Displacement Modifier Issues

Hi All,

With reference to thisthread some questions about using different file formats for displacement in blender. ZBrush exports 16bit tif displacement maps. Unfortunately blender reads these in as 8bit so loses detail. This results in the test mesh getting messed up if you sub-d it too much:

So I tried using photshop to convert the 16bit tif to a exr and the result shows a problem.

See subd 3 with tif displacement map, subd 4 with tif displacement map, and exr renders attached.

Someone using Cinema 4D had a similair problem, see here it is in his pic the one titled: “Displacement w/default intensity centred”

I may have missede other threads with attempts at this problem. Anybody know how to fix it?

A.vector

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mmm…I think the only way to fix it is to export a 32 bits tiff image from zbrush, and then convert it to Open EXR using cinepaint maybe, or photoshop. Always maintaining the 32 bits format, cause that is the only way to prevent that kind of banding.
Converting to different image depths can be a problem, cause luminosity is not handled the same way in an 8 bit image and in a 16 or 32 bits image. I´m no expert in this matter, but you may have noticed that 32 bits image doesn´t have a brightness option, they have exposure and gamma options. I think that is why your Open EXR displacement map rendered like that. So, my advice is to try exporting in 32 bits and converting the image to a 32 bits Open EXR.

On the other hand, and I hope this does not discourage you, Blender Internal engine does not support MicroPolygons displacement yet (though, there is a project about this and builds can be found at graphicall.org). So, to tell you the truth, you won´t be able to take advantage of the 20 million polygons that ZBrush can give you, instead, you can always use Blender´s MultiRes and bake your 32 bits Open EXR displacement maps. Depending on your machine, you will be able to subdivide your model up to 6 millions polygons and still be able to work well with the sculpt tool. This means that the only details you won´t be able to do with the MultiRes are the Pores of the character, but you will be able to do detailed wrinkles and all such small details. Pores have to be done separately with bump maps or normal maps. Normal maps can be baked in Zbrush and used in Blender in case you want to model the pores in ZBrush.

Here´s the reference page about displacement map baking in Blender:

http://www.blender.org/development/release-logs/blender-246/render-baking/

See the MidLevel setting in the displace modifier? move that untill you get the correct displacement

jpbouza: Thanks for all the info, really helped me figure this out! It seems like you are correct about the 16 32 conversion thing. To avoid it I used the displacement in zbrush to generate a high res mesh and then made a 32bit displacement map from zbrush. This is still a tiff so I used photoshop again to convert it to exr using zip16 compression. See attached image and zbrushcentral threadfor exact steps to create it.

I see your point about the detail levels, on another project I tried creating a displacement map from zbrush using the full level of detail and then creating a normal map for the last couple levels and that seems to work well with blender. It’s not quite finished but I’ll post a link to the results when it is :D. I prefer using zbrush to sculpt as I am used to the tool system. Another option is to import a 6 mil poly version from zbrush and bake the displacement in blender as 32bit exr and then create the normal map from that level of detail up in zbrush.

ZanQdo: I haven’t tried this as the other solution worked. I think that it won’t work as the banding comes from a lack of definition in the displacement map but I could be mistaken.

a.vector

ps the second image is also attached from zbrush thread
pps hereis the link to the other thread :slight_smile:

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