Why is Gouraud shading also referred to as interpolation shading ? Also discuss its advantages and disadvantages.

Gouraud shading :-

• It represents a polygon surface by linearly interpolating intensity across the polygon surface.

• Intensity values for each polygon are matched with adjacent polygon along common edges.

• It eliminates the intensity discontinuity that can occur in constant?intensity shading.

• Gouraud shading is a trick whereby values for lighting, fog, and so forth are computed at the vertex level. These values are then linearly interpolated across the face of the polygon.

• Due to the use of linear interpolation Gouraud shading is also referred to as interpolation shading.

Advantages :-

• Gouraud shading can be combined with a hidden surface algorithm to fill in the visible polygons along each scan line.

• It removes the intensity discontinuities exists in constant shading model.

Disadvantages :-

• Highlights on the surface are sometimes displayed with anomalous shapes.

• The mach band effect can be reduced by breaking the surface into a greater number of smaller polygons.

• Sharp drop of intensity values on the polygon surface cannot be displayed.