bump and normal

[super gnu]

just been playing with nvidia normal map generator thingy in photoshop.

since bump maps converted to normal maps seem to work much better than bump maps for doing bump mapping, shouldnt vray do this conversion transparently internally? that way all bump maps would look as nice as normal maps?

[Svetlozar Draganov]

Yes this could be done automatically via VRayBump2Normal texture, please check the link bellow:
http://forums.chaosgroup.com/showthr...ht=bump2normal

[super gnu]

Ok thanks for the tip, although I think what I was meaning was, when you put a bump map in the bump slot, why doesn't it use it in the same way by default? Without having to plug in two extra nodes? It works much better than the way vray normally processes a bump map.

[vlado]

that way all bump maps would look as nice as normal maps?

Normal maps are generally easier on the renderer, as a single texture lookup is enough to find the bumped normal. With bump maps, the renderer needs to evaluate the texture at three different points in order to derive the surface normal. So from that point of view, normal maps are slightly faster to render. But also, in the name of speed, this derivation of the normal "on the fly" for bump maps is not as accurate or precise as it could be when the normal map is pre-generated.

On the other hand, bump maps are easier to manipulate in a shading network, whereas normal maps are somewhat harder...

Best regards,
Vlado

[Alan Iglesias]

Normal maps are generally easier on the renderer...

Vlado, thanks for the nice explanation regarding why Bump Mapping still needs to be retained as an option.

Now, in the name of efficiency, how about a completely new mapping type in the Vray material called Normal2Bump that automates the process for those that want to go straight there? Wouldn't it be fairly easy to implement?

-Alan

[Ihno]

Never seen a normal to bump converter.
I think you can´t simply conclude a Bump Map from a Normal map.

As far as i know a Bump Map is working basically as a Hight Map, that means white areas look like they are pushed out and black areas look like they are pushed in.

The information of a Normal Map on the other hand stores some kind of a Normal-angle offset per Pixel.
With a Normal Map you tell the renderer to shade the pixel like it would do it if the poligon has a different angle in relation to the camera as it has.
Because you can do it per pixel, one polygon can have as mutch different normal angles as pixels mapped to it. So you can make the Poligon look like it has mutch more geometry as it has.

I am not shure about this but this is how i explane it to my self.
It explanes why there is no normal to bump converter out there.

Keeping that in mind you´ll also see that a converted Bump Map will never be as proper as a Normal Map witch is generated by comparing a Lowpoly Mesh with a Highpoly Mesh witch was the idea behind it.

Anyway, i converted Normal Maps for use as Displacement Map a few times. I think you can use it as a Bump map to.
But its a dirty workaround and it is anything but proper.
I used the Normal to Cavity conversion tool of xNormal.
Witch does some kind of fake Ambient oclusion based on the angles the normal map stores. The result can look like a bump map and may look good if its used as one. But as i sad, this is far away from beeing proper.

Edit: I think I miss understood you, you want that vray automatically recognizes which kind of map is plugged in and automatically convert Bump Maps to Normal Maps?