1. A method for rendering a 3D model of a 3D object as an image including image samples, wherein the 3D model is a distance field, and the distance field includes surface cells representing portions of a surface of the 3D object, comprising the steps of: determining, in an object-order phase for each surface cell, a set of image samples in the image; processing each surface cell, independent of other surface cells, wherein the processing of each surface cell further comprises: casting a ray, in an image order phase from each image sample in the set of image samples, through the surface cell to determine a contribution of the surface cell to the image sample, wherein the casting determines, using the distance field, if an entry point where the ray enters the surface cell and an exit point where the ray exits the surface cell are both inside the surface, and if true, the contribution is determined from the entry point; and rendering the image, wherein steps of the method are performed by a processor.