Rendering Method

Q: Explain rendering methods in detail. Write its advantage and disadvantage.

Advantage of illumination method:-

1. Fast
2. Acceptable results
3. Hardware support

Disadvantage of illumination method:-

1. Point light source
2. No interaction between objects
3. Adhoc , not based on model of light propagation.

Different rendering method:-

Constant-intensity shading:-

1. In this method, a single intensity is calculated for each polygon and all points in the surface of polygon are displayed with the same intensity value.
2. It is fast and simplest rendering method.
3. Light source illuminating the object and the viewing position is sufficiently far from the surface of polygon.

Gouraud shading:-

1. It represent a polygon surface by linearly interpolating intensity across the polygon surface.
2. Intensity values for each polygon are matched with adjacent polygon along common edge.
3. It eliminates the intensity discontinuity that can occur in constant-intensity shading.

Phong-shading:-

1. Phong shading is method which interpolates normal vector and then apply the illumination model to each surface point.
2. This method interpolates the surface normal vector, instead of the intensity.

FasePhong shading:-

1. Fast phong shading approximates the intensity calculations using a Taylor-series expansion and triangular surface patches.
2. Surface rendering with Phong shading can be speeding up by using approximations in the illumination model calculation of normal vectors.

Advantage of rendering method:-

1. It removes the intensity discontinuity.
2. It can be combined with hidden surface algorithm to fill in the visible polygon along with each scanline.
3. It gives more accurate result.

Disadvantage of rendering method:-

1. It has a problem with specular reflections.
2. It introduce anomalies known as Mach bands.
3. It acquires more calculations and increases the cost of shading steeply.