In which of the following shading models of polygons, the interpolation of…

Gouraud shading is the correct answer because it specifically interpolates intensity values across polygon edges and along scan lines. First, vertex colors are calculated using lighting equations at each corner of the polygon. Then, these intensity values are linearly interpolated along the edges and subsequently across each scan line to produce smooth shading. This method creates a continuous gradient effect within the polygon.\nPhong shading differs by interpolating surface normals rather than intensity values, performing lighting calculations per pixel for more accurate specular highlights. Constant and flat shading do not perform any interpolation; they assign a single uniform color to the entire polygon. Since the question explicitly asks about interpolating intensity values along scan lines, Gouraud shading is the only model that matches this description.