I did some optimizations to the model representation to avoid wasting space, and managed to squeeze the memory requirements for the Lucy model down to 535 MB. I then increased the number of instances to 36 million, reaching an impressive amount of a quadrillion (1e15) polygons. The result (with global illumination):
In this render I've also perturbed the sun ray randomly to give smoother shadows, and added a decal texture to the terrain for more detail (thanks to Mirchiss for complaining about the boring ground). I also added PNG export to the raytracer (earlier I just used KSnapshot), and made a movie zooming in on a single statue from afar: lucy_terrain.avi. The movie is made from 400 frames which are exported separately as PNGs, and then converted to an avi by mencoder. Each frame took approximately one minute to render with 50 samples per pixel.