Hello
I really start to love zbrush. Tks to pixolator’s fish movie, I was able to create this little model.
(well I don’t control every tools right now, but I need some practice ;))
I would like to paint a bump map on this model, and the only way I find so far is to apply a colorbump shader, so the color channel is used as bump too. But it’s not very handy, I mean I would like to to paint the bump without change the color. Does it make sence 
???
very good question. bump maps are suported through shaders only, and they can’t be painted real-time.
a displacement map usually makes a good bump map also. I would suggest raising up the resolution, making a displacement map using the high-res version, and using it as a bump map on the regular res version…
Actually you can create a bump map for use in other apps, it won’t work in ZBrush though. Somewhere on this site Pixolator posted a Bumpmapper material (I think that’s what it was called) It works in the same way as colour bump but you paint in shades of grey. You should be able to turn it up with a search. If I find it I’ll post a link! - Baz
wow that’s some quick replies thks a lot.
I’ll make some extented research too.
That’s said it’a a pitty, I mean the colorbump shader work pretty well to preview the bump, if only the color channel can be hided to view the bump only.
Game Master 770> Yes you’re right. And for this model I really don’t need a bump too, there is enough polys to create super crisp details. But in the other hand “simple bump” will help to keep the model under 3.000.000 polys.
Btw it would be so great if zbrush will handle normalmaps in realtime too. Let’s imagine you use texture master to create some displacement, but instead of pick the result as a deformation, the result is store in a normal map (tangant) and showed in realtime That would be soo sweet !
The bump mapper mat does exactly what you want, you paint in shades of grey but you only see the bump effect, not the paint.
I’ve had a search myself and I’m afraid I can’t find it, beginning to wonder if I dreamed it LOL! Nah, I’m sure it’s here somewhere. Hopefully someone will remember where it can be found! 
- Baz
I hope, I have more less read every posts with “bump” as keyword, but maybe I miss it … tks for your help and for your time !
The BumpViewerMaterial is included with Zbrush2. Load it from the materials folder.
If you are using Zbrush 1.55b the material can be found here And a nice example by SkyCastle here.
There is some bump mapping info in the Z2 Help script under Modelling 3D Objects 
Textures and Texturing Bump Maps.
hey, thanks TVeyes, I can’t believe I’m painting bumps. can anybody explain how and why this material works? So much of the materials is undocumented.
The difference between a displacement map and a bump map is the way that it is used by your rendering engine. In fact, in ZBrush if you apply a displacement map and don’t activate the Mode switch, then it displays as bump instead.
This means that with ZBrush 2 the best way to paint a bump map is to sculpt a high resolution version of your model and then create a displacement map. You can use it in the bump channel in your rendering engine for extremely high quality results.
Thanks for bailing me out TVeyes!
GM770: Material modifiers add/subtract from the RGB of Pixols and if the modifier is at its max value it can completely replace the visible color. If you switch to Fast or Flat render mode you can see the texture is still there it is only when the material is calculated it can override the pixols RGB (Preview & Best render modes).
The BumpViewerMaterial simply has Reflection set at 100 and the Reflect Curve at max values. The pure white 256x256 texture in the Material Texture slot is used for the Reflection. As the reflection settings are at their max they override the colors of the texture. It is reflecting pure white from all angles. The bumps are still there because the Color Bump modifier is calculated from the RGB value of the pixols not the material shaded RGB values.
You can get the same bump viewer effect by setting Colorize Diffuse, Colorize Specular and Colorize Ambient to 100 and selecting pure white for the Diffuse, Specular and Ambient color modifiers. (Note, you only need to set the Colorize modifiers if their corresponding shading material modifier is >0)
Aurick if you are rendering with displacements I do not think it is a good idea to also use the displacement map as a bump map. They should be kept seperate and unique IMO. The bump map should describe smaller details. I don’t think that was what you meant though Just clarifying.
Thanks a million for your help TVeyes, I can’t wait to be at home to test it !
