For completeness, there is an alternative to the cubic
map approach described above. This involves a vertex
shader [14] that transforms each vertex such that when
the result is viewed with an orthographic camera it
appears as a fisheye projection. The resulting fisheye
image is warped by applying it to the same mesh as
discussed above. This is potentially very fast both
because it is a single pass algorithm and because the
vertex shader is implemented on the graphics card