Rolling hills or sand dunes with shear cliffs, sharp drop offs

Geology and Terrain
#1

I found an earlier post about this http://forum.world-machine.com/index.php?topic=1617.0 and I’m trying to achieve the same shape, but the solution was to apply this to one “mountain”.

I’m looking to do this for an entire map on a bunch of rolling hills or sand dunes that have shear cliffs or sharp falloffs on one side.

Any suggestions on how to do this? I can get the rolling hills look and the sand dunes, I’m having a hard time getting that sharp falloff on the one side of it.

Heres a couple of pics of what I’m trying to achieve:
http://www.mccullagh.org/db9/1ds-4/tunisia-sand-dunes-sahara.jpg
http://homepages.nildram.co.uk/~likeman/fhionnlaidh/45.JPG
http://i33.tinypic.com/351vjih.jpg
http://upload.wikimedia.org/wikipedia/commons/5/50/Quiraing,_Isle_of_Skye.jpg

Thanks!

#2

To simulate asymmetric sand dunes, My favorite go-to technique is to use an “Angle Selector” piped into a Snow device. Despite being named “snow”, it can also model accumulations of sand quite convincingly; the sharp spiky tops won’t be present on the dunes, but you can use it to accumulate a layer of sand/soil on one side only of the underlying rocks.

By piping your mask into the “intensity” input, and turning the evaporation balance to zero, you can make the snow behave more like sand, and make it accumulate and flow on only one side of the rocks.

A last bit of advice when using this technique is to blur either the input or output of your angle selector to make sure the transitions are sufficiently smooth.

#3

I have some tutorials how to do that at www.geekatplay.com here is few images from this tut:

dunes1.jpg960×332

and
dunesx2.jpg2000×693

#4

Thanks Stephen and Geekatplay.

I’ll mess around with your suggestions and I’ll see what I can come up with.

#5

This looks so freaking sweet!!!

#6

oqisoje@ser.namnerbca.com

#7

amoluhu@mailer.namnerbca.com

#8

opoqude@mailer.namnerbca.com

#9