COMPUTING ILLUMINATION OF AN ELONGATED SHAPE HAVING A NONCIRCULAR CROSS SECTION

The system obtains an indication of a shape of a cross-section of an elongated shape, and an orientation of the shape. Based on the shape of the cross-section of the elongated shape and the orientation of the shape, the system creates a nonuniform distribution of random numbers mapping uniformly distributed input values to multiple points on the surface of the elongated shape. The system provides an input value randomly selected from a uniform distribution of random numbers to the nonuniform distribution of random numbers to obtain a point among the multiple sample points on the surface of the elongated shape. The system applies a function to the input value to obtain an indication of a normal associated with the sample point among the multiple sample points. Finally, the system computes an illumination of the elongated shape using the normal.