Abstract: A method 100 of displaying a three dimensional volume of an image on a two dimensional display. For each pixel in the two dimensional display, the method comprises sequentially stepping 102 through a plurality of points along a line of sight from the pixel into the three dimensional volume and determining 104 a first point along the line of sight at which the three dimensional volume has a value that satisfies a first criteria indicating that the first point comprises a surface of interest in the three dimensional image. From the first point, the method then comprises determining 106 a second point that lies normal to the surface of interest at the first point, and determining 108 a value for the pixel based on a first value associated with the second point.

Abstract: Instead of tracing using first rays of the ray tracing method, an object is divided into a plurality of triangles, each triangle is projected onto a screen, and data on a three-dimensional coordinate space are converted to data on a screen coordinate system. Pixel data inside a triangle are generated by interpolation based on data of the three vertices of the triangle on the screen coordinate system. Pixel data are corrected by performing a tracing operation using second rays on the pixel data generated by the interpolation.