I wasn’t referring to using the displacement map as a bump map in addition to displacements. My post was to say that if your rendering engine doesn’t support displacement mapping, you can use the map for bump instead. There is literally no difference between a displacement map and a bump map. The only difference is in how that map is used by your rendering engine. So if you need to create a bump map, the same techniques apply as for creating a displacement map.
Now let’s say that your rendering engine does support displacements, but not sub-pixel displacements. In this case, you could create two displacement maps. The first map would be for the difference between the lowest subdivision level and the highest. This would give you the finest details, and would be used in your bump channel. Next, delete a few of the highest levels and create another map. This one would be used for displacements. It will make broad changes to your model’s profile while the first map (the bump map) provides the additional fine detail.
Either way, the bump viewer material has by and large been replaced by the technology in ZBrush 2. It IS still a viable way to work, but the displacement-as-bump-map approach is more efficient. After all, it’s easier to simply sculpt the exact detail that you want than to guess at the amount of greyscale value you need for a particular effect. Of course, if your system won’t support the high number of polygons necessary to create a high quality difference map, then the Bump Viewer material would be the best approach after all.
Thanks for the further explanation Aurick. Very good and succinct 
I still have a fondness for the bump viewer material though 
Cheers BazC and Paq. Paq, if you use an RGB value of 128,128,128 for the base texture you can easily split the final bumpmap in two parts, positive and negative. When you are finished painting the bump map convert it to an Alpha (Texture : Make Alpha) and load the NegativeDisplacement and then PositiveDisplacement alpha adjust curve, while exporting the alpha after each alpha curve adjustment.
Just an idea. All depending on your application you can do some nifty tricks with seperate bump maps.
<BLOCKQUOTE>quote:</font><HR> if you use an RGB value of 128,128,128 for the base texture you can easily split the final bumpmap in two parts, positive and negative. <HR></BLOCKQUOTE>
generally speaking, bump maps automaticly are positive and negative from 128 grey. Also render engines don’t support 2 bump-maps. How would this be useful?
It’s always cool to find little tricks like that.
<BLOCKQUOTE>quote:</font><HR> Also render engines don’t support 2 bump-maps <HR></BLOCKQUOTE>
The end result is always going to be 1 bump effect…unless parallel universes exist 
<BLOCKQUOTE>quote:</font><HR> How would this be useful? <HR></BLOCKQUOTE>
Control and adjustability. You can create variations of your initial bump map, reduce the effect of high areas without affecting the low, animate bump maps. There are many more uses.
Variations of the initial bump map (top left):
Controling shading propertives (No texture map):
You could also use the divided bump map to control where hair/grass is applied and it will fit without any extra work. I used LightWave for the above pictures but most 3D programs can do the same.
very insightfull TVeyes! excelent pix to go along with the idea too. Can you explain better on how you did the last 2. (additive, additive+inverse)
As far as I can tell, the 1st 2 are a standard bump-map, 1 is positive, the other negative. any details on this would be great, since the idea is new to me. (using 2 ends of a bump map)
Ignore the additive/inverse +additive description, I was in a bit of a hurry.
This should explain it more clearly. However, the way your render app blends bitmaps may be different. In LightWave the top one is additive and the bottom subtractive. You could use photoshop to create the same effect but you will loose the control and possibilities 2+ maps give you.
There are more combinations/blend modes that will give the same effect. The above two is just what I settled on.
<BLOCKQUOTE>quote:</font><HR> As far as I can tell, the 1st 2 are a standard bump-map <HR></BLOCKQUOTE>
Yeah, I was in a hurry Just close your eyes and imagine the second picture is subtracting the positive without affecting the negative
that helps to explain it much better. Next step would be to try it in either Max or trueSpace. (I haven’t gotten the hang of LW yet)
<BLOCKQUOTE>quote:</font><HR> Just close your eyes and imagine the second picture is subtracting the positive without affecting the negative <HR></BLOCKQUOTE> :eek: Ahh, got to go now, my eyes are bleeding. What did you do to me? 
can someone please save a zscript on how to make such or siml;ar bump maps, please i beg you!