Many real world objects are inherently smooth and involve curves to represent them some natural objects are neither perfectly flat nor smoothly curved but often have rough jagged contours. These objects have different characteristics and different materials. So there is no one method to describe such objects.

Polygon and Quadric surfaces provide precise description for simple object such as polyhedrons and ellipsoids. The spline surfaces and construction techniques are useful for designing aircraft wings, gears and other engineering structures with curved surfaces. The procedural methods such as fractal constructions and particle system allow us represent mountains, clouds, clumps of grass etc. The physically based modeling methods are useful for describing nonrigid behavior of objects such as cloth. The Octree encoding is used to represent internal features of object such as obtained from CT scans.

Comparison of 3D objects representation methods:-