Character Modelling and Edge Loops

Why is it so important to construct sound models? Edge loops are particularly important under a humanoid character’s arms and on their face- why is this?

The most essential lesson to learn in modelling a character is too make sure not only that your model and geometry are neat but that there are less triangles and five sided polygons as these tend to cause problems when manipulating the mesh for animation purposes. Triangles (although all polygons are ultimately triangles) are the worst for deformation of the character, they act like spear heads and points jut out when deforming and therefore the operatic ability of the triangle is limited (Ratner, 40). The best solution is to form quads instead of other polygon types as they allow for maximum control and deformation. Low geometry is also good for a character as it allows for high definition smoothing whereas a high polygon count will allow for little smoothing capacity and will slow down the animation and render process (Unknown, 1)

Character modelling is quite a complex task consisting of a variety of formulas and methods that will produce the required results. There are two types of modelling techniques, namely polygon modelling and patch modelling. Polygon modelling refers to a subdivision surface type of modelling whereby one can choose from an existing shape or polygon and begin modelling there. Patch modelling is a more detailed and intricate process that deals with NURBS and spline-based surfaces. It is seen as building from scratch and is used for organic modelling which can allow for amazing results in facial modelling (Murdoch; Allen 37). Now with these techniques come sub-techniques/ methods that can be used with for modelling but here we shall pull focus to edge loops.

Edge loops are defined as a series of polygons connected by edges in a loop, end-to-end format. Therefore where the loop begins is where it ends and so the edge loop is a recurring flow of polygons (Murdoch; Allen, 44).  Edge loops act and are defined similarly to the muscles of the human body. When creating a character the edge loops must run in the same fashion as the muscles of the face and body as this will create a natural and real deformation for animation.

 “Edge loops will make deformation, motion and even texturing quite a bit easier” (Osipa, 80)

Edge loops are essential for expressions as there is a natural flow of motion in the loop, giving a natural effect of movement and deformation.  Murdoch and Allen describe a couple of advantages of edge loops- edge loops allow for easy movement, and changing the position of an edge loop is quick and easy. They segregate different major features of the body and allow for even greater definition such as wrinkles. Heavily deformed/ animated areas need edge loops to stop the mesh from distorting and pulling unnaturally. The polygon count is quite low in edge looped characters as the need for definition is lower as the edge loops provide maximum definition. (Murdoch; Allen, 45-46)

Here are some examples of edge loops and the key areas in which they should be created:

Facial topology:

 

The eyes and the mouth are the main areas and then the nose cheeks and forehead should be connected to the adjacent areas as seems natural. (Cryrid, 1)

Limb and connection topology:

The shoulder’s movement must be diverse and fluid, and must be able to handle any stress the arm deals it. It must therefore allow strain in the chest area, the shoulder area and arm area, which in turn becomes edge loops connecting these areas. This is one method; another one is to take many edge loops to the shoulder allowing for much slack to deform and animation. ( Chadwick, 1)

The knee and elbow areas of the character must have edge loops like that of the mouth dedicated to handling the strain of a bend. Weight painting may become redundant if the loops in the areas are limited. (Chadwick, 1)

Edge loops are a clean and safe way to model, texture, rig and animate. They have many advantages and whether one uses the patch or the polygon method, the edge loops should be there making 3D character animation an easy and quick process. By using edge loops, one not only prevents problems, but creates a greater outcome.

Works Cited:

•  Chadwick; Cryrid. Polycount Wiki. 2010-09-17.Web. 06 May 2011.

• Murdoch, K. L. and E. M. Allen Edgeloop Character Modeling: For 3D Professionals Only. Indiana, Wiley Publishing, Inc. 2006. Print. 
•        Osipa, J. Stop Staring: Facial Modeling and Animation Done Right. 3^rd Ed. Indiana, Wiley Publishing, Inc. 2010.
•        Ratner, P. Mastering 3D Animation. 2^nd Ed. New York. Allworth press. 2006. Print. 
•     Unknown. Modeling With Edge Loops. 2008-04-02. Web. 01 May 2011.