be the best thing to do link?

Eric Chadwick

lockey1995 said:

I'll look into it might be the best thing to do link?

https://www.google.com/search?q=alex+trim+sheet+gumroad

lockey1995

I will be buying that 

lockey1995

Eric Chadwick said:

lockey1995 said:

I'll look into it might be the best thing to do link?

https://www.google.com/search?q=alex+trim+sheet+gumroad

Anyhow I did a basic house design and had some practice set up a 2048x2048 texture and did a 1024x1024 for each a brick texture and a roof have I done this correctly or not here's my uv's. Only thing i was curious about was texel density when working with these trim textures I made it equal there.

Eric Chadwick

Yep, it's a start!

Once you get through his tutorial, you'll see how versatile it really is, and how to visualize the process. It's quite fascinating. Lots of techniques to explore.

lockey1995

Eric Chadwick said:

Yep, it's a start!

Once you get through his tutorial, you'll see how versatile it really is, and how to visualize the process. It's quite fascinating. Lots of techniques to explore.

I have started watching it and I'm starting to understand a bit better now so when would you go for a unique unwrap opposed to this method? maybe something like a dumpster or something here is my next piece i need to texture not sure whether to go unique on this or just do the above. It will have 4 materials a metal floor, the railings, steps and the stair railings are actually wood in real life. I'm just confused on when to approach each one need some clarification.

Eric Chadwick

When you need something unique!

Also, "hero" assets are usually uniquely textured.

lockey1995

Eric Chadwick said:

When you need something unique!

Also, "hero" assets are usually uniquely textured.

I might need to then on that one because I did want to add weathering to the railings etc 

lockey1995

Eric Chadwick said:

When you need something unique!

Also, "hero" assets are usually uniquely textured.

Ok one more since you've been an amazing help are they just textures thrown in or is it actual Geo baked down and uved and textured in substance etc. I know then you move the uvs to the texture and work it from there it's just the before bits that have me a little confused.

Eric Chadwick

Depends. Sometimes you create textures from geometry, sometimes from photos, sometimes procedurally (ala Substance), sometimes painted by hand. Depends!

lockey1995

Eric Chadwick said:

Depends. Sometimes you create textures from geometry, sometimes from photos, sometimes procedurally (ala Substance), sometimes painted by hand. Depends!

Many situations then I settled at the moment on creating my metal texture in substance exporting it to photoshop and setting it all up in photoshop the others like brick etc just doing from edited photos. 

JCarlosHorta

Interesting topic! But I have to ask. Isn't this method bad for texel density? If you scale UV shells at different sizes this could harm the TD. I mean, you are using tiling textures so this is probably unnecessary, but jet again if you see this post, TD is also used whit tiling textures. 

You can check this link to understand a little bit more about what I am saying. 

https://www.artstation.com/artwork/qbOqP

m4dcow

JCarlosHorta said:

Interesting topic! But I have to ask. Isn't this method bad for texel density? If you scale UV shells at different sizes this could harm the TD. I mean, you are using tiling textures so this is probably unnecessary, but jet again if you see this post, TD is also used whit tiling textures. 

You can check this link to understand a little bit more about what I am saying. 

https://www.artstation.com/artwork/qbOqP

Unless you are trying to apply wildly low or high res trims to an area, texture density shouldn't be much of an issue.
Typically the width of the piece of trim should match up roughly with your tiling texture when it comes to texel density. Sometimes you might have to stretch the trim UVs for things like round columns so there isn't a seam but even then it shouldn't be drastic.