which choose Normal map (Bump normal) or Displacement map for iray?
kitakoredaz
Posts: 3,526
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Post edited by kitakoredaz on
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I find a high rez mesh subdivision combined with a lower iray displacement subdiv works best. 16bit normalmaps also seem to give higher quality rather than 8bit jpegs, which is also true for displacement maps. There are lots of opinions about iray displacement, but if I want quality and better shading then I use displacement, combined with normalmaps for the extra fine detail, and for skin I'll also add a microskin tileable texture into the bump to add some glossy diffusion without relying on roughness maps. It takes longer to render, but you have to decide what level of realism you're willing to accept.
I'm not realy an expert, but I prefer displacement maps. There seem to be more controll options.
The important thing with 3DCoat is to note the displacement values that popup (one of the options outputs a text file as well) and use those as min and max values in the displacement settings. I use the displacement strength to modify the displacement scale to adjust for scale differences. If you don't use those 3DC values you'll probably end up with seams showing.
For normal exports, 'Maya/Max prior to 2012' works for me. I work with the DX version, and I think iray is OpenGL normals.
Iray will tend to create seams on displacement until/unless you increase the SubD in the surface settings almost to the subdivision level at which you sculpted. This makes it impractical to use displacement on human figures in many cases. I use normal maps for this reason.
Also, when dealing with normal maps, it's not a simple matter of overlaying something on top of what is already there. Normal maps use three colors to 'ecode' more information than a bump or displacement map.
There are programs that will correctly combine two normal maps...
AwesomeBump (newest version): https://github.com/kmkolasinski/AwesomeBump/releases
PixaFlux: http://gimpchat.com/viewtopic.php?f=22&t=13645&sid=9fb1d9aa4c919ededb1af2a52c84b723&start=10
and others.
I find the trick with iray displacement is to max out your mesh render SubD, rather than the iray displacement SubD (Mesh render Subd 4, iray 1, or 2 at most for face closeups). I also think that results in better displacement. I'm using displacement a lot these days, and the rig I do it on is years old with 12Gb of RAM and CPU rendering only, and once the shader build stage is finished it renders fine. I suspect the seams issue is possibly more ZBrush related and not keying in the displacement offset values for each UV group.
The major advantage 3Delight displacement has over iray's is probably adaptive sampling based on distance. As iray appears to essentially be a lovechild of Mental Ray, and Mental Ray has all the displacement bells and whistles you'd probably need, I suspect that won't be an issue with iray in the near future.
Whenever I intend to bake textures from one figure's mesh to another I initially export a figure in a pose that has the eyelids closed, the mouth open, and the legs, fingers and toes spread (this is for any 3D app, not just 3DCoat). For painting face textures I also have the eyelids closed and mouth open. If I'm painting on skin as a whole I only use the polygons that are the skin materials and hide the other parts for export (mouth, eyes, etc) - as long as the UVs don't change it doesn't matter what pose the figure is in. I don't sculpt in the voxel room (I have plans to soon) but use the paint room up until now. If you're baking or painting the mouth, etc, it's not a bad idea to move the eyeballs and mouth parts outside of the body (I think there are morphs on sharecg to help with this). For sculpting, I'd also suggest spending five minutes exporting the eyes, mouth, nails, etc, separately, and importing them separately into 3DCoat as surfaces that can be switched on and off as independent layers.
If you're sculpting, you can always merge the 3DCoat layers together before you do the bake. Even for paint, I tend to move all of the pieces of a wardobe so that they don't overlap or intersect (a suit of armour I painted up recently, for example), which gives better AO baking, etc.
I'll add that whenever I've been using a figure for a voxel base in 3DC (not for sculpting skin detail, but for clothing or accessories) I'll take the mesh into a 3D app and close the holes first. That gives me a closed mesh that imports properly as a voxel volume in 3DC, without the problem of fingernails closing across the width of the mesh, etc.
do not hide report from user!
Good stuff.