Some fractal terrain questions

[waldronate]

Thanks , here another small problem , I applied the heightfield computation noise in a selection with a feather of 2 ...
but it affecs also the outside ...

The changed values are :

size x y z 222 for all and no spherical evaluation , operation type set to multiply and size to 150

The dashed line showing the edge of a selection is the mid-point of the selection values. If we assume that a selection's intensity ranges from 0 (0%=no effect) to 255 (100%=full effect), then the dashed line shows at the place where the selection is 127 (50%). That means that even though your selection may show just a tiny area selected, there may still be parts that can receive up to half of the effect. In Photoshop, there is a warning if there are no pixels in the selection that cross the edge threshold; Wilbur doesn't have the warning. Wilbur also doesn't have the feature that allows you to view the selection as a color on top of the main image (Quick Mask).

about the above description of the erosion , I am not sure I understood the meaning of :

how to make it more deep carving?

With the precipiton erosion, what you get in a pass is what you get. If you're doing multiple passes, setting the Blend amount to greater than 100% will give more weight to the newly-eroded terrain when blending, but strange artifacts appear. Using Edit>>Fade to Prior with a value less than -1 will also give interesting effect, but cause strange artifacting. The incise flow operation is controllable, but the precipton one is much less so.