Sculpted Mesh - how to export/extract the bump?

Hi Guys,

I know the title looks a little naff, but couldnt think of any other way to put it.

Suppose you start with a cube, set the multires up high enough to sculpt fine detail - say level 7. Now one has a nice sculpted mesh - how would one get a bump map only [ .exr.hdr maybe ] of this mesh for use in other apps?

OR if one modelled in another app that has no sculpt features and wanted to export the mesh temporarily to Blender to Sculpt in new parts, then back to the first app and apply a generated ‘bump’ representation of what was done in Blender.

Any ideas?

I don’t think you can do this in Blender yet because Blender doesn’t create tangent normal maps at this point. You might be able to try the cavity shader technique described in this post ((courtesy of Conz3D)) to create something similar that can be used as a bump map though:

Hi Rambobaby,

I think we are into the realm of normal maps here no doubt and the use of XNormal etc I imagine?

I have just been having a go at Render Baking -

This might do the trick as one can get a normal OR a full render bake, then into a graphics app to make a greyscale or B&W image from it. BUT - I noticed if you have a mesh with Multires level set to 7 and UV unwrap it alls fine, now drop the level to say 4, Unwrap - now you get an unwrap different from the first in that the unwrapped parts are positioned differently in the UV / Image editor Window. This as you can imagine causes difficulties if one wanted to export a lower res mesh to load into another app and apply the baked bump.


I think that if you do a render pass using the Z buffer content, you will get a greyscale texture usable for Bump Mapping.

Hi Roubal,

This still does not discount the fact that if you try UV a mesh at one Multires level, then UV it at a higher level - the UV map/image is different for both. This is what I am finding at the moment.

Try it - start with the basic cube, add UV Seams first - then add 7 levels of Multres. Go back to level 4, UV Unwrap. Now go back to level 7, Unwrap. Notice both Unwrap images in the UV Editor window are different.


I’m not sure that I understand well your problem. Multires is used for the modelling stage. Once you’re happy of your model, I think that you have to Apply Multires (the same effect as making the modifier real) and then, you can create your seams and UV unwrap your model.
Do not create your seams on the low resolution mesh.
For my own, I almost never use the Multires tool, because Extruding is not possible in Multires mode, and because of that my worflow is slowed down. I don’t find this tool handy.
The creation of the bump map is an other part, and using the content of the Z buffer works fine to create a greyscale image. You have just to add a Map Value node to the Z buffer, because the value has to be scaled and an offset can also be needed to get the correcty contrast of the Black and white texture.
I have just tested it, andit works fine.

You can bake an AO map then pipe the result through an inverted color ramp in the nodes (the color values have to be reversed else your bump map will be inverted) and finally apply the result in the textures channels by seting map input to uv and setting map to to normal. This only sorta-kinda works though. It just looks a bit funky. Maybe you can get a better result than I can.
The problem with the depth buffer is that it will only give you a view dependent map. If you uv map an AO bake it will wrapp around the mesh properly but the normal result is kind of ugly if you don’t light the mesh correctly. Even when well lit it’s still kinda funky.

As far as your problem with unwraping is concerned; if you’re going for high res to low res then you need to apply the multires for the low res version so that you can select the individual verts and or faces of the uv map, then adjust the low res version to fit the high res version. It had better be fairly low res too, else you’ll have a bitch of a time matching everything up. You can’t move uv coordinates around with a multires level higher than 1 which means you have to apply the multires.

Hi Lads,

Thanks for that lot. I started with a cube - multires level up to 7. I then sculpted this into a sort of creature head. What I found was that I could lower the Multires to 4, UV map it and export it out to an OBJ. WHAT I was hoping to then do was push it back up to 7, commit the Multires, UV Unwrap it, add a blank new image AND THEN Render Bake say a normal or texture. Once this was done - open another app, load the level 4 mesh and apply the Higher res bump created from Level 7. Sounds like a reasonable workflow in my brain anyway :slight_smile:

OH, and if I go back to Multires 1 I will end up with a … yes you guessed … a cube …

Hopefully, Roubal, that should answer some of the questions you had about my ‘methodology’.

Any thoughts on this?

I got all of that on the first round. Apply the multires at level 4 else you won’t be able to adjust it to fit the level 7 baked image. As far as opening a multires image in another app I doubt that any will support the feature but, who knows, try it and see. Why do you want to open it in another app though? All of this is perfectly reasonable in Blender.

Hi RamboBaby,

I also use Realsoft 3D [ ] - I am doing some experiments with getting sculpted LOOKING meshes from a sculpt app like Blender over to RS. Really to get a lower res mesh over as OBJ and apply the ‘detail’ as bump height bump on the surface of the lower res obj. A sheep in wolfs clothing so to speak.

Yip - if you decrease the multires to 4 from 7 and UV Unwrap, then export out to OBJ. The UV and object translate across perfectly into Realsoft. I get the exact UV as in Blender in RS’es UV Window and the mesh looks exactly like Multires 4. I am trying to avoid bringing across the much heavier level 7 version.

As Blender is a free Sculpt app and RS has alot of Blender users also I wanted to try get a workflow going as RS does not have sculpt tools.

By the way - the above explanation was more for Roubal, as I percieved that Roubal didnt get what I was saying - but sorry to both of ye if ye did.


Well - I think I am moving in the direction of XNormal to fill in the gap. Getting bump height map from this app. [ new ver requires latest Directx - June 07 ]


I looked at XNormal and even downloaded it a couple of weeks ago but haven’t had the guts to learn it. I’m kinda on software overload as it is and I’m just tired of trying to learn new apps when there’s so much that I don’t know about the ones that I play in every day. It looked good except for some of the stuff that I read about seams, which I also get in Blender.

Yes, App overload, I suffer from this too … although I have it narrowed to Realsoft 3D and Blender at the mo. I think - for the moment XNormal is the missing link out of Blender to other apps for this kind of thing, so am giving it a go. Easy enough really, but must find best practise from Blender to it,