yeah, thats the way i'm searching for shadow pixels (actually i use sun_pos.x instead of calculating the position for myself). The engine places the Vector sun_pos 1 million (!!!) quants outside of the point of origin (compared to 10.000 quants in your code example).

Actually I'm a bit irritated, because a terrain is about 100-500 quants big, therefore these quants should really be not important compared to the 1 million quants distance to the terrain (at least from the mathematical point of view..)

Addionally the shadow has the same length for all models, no matter where they are on the terrain. Only self shadowing makes a "shorter" shadow.
Sadly i have no idea why.. :X