Illumination models

CG

1. ILLUMINATION MODELS

2. ILLUMINATION It is used to calculate the intensity of the object that is reflected from a given point on a surface.

3. AMBIENT LIGHT Ambient light  means the light that is already present in a scene, before any additional lighting is added.

4. POINT LIGHT SOURCE Light which is emitted from single point over a larger area is called as Point Light Source. (Ex) Sun

5. DISTRIBUTED LIGHT SOURCE Light Source which emits light in all the directions is called as Distributed Light source. (Ex) Lamp

6. BEER LAMBERT’S LAW It states that intensity of colour observed from any reflecting surface is directly proportional to cosine of the angle between the direction of incident light and the normal surface .

7. CHROMATICITY DIAGRAM It is useful to identify the complementary colours . It allows to identify the dominant wavelength and purity of the colour . It allows to define the colour Gamuts or colour ranges.

8. CHROMATICITY DIAGRAM

9. FLAT SHADING Here, a color is calculated for one point on each polygon based on the polygon. The color everywhere else is then interpolated by coloring all points on a polygon with the uniform color

10. GOURAUD SHADING Here the Intensity values are calculated of each polygon are matched with the values of adjacent polygon along with edges to draw the color.

11. WARN MODEL

12. WARN MODEL

13. WARN MODEL In the above diagram the light is white, the ambient and diffuse colors are both blue, and the specular color is white, reflecting a small part of the light hitting the surface, but only in very narrow highlights .

14. WARN MODEL The intensity of the diffuse component varies with the direction of the surface, and the ambient component is uniform (independent of direction).

15. PHONG ILLUMINATION MODEL

16. PHONG ILLUMINATION MODEL The values of Specular Reflection lies between 1 to 100 depend upon the surface material. The larger the value ( Specular Reflection ) it is a shiny material. The smaller the value (Specular Reflection ) it is a rough surface.