Quote Originally Posted by Aidan View Post
Okay, I got past that problem. I was using a lower blur on my landmasses, because I had a fairly detailed coastline. The noise layer was just having a very small effect. I'm probably using this technique on a scale it's not meant for.

I'm pretty pleased with the results so far, but have bogged down at the rivers stage now. When I draw lines in black on the grass mask, it makes the rivers almost white, the lightest water color, which is the color from the layer that I used for the shorelines.

I'd attach my xcf file, but even zipped it's over 7 meg. Here's a jpg of the results though.
I had the same problem (with regards to the continent outline). There's a certain level of detail for which this technique will not produce satisfactoricaly fractalized-looking coasts. You have to be willing to sacrifice a lot to the blur to make it work.

With regards to the river, if I recall the way the tut works, you're basically masking out part of the land to expose the underlying water color, But since the color that lies directly below the continents is the almost-white shoreline color, your rivers will look almsot-white, too.

If I'm recalling correctly then here's one potential solution: with your land showing, and your rivers already masked out, add a new layer between your lowest land and your topmost ocean layer. On this new layer (call it river color, or something) with a thin soft brush set on an intermediate blue value paint along the lines of the rivers. Play with different brushes and different layer settings to get the blend with the shoreline blue-white layer looking right. (I suggest leaving both your land layers and ocean layers showing so you can see the effect of the work as you paint.)