The "Real Time rendering"  is different from traditional Rendering Techniques :the settings are studied and optimized so that the rendering is just "instantaneous".

The rendering process, especially for big scenes and complex effects, reminds a bit of film photography:

You build the scene, you place the lights, the materials, you set the shot you want, you launch the rendering process, and then you wait to see the results.

Seconds, minutes, hours, days... depends on the scenic complexity, the selected settings, the resolution, the light refractions and the plotting of the shadows.

It is a work of intuition, in which you cannot have an immediate visual response. 

My (and other) personal interest and research topic, is to creatively use the functions of realistic representation of these tools, and, playing around on their limits and errors, to create something that steps away from realism in a pictorial or abstract way.

Passing between several excellent evolutionary steps, and coarse and plasticious attempts we reach, first the perfection of special effects in holliwood films, and lately the integral creation of the entire film, including the characters, in some modern films, such as "The Legend of Beowulf "of 2007, or several scenes of" Star Wars ", in which what perhaps shows that we are dealing with totally digital creations is only the careful observation of the movements and expression of the characters, or the excessive perfection of some scenic elements.

Wireframe rendering: "wire" representation

Surely the "lightest" and most abstract three-dimensional representation method: polygons are traced on the screen by simply following the contours and the construction lines.

It constitutes the constructive basis of digital polygonal units, in practice a skeleton that over the years has been "filled", with the evolution of the rendering technique, from the reproduction of physical phenomena such as:

Introduction

One of the most versatile tools to support current artistic creation, and which I better master is in my opinion what is called "3d modeling", "3d animation", "3d design" etc.

Like many other artistic instruments, it was born (in the mid-70s) with different intentions, and more precisely as a support for architectural design, vehicles, and objects of common use intended for industrial production:

CAD = Computer-aided design.

Basically, this tool allowed:

Computer calculated motion , Computer Generate Art, Auto Generated art etc

A vast topic, in which I can not dive too much in this place.

The movements and images are automatically calculated by the computer on the basis of mathematical formulas, which in turn can be extrapolated in real time from music, captured movements or anything else.

Or the images and movements can be transformed into music.

A "concrete" application, for example, can be the creation of fluids in a 3D animation, in which liquid bodies will deform according to the laws of physics.

(Capture of Movements) and Motion Sensors:
A technique that allows you to capture the movements of a real character, and transfer them to an "imaginary" digital character.
It can be implemented by applying electrodes on the actor, which will act as key points for the skeleton of the virtual character, or, through software support, simply through one or more cameras, better if "3d", like that of the Xbox console, which intelligently will break down the subject into polygonal units and will be able to trace the most important movements.

Morphing (Mutation):

Technique that consists in gradually transforming one image into another.
Widely used (and easy to implement) in stop motion, the plasticine is gradually deformed, and enriched with new elements until it reaches the desired result.

An example of this are both motion pictures in stop motion, and many special effects, including those of films such as "The Evil Within", which witnessed the metamorphosis of human becoming  demons.

Rotoscoping An animation technique that consists in tracing the frames of a shotted film, with real actors and other elements (humans, animals, or physical events) to study realistic movements and apply them to an animated subject.

Used in a very productive way in a large number of animations, including the Disney ones, or in videoclips like Take on Me" from the A-ha