Normal map: the effect of the associated scale parameter

lamoid_5f20d3e469

Under the surface tab in Daz studio there is an entry for a normal map. For a given surface one can assign a map -- a 3-band image that conforms to the UV map for the surface. Beside the square where a map can be assigned, there is a parameter slider that defaults to lie between 0 and 1. 

Q: in Daz Studio does that slider have any effect? If so, what is it?

In Studio, if a surface has an associated normal map, that map is a 3-band image that (I think) represents the direction of a surface normal at each point of the surface. Please correct me if I am wrong about that. In general 3D geometry, a surface normal is a direction, a unit vector defined by direction cosines with respect to some coordinate system (e.g. world, object, camera). There is no magnitude associated with a surface normal; if (x,y,z) is [the direction of] a normal vector at location (u,v) and n > 0 is a real number then vector (nx,ny,nz) has exactly the same direction as (x,y,z). n, if greater than zero, has no effect. In Studio, n would be defined by the position of the parameter slider. Based on that I would conclude that the position of the parameter slider has no effect whatsoever on the result. But, Daz might use that slider for something other than scaling the normal. Do you know if it does and if so what that is?

I have no doubt that this question has been asked and answered before in these forums. I spent quite a bit of time searching for the answer but could not find it. Since DAZ, in general, does not provide detailed documentation for its products but leaves it up to us to figure it out then share help on the forum, and since the search engine associated with this forum is very limited in capability, searching for the answer to such a narrowly focussed question is like finding the proverbial needle in a haystack. So please forgive me if the answer already exists. Feel free to point me to it if know exactly where it is.

DrunkMonkeyProductions

the short answer is yes it will have an effect.

what the slider does is change the intensity of the map.

At 0 the details from the normal won't be present. At 1 the normal map will add the details as intended, generally.

Anything in between will make them less, or if you turn off limits make them more intense.

 

In essence a normal map is just a variation of the bump and displacement map and serves a similiar function.

That is to add details without manipulating the mesh.

 

lamoid_5f20d3e469

Thank you DMP!  You are saying that each 3-color pixel in the map [(R,G,B) at location (u,v)] represents not only the direction of the surface normal but also the displacement of the surface in that direction or, equivalently, the magnitude of the displacement in each of the three principal drections. The slider then scales that displacement between a maximum and minimum amount. Correct?

That makes sense. But I have two followup questions: (1) Does the scalar value given by the slider simply multiply the values in the map? (2) What is the coordinate frame of the principal directions specified by the R, G, and B values in the map? Is it with respect object coordinates, the UV surface coordinates with the normal at each point defined by the object geometry, or some other coordinate frame?

Thanks again