OBJECT RENDERING
COMPUTER GRAPHICS
UNIT VI
-BY MS. ARTI GAVAS
INTRODUCTION
• The objective of this chapter is
▫ To understand light modeling techniques and illumination
models.
▫ To understand different types of shading models.
▫ To understand concepts Ray Tracing and Radiosity.
An illumination model is used to calculate the intensity of
light that we are going to see at a given point on the surface of
an object. Illumination models are also some time called as
lighting or shading models.
LIGHT MODELING TECHNIQUES
• The object may be illuminated by light which can
come from all direction.
• A surface that is not exposed directly to a light
source will be still visible if nearby objects are
illuminated.
• In basic illumination model we can set a general
level of brightness of a scene. The method by
which we create such effect usually follows the
laws of reflections.
LIGHT MODELING TECHNIQUES
• Two types:
▫ Diffused illumination
▫ Specular illumination
light incident on each object is constant for all the surfaces and for
all the direction. When the illumination is uniform from all
directions it is called ‘diffused illumination’. Usually diffused
illumination is a back ground light which is reflected from walls
scenes and curve ceiling, floor.
When we illuminate a shiny surface such as polish metal we observe
highlight or bright spot on the shining surface. This phenomenon of
reflection of light in concentrated area around the reflection angle is
called specular reflection. Due to specular reflection the surface
appears to be not in its original color but white, the color of the
incident light.
ILLUMINATION MODEL
• An illumination or lighting model is a model or
technique for determining the colour of a surface
of an object at a given point.
• A simple illumination model can be based on
three components:
▫ ambient reflection,
▫ diffuse reflection and
▫ specular reflection
ILLUMINATION MODEL
SHADING
• A shading model is used in computer graphics to
simulate the effects of light shining on a surface. The
intensity that we see on a surface is dependent upon
two things one the type of light sources and second
the surface characteristics:
• Ex. Shining, matte, dull, and opaque or transparent.
• Types:
▫ FLAT SHADING
▫ POLYGON MESH SHADING
▫ GAURAND SHADING MODEL
▫ PHONG SHADING
FLAT SHADING
FLAT SHADING
POLYGON MESH SHADING
POLYGON MESH SHADING
GAURAND SHADING MODEL
GAURAND SHADING MODEL
PHONG SHADING
PHONG
SHADING
TRANSPARENCY EFFECT
TRANSPARENCY
EFFECT
SHADOWS
TEXTURE AND OBJECT REPRESENTATION
TEXTURE AND OBJECT REPRESENTATION

Object rendering

  • 1.
  • 2.
    INTRODUCTION • The objectiveof this chapter is ▫ To understand light modeling techniques and illumination models. ▫ To understand different types of shading models. ▫ To understand concepts Ray Tracing and Radiosity. An illumination model is used to calculate the intensity of light that we are going to see at a given point on the surface of an object. Illumination models are also some time called as lighting or shading models.
  • 3.
    LIGHT MODELING TECHNIQUES •The object may be illuminated by light which can come from all direction. • A surface that is not exposed directly to a light source will be still visible if nearby objects are illuminated. • In basic illumination model we can set a general level of brightness of a scene. The method by which we create such effect usually follows the laws of reflections.
  • 4.
    LIGHT MODELING TECHNIQUES •Two types: ▫ Diffused illumination ▫ Specular illumination light incident on each object is constant for all the surfaces and for all the direction. When the illumination is uniform from all directions it is called ‘diffused illumination’. Usually diffused illumination is a back ground light which is reflected from walls scenes and curve ceiling, floor. When we illuminate a shiny surface such as polish metal we observe highlight or bright spot on the shining surface. This phenomenon of reflection of light in concentrated area around the reflection angle is called specular reflection. Due to specular reflection the surface appears to be not in its original color but white, the color of the incident light.
  • 5.
    ILLUMINATION MODEL • Anillumination or lighting model is a model or technique for determining the colour of a surface of an object at a given point. • A simple illumination model can be based on three components: ▫ ambient reflection, ▫ diffuse reflection and ▫ specular reflection
  • 6.
  • 7.
    SHADING • A shadingmodel is used in computer graphics to simulate the effects of light shining on a surface. The intensity that we see on a surface is dependent upon two things one the type of light sources and second the surface characteristics: • Ex. Shining, matte, dull, and opaque or transparent. • Types: ▫ FLAT SHADING ▫ POLYGON MESH SHADING ▫ GAURAND SHADING MODEL ▫ PHONG SHADING
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    TEXTURE AND OBJECTREPRESENTATION
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    TEXTURE AND OBJECTREPRESENTATION