How would I follow best practices with this model/reduce the poly count?

Rekov

I think I'm okay at modelling, but I don't really have a sense for the right and wrong way to do things, which is what I'm trying to figure out. I also don't have a good sense for what tris counts to shoot for.

This cannon I made has 12.6k tris, which strikes me as way too high (but I could be wrong?). I put supporting edges in most places which contributed to the high poly count, but I left the interiors of flat faces a jumbled mess of triangles, which I imagine is something better avoided. How should I approach this project differently? Where should I reduce the number of tris I'm using, and is there anywhere I might wish to increase it?

AtticusMars

The best solution would be to just remove your beveled edges from your lowpoly and let your normal map take care of it.

Rekov

AtticusMars said:

The best solution would be to just remove your beveled edges from your lowpoly and let your normal map take care of it.

This will be very easy to do, and what I would have done a couple months ago, probably. I read so much about how doing this can lead to distorted normal maps, but I don't think that will actually matter in this case since I'm not really baking detail like that down. Thank you. I will try that.

Do I need to worry about maintaining all quads at all, or should I just make it as cheaply as possible with a bunch of tris?


On a somewhat unrelated question, right now I have all of this on one sheet. Is this model complex enough that I should split it up, maybe with the cannon and metal bits on one sheet, the wood on another? It would obviously give me a lot more texels to work with.

AtticusMars

Rekov said:

This will be very easy to do, and what I would have done a couple months ago, probably. I read so much about how doing this can lead to distorted normal maps, but I don't think that will actually matter in this case since I'm not really baking detail like that down. Thank you. I will try that.

Depending on what you're doing you can get different results without support loops. If you are baking to a single smoothing group you may get distortion in details and strong gradients* in your normal map, you can alleviate this simply by using multiple smoothing groups and UVing them accordingly. There's more info in the stickies in this forum and also on the wiki.

*Gradients in normal maps are rarely a problem these days as most engines will have synced normals

Do I need to worry about maintaining all quads at all, or should I just make it as cheaply as possible with a bunch of tris?

Triangles are fine.

On a somewhat unrelated question, right now I have all of this on one sheet. Is this model complex enough that I should split it up, maybe with the cannon and metal bits on one sheet, the wood on another? It would obviously give me a lot more texels to work with.

One map is fine.

I wouldn't split up a texture map unless there was a logical reason to do so. A good example would be to break a characters body/eyes/hair off into multiple sheets as they will all be using different materials. Hair and eye materials can require special maps that it wouldn't make sense to waste on a whole body that doesn't use them.

Rekov

Thanks so much AtticusMars. I've managed to get the model down to 7.5k, which still strikes me as a little high but is at least a marked improvement.

I've tried my hand at using different smoothing groups before, but I've never liked the result because if you want to bake a rounded edge onto two different smoothing groups, you get a visible little seam there instead of a smooth curve.

AtticusMars

You should not have noticeable seams provided you separate your smoothing groups into separate UV islands with sufficient padding. See handplane's great video on this.

Rekov

I understand the concept and I've seen that video, but that just isn't how it works, unfortunately. The basic problem which my sketch below illustrates is that since rays project straight out if you have separate smoothing groups, the curved part of your high poly model gets detected twice.


This is a side on view of the intersection of two planes that are part of different shading groups. The colored arrows indicate the projected vectors for baking the normal of each group. As you can see, the area being circled in pink gets copied twice.

You can actually see exactly this happening in handplane's video. The cube bottom left was baked with separate shading groups, while the top right one wasn't. You can clearly see this duplication in the curve along the edges and especially the corner.

AtticusMars

Two things:

1) The issue you're illustrating is only a problem if you bake without an average projection cage, using a cage you won't get those seams because the cage will be used for raycasting. The tradeoff with this is distortion in your projection, but there are ways to deal with this.

2) You're mistaken regarding the video, both cubes are baked with separate smoothing groups. The only thing that differs is the UV layout, the one on the right uses separate islands each smoothing groups while the one on the left is UV'd with islands stitched into a cross. I'd suggest you rewatch that section of the video.

Edit: I linked the Handplane video primarily because I mentioned gradients, which is displayed at the end of the video where he shows what happens to the shading caused by gradients when the tangent space of the renderer doesn't match what was used to bake. It wasn't intended to be a solution to distortion, guess I should have clarified that.

Regardless, you asked earlier what the "best practice" was and like most things the answer is simply "it depends". The wiki/videos I linked cover the vast majority of use cases and offers suitable solutions for them. Sometimes gradients won't be a problem, sometimes distortion won't be a problem, when they are you'll have to determine for yourself what approach you can take to solve them and that could be anything from combining bakes, using support geometry, using a skew mesh, or simply applying your details during the texturing stage. There are a lot of ways to generate normals that are all perfectly acceptable and the only difference is the tradeoffs.

If you want to further reduce the triangle count you can get rid of a lot of these loops (maybe more, I can't really zoom in on this):



When allocating geometry your primary concern should be the silhouette, especially when it comes to cylindrical objects having loops that aren't doing anything to hold the silhouette pile on a ton of unnecessary geometry.