I've seen the term Normal being used in many places, but I'm not quite sure what it is or what it's used for; what exactly are they?
$\begingroup$
$\endgroup$
2
asked Dec 20, 2014 at 18:36
-
$\begingroup$ read: en.wikipedia.org/wiki/Normal_%28geometry%29 and en.wikibooks.org/wiki/Blender_3D:_Noob_to_Pro/… $\endgroup$– user1853Commented Dec 20, 2014 at 18:46
-
$\begingroup$ Already did. That's mostly were the answer originated from. $\endgroup$– someonewithpcCommented Dec 20, 2014 at 18:50
Add a comment
|
2 Answers
$\begingroup$
$\endgroup$
3
Normals are vectors that are Orthogonal to the Tangent plane of a curved surface; Or simply orthogonal to a face.
The Normals are usually used to determine a surface's orientation toward a light source for shading. Most common examples:
Flat, Goraud, Phong shading
Fresnel, Refraction, Reflection effects
- Bump, Normal, Displacement mapping
Normals are generally normalized to length 1 (in arbitrary units), otherwise calculation errors, and thus artifacts, may arise. Since they only point one way they are also used for back visibility culling (when double-sided is off).
That's why it is important for the normals to be consistent and coherent (i.e. point in the correct way - outwards of a model).
Jaroslav Jerryno Novotny
51.4k7 gold badges131 silver badges218 bronze badges
answered Dec 20, 2014 at 18:36
-
1$\begingroup$ Normals are also used for bump and (duh) normal mapping and smooth shading. $\endgroup$– PGmathCommented Dec 20, 2014 at 18:42
-
$\begingroup$ @PGmath well, yeah... Those were just some examples. $\endgroup$ Commented Dec 20, 2014 at 18:44
-
1$\begingroup$ @NoviceInDisguise Yea, it felt kind of dumb saying that normal maps mess with normals. But then again, when I first saw a normal map I thought “that doesn't look very normal to me!” $\endgroup$– PGmathCommented Dec 20, 2014 at 20:35
$\begingroup$
$\endgroup$
1
Besides the mathematical explanations, I think a picture will help to understand what is meant by normals and perpendicular. The faces having a normal (blue lines) pointing to a light source are rendered brighter than the faces pointing into other directions.
You can toggle the display of normals in the Properties Panel (right panel N):
-
1$\begingroup$ +1 if you also add screenshot showing how you turn on the normal lines display. $\endgroup$– NeilCommented Dec 22, 2014 at 8:38