What is a Normal?
What is a normal? Am I normal? No one seems to know… the answer to the second question. There is although very specific reasons for taking a deeper look at Surface Normals in 3D applications which may help you solve problems later.
There are usually 2 sets of data for normals, N1 and N2, on a surface these calculate “inside” and “outside”. In modern 3D applications N1 is often represented by a point with a line extruding. N2 is the inverse direction.
In all 3D applications, a Surface Normal is a calculation of a vector that is perpendicular to the surface. It is used to render the surfaces direction towards a light source effectively giving a direction for the rays bouncing off and creating the illusion of 3D.
Often times while modeling, Normals become mixed up, which usually goes unnoticed until you begin to light or texture the scene. Forums are scattered with questions about errors they cant seem to figure out, usually followed by a screen shot of the issue. The response is always to re-align your normals, which is a very simple one button, no variable tool.
While this process is very stream lined and generally can pass under your radar, knowing what is going on with your normals can help you from having to ask the embarrassing novice modeling question of, “What the hell is happening here?!”, and can also allow you see new possibilities for using normals to achieve unique styles and effects.
Take a peek at this informative and slightly mesmerizing animation of normals.
Normals also help you understand Normal Mapping, which I will dive into next article. Thanks guys!
Hey guys! I like to play with 3 dimensions of space and 1 dimension of time, but unlike Einstein, I only make motion art. So I spend most of my time expressing myself in some abstract, visual way, and I have really latched onto Motion Graphics. I am a newbie here in the field, but I have a passion for the work. Feel free to if you are also a newbie or someone just looking into this awesome form of art, I always enjoy helping people out.
Good explanation, but getting a little heady. I mean, this is very technical stuff, but you never really answered your first question: “What is a normal?”
Fair enough, it is very technical but definitely not out of reach. I am hoping to take certain technical aspects that we use every day in 3D applications and give a little background on them. I feel that too often do we watch tutorials and copy the concepts, but never realize why we use the concept to begin with. Definitely call me out if it doesn’t make sense though!
I did answered my question of “What is a normal?” in the paragraph
It describes the “outside” and “inside” of a flat polygon plane (made up of 3 or more vertices). This becomes important in normal mapping (which I will get into next time), phongs, and modeling (inorder to fix errors). With out a surface normal a computer wouldn’t know which side of a face is in and which is out. It also wouldn’t know how to bounce rays of light off in the correct manner.
Did that help any?
Sorry. I guess I must have overlooked the Surface Normal paragraph while looking for the definition of what a Normal is.
Thank you for the clarification. Still a very technical topic. Perhaps some more illustrations to assist in the explanation? Can’t wait for the next article(s) to see these concepts in action!