Construction of 3D Models
Modelling Techniques
Polygonal
In polygonal modeling, an artist creates a digital representation of a 3D object with a geometric mesh composed of faces, edges, and vertices. Faces are usually quadrilateral or triangular, and make up the surface of the 3D model. http://3d.about.com/od/Creating-3D-The-CG-Pipeline/tp/Polygonal-3d-Modeling-Common-Box-And-Edge-Modeling-Workflows.htm
Models often start from a simple primitive, such as sphere or a cube, because it makes the first step easier. Alternative is to manually start of with creating points and joining them into edges. Polygons are being changed, added or subtracted from a mesh. The more 'polys' the model contains, the more detailed it looks, and the more memory it takes. Alternatively subpatch can be used.
If the model goes into a game, no matter how it was done, later on it's transformed into a polygonal mesh made out of triangles.
Primitive
Primitive modelling is made by combining predefined 3D shapes called primitives. Most common, basic ones are
- cubes,
- spheres,
- cones,
- piramids,
- cylinders
These primitives can be used as a foundation for a model, or may not be altered, thus left in their original form. the second way looks like making a model out of LEGO blocks.
Box
Box modelling is a polygonal modelling where the model is created out of the box primitive. The box it then modified in many ways, the first one is subdividing walls of the mesh, then they are moved, resized, more polygons are added etc.
Extrusion
With extrusion modelling, the model is prepared on a flat surface, by either making polygons manually inside the modelling software or in programme such as Adobe Illustrator and then being exported into the software. All the polygons are then extruded for a specified width and placed all together.
Sketch
Sketch or sculpt modelling, is the easiest way to model in 3D, as it looks like working with digital clay. The shapes are 'sketched' in 2D way, and then transformed into 3D objects.
3D Scanner
3D scanning is a quick way to generate models out of real life objects and humans. It achieves that by taking series of photos/scans and the distance is then being calculated and send into a software with a ready mesh.