Nice tutorial, thanks. I recently discovered this site and I've been excitedly playing with the tutorials here. I was following this one, trying to create a mountain range for a map I had planned, and ran into a problem.
I had several ridges close to each other in my height map sketch I started with:
Applying this method directly yielded an alienistic landscape with very smooth crater-like valleys between the ridges. This was generated using Photoshop's lighting effects rather than Bryce.
I think this is due to the dilate process used with the selection contract tool. Realistic earthlike mountains have valleys that are actually surprisingly sharp (check google maps satellite images).
The method I discovered after much button pressing was to alter the following steps:
1) After you have the contracted selection, save it as a channel.
2) Load the channel you started the contract from. Invert selection (Ctrl-shift-I) and repeat the contract operation. Save this as a channel as well.
3) Create a new channel, fill with 50% gray. Load the selection from the channel created in 1) above, and fill with white. Load the selection from the channel created in 2) above, and fill with black.
4) Continue with the process, using this latest channel as the one you use for further steps.
With this, I came up with something that had way better valleys. A sample is below. I hacked this up very quickly for this post to keep it clear. To get nice ridges for high mountains, you need to pay more attention to getting a better initial sketch or do some magic with curves and such.