shadows in raytrace too dark

[Dean]

Have you tried using low or medium radiosity? this will allow some diffused light to fill in those shaded areas and bring out the detail there.

Increasing the sunlight power and increasing the diffuse sunlight power will also help.

You can also increase the diffuse setting on the materials that are in the shadows and the terrain material as well. Somewhere around medium could make those shade areas react more to the radiosity
lighting effects.