Short-Question

Flat shading involved a single illumination calculation per triangle. Gouraud shading requires three illumination calculations per triangle, plus the interpolation of a single attribute, the illumination, across the triangle. The next step in quality requires us to calculate illumination at every pixel of the triangle.

### Why is Phong shading better than Gouraud?

Phong shading improves upon Gouraud shading and provides a better approximation of the shading of a smooth surface. Phong shading assumes a smoothly varying surface normal vector.

What do you understand by Gouraud shading?

Gouraud shading, named after Henri Gouraud, is an interpolation method used in computer graphics to produce continuous shading of surfaces represented by polygon meshes.

What is the main problem of Gouraud shading?

One problem with Gouraud shading is that it does not really simulate a curved surface. On a real curved surface, the normal changes direction within a surface patch. The intensities that result may not correspond to linear interpolates of the vertex intensities.

## What is Gouraud and Phong shading?

Gouraud shading (AKA Smooth Shading) is a per-vertex color computation. In contrast, Phong shading is a per-fragment color computation. The vertex shader provides the normal and position data as out variables to the fragment shader. The fragment shader then interpolates these variables and computes the color.

This Intensity-Interpolation scheme, developed by Gouraud and usually referred to as Gouraud Shading, renders a polygon surface by linear interpolating intensity value across the surface. Linear interpolate the vertex intensities over the surface of the polygon. …

Phong shading is today evidently used in most modern 3D graphics engines, including Crytek’s CryEngine series, Valve’s Source Engine, Epic’s Unreal Engine 3 & 4, Square Enix’s Luminous Studio, and Kojima Productions’ Fox Engine, among others.

The idea of interpolative shading is to avoid computing the full lighting equation at each pixel by interpolating quantites at the vertices of the faces.

The advantage of Gouraud shading is that it is computationally the less expensive of the two model, only requring the evaluation of the intensity equation at the polygon vertices, and then bilinear interpolation of these values for each pixels.

What are the disadvantages of Gouraud surface rendering?

Its main disadvantage is the amount of memory required for the Z-buffer. During the implementation of Z-buffer hidden surface removal in Phong Shading and Gouraud Shading, the rasterizing of polygon is to be implemented to fill the polygons with the pixel value.

How is the normal used in Gouraud shading?

The normal N used in this equation is the vertex normal which is calculated as the average of the normals of the polygons that share the vertex. This is an important feature of the Gouraud Shading and the vertex normal is an approximation to the true normal of the surface at that point.

## Who is the creator of Gouraud shading algorithm?

Gouraud shading was developed by Henri Gouraud. Gouraud shading was first published in 1971. In Gouraud shading, each polygon has one normal vector per vertex, but instead of interpolating the vectors, the color of each vertex is computed and then interpolated across the surface of the polygon.

### How is specular reflection used in Phong shading?

For a perfect glossy surface, all the light is reflected along the mirror direction. The area over which specular reflection is seen is commonly referred to as a highlightand this is an important aspect of Phong Shading: the color of the specularly reflected light is different from that of the diffuse reflected light.

When was the Phong shading algorithm first published?

Phong Shading was developed by Phong Bui Tuong. It was first published in 1971. It was first published in 1973. Each polygon has one normal vector per vertex, but instead of interpolating the vectors, the color of each vertex is computed and then interpolated across the surface of the polygon.