Gouraudsävytyksiä

Gouraudsävytyksiä, also known as Gouraud shading, is a method of interpolation of a scalar value (a color) on the surface of a polygon in computer graphics. It was developed by Henri Gouraud in 1971. Instead of calculating the lighting for each individual pixel, Gouraud shading calculates the lighting at the vertices of the polygon. These vertex colors are then linearly interpolated across the surface of the polygon.

The process typically involves determining the normal vector at each vertex of the polygon. Then, the lighting equation is applied at each vertex to calculate the final color. Finally, these vertex colors are interpolated across the face of the polygon. This interpolation is usually done using barycentric coordinates for triangles or by interpolating along scanlines for general polygons.

Gouraud shading is computationally less expensive than per-pixel lighting methods like Phong shading. However, it can suffer from artifacts, particularly with sharp specular highlights, which may appear smeared or disappear entirely. It also does not accurately represent lighting on curved surfaces, as the lighting is only considered at the discrete vertices. Despite its limitations, Gouraud shading was a significant advancement in rendering smooth surfaces and was widely used in early 3D graphics.