Best projection mapping workflow?

Rukey

Hello,

I've always had a big problem with trying to project high sculpted detail onto a low resolution mesh, maybe because I am missing a crucial step. I wondered if anyone could give some tips or a suggested workflow for getting the best results possible.

I will lay out an example here (Simple broken concrete pillar):

1). So I started out with a low poly base with sharp edges so they wouldn't smooth out in zbrush. Also UV mapped because I planned on polypainting this as a test.



2). Imported the model into zbrush and sculpted some basic wear and tear for the look of the concrete.



3). I slightly decimated the pillar from zbrush and merged it into the max scene with the low initial mesh.

4). I put the two objects inside one another, at 0,0,0.

5). Press "0" on the keyboard to bring up the projection mapping options. Picking the high poly mesh as a projection. Choose existing channels. Add a normals map of about 1024x1024. Then proceeding to the modifier panel and adjusting the cage to fit around both objects.

6). Then choosing to render the normal map.



I think my major issue here, is the red areas of error maybe due to the original mesh not being big enough? Although does it seem that this normal map needs inverting?

So... That is the process I normally go through, yet I don't seem to get a very good normal map. Is it a case that I need to add more edges to the centre of the low poly object and/or retop the entire mesh? I only stayed away from retopping is about the mesh isn't changed to such I degree that I thought it would need it so.

Thanks for any help!

Scruples

Hard to say without seeing the final result, you could try making sure the highpoly is all hard edges when imported into max, decimation master and a single smoothing group don't really work well together.

SsSandu_C

Well... I think that that red areas you see are due to the fact that your low poly doesn't match very well the hp on the edges. As you can see you hp has imperfections on the edges and they are not straight where as you lp is just a rectangular box from what I see. It would be best if you cut the edges of the lp so it matches big areas of difference betweent them. And what global supersampler are you using? You might want to choose maxstar 2.5 or Hammsersley at 1 quality to get more details in your normal map. It will take a while longer than the default one but I think it is worth it.

tristamus

Your base should have had equally spaced quads all along it, and not the extra edges that you have there on each corner. You should consider using the crease function, in Maya or elsewhere (It's also available in ZBrush), to make all those edges that you needed to stay hard, hard, when you subdivided in ZBrush.

Also, harden all UV shell border edges.

Ace-Angel

Reset XForm, reset pivot, reset normals, make sure it has an Edit Mesh mod ontop of it, and lastly make your your last Projection modifier is actually active.

Next, harden the UV shells (Textools and Turbotools both have this function) to Smoothing Groups. UV islands = SG, also make sure you support loops are reading correctly.

Next, make sure you're selecting the proper channels in the baker, etc.

As for if the model is big enough, generally this isn't an issue if the model can be seen in the grid well enough and you have resented your XForm,

Hang10

adding to what Ace said above, try chamfering the edges so you can better capture the edges of the HP

EarthQuake

How does the normal map look applied to the lowpoly in the viewport? The normal map looks perfectly fine to me here, you're seeing various colors because thats what a normal map does, uses various colors to represent different angles, bevels along edges will produce some extreme angles, and thus extreme colors.

In addition to that you've got pixel padding which stretches the pixels out(to help with mip mapping) this looks weird but is in no way a bad thing.

So yeah, what does it actually look like in 3d, impossible to "debug" a normal map by looking at the 2d image.