Calculation time: about 15 seconds
Video card: GeForce 2 MX/MX400 CPU: 2.4Ghz
desktop colordepth: 32bpp (!!! not 16)

screenshots in PNG format without scale (1:1):






[pascal]Idea:
1) Polygon[i] -> Lightmap[i]
2) Lightmap[i] -> LigtmapPixel[u,v]
3) Lightmap[i].Pixel[u,v] -> lightmap pixel world coordinates(x,y,z)
4) gluLookAt -> eye position, view direction
eye position:= lightmap pixel world coordinates
view direction:= Polygon[i].normal
6) render scene
7) glReadPixels to RadiosityPointer[a,b]
array RadiosityPointer[a,b] -> Color
9) Lightmap[i].Pixel[u,v]:=Lightmap[i].Pixel[u,v]+Color
10) goto 1[/pascal]

p.s. opengl backbuffer may corrupt during the process (do not move window, do not press alt+tab, use 32bpp mode)