Hi All, im the happy owner of a copy of houdini indie

motivated to purchase because i need some sand, and finally an excuse to force myself to learn some more H.

anyway, started with the wet sand shelf tool.. in the end i wish to show a plant sprouting from the ground.

all i did was to decrease the particle radius to increase the detail, and turned up the clumping, as i noticed that when you increase the res, the clumping gets less noticeable. i want some serious clumping, as in the end it should look more like earth than sand.

i also added an alembic rop output, and exported to 3dsmax/vray for rendering. i used the vraypointparticle shader, and the vrayparticlecolor to use the colours from the alembic.

worked ok, kinda.

here is a link to my render:

http://we.tl/fwDlvNtkTU [we.tl]

as you can see, two major issues..

one: the sand collapses when it hits the ground plane before rebounding.

this didnt happen at a lower resolution.

two, whats up with the particle shading? seems to lose the colour attribute after a certain period.

three, what are sensible values for clumping if i want some really large clumping going on, and is there a ratio i can use when changing sim res to keep clumping behaviour similar?

finally, for that sim, the alembic was 73 gb for 200 frames. any compression tricks i can use?





thanks, to all. Robin.

ignore the red colour..id been playing with particle sleep and forgotten to disable.

other questions still stand..

nobody? im having a lot of problems with “bouncy” sand. the moment i decrease the particle size from default things get springy.

when i drop sand onto a plane, it tends to collapse a bit then spring back.. the thicