Multiple Fakestones, best solution?

[Mahnmut]

Hi together,
I am trying to improve my Martian desert, that means lots of stones and some dunes, something like this, only better:

https://www.flickr.com/photos/13280352@N04/14992498482/

I just wonder what the best method to combine multiple fakestone shaders is. Putting them simply one after another leads to strange intersections. Merging them one by one with merge shaders set to "highest" looks better, but increases rendertime by a faktor of nearly 4 in a simple test with 5 stone sizes. (node network attached).
Does anyone know a better method ?
I would also appreciate tips on surface displacement for fakestones and sand (tiny stones vs tiny PF).
Thanks in advance,
J

[bigben]

Sand - snow, same difference   Here's an old experiment I did with snow using the round thingies node... http://www.planetside.co.uk/forums/index.php/topic,1419.msg14142.html#msg14142 which should also work for sand.  I don't recall it having much too effect on render time and I though it looked nicer than most of the PF versions I tried. PFs also have a habit of biting you when you move around. You get it looking nice in one view and move the camera only to find something that doesn't look quite right.

[fleetwood]

In my own tests merge is very slow if you connect sequentially by adding one new layer to the sum of the previous layers.

It is much faster in processing to merge in a tree fashion. By this I mean if you start with 8 sizes of fake stones, put all 8 layers across the top level and merge them into four sub layers. Then merge those four layers into two layers and finally take those two sets of stones into one. It takes the same number of merge nodes either way but the tree method tests out to be considerably more efficient in rendering.
 

[Mahnmut]

Thanks,
thats already two helpful hints!

[bigben]

DandelO's take on sand in File Sharing
http://www.planetside.co.uk/forums/index.php/topic,11624.0.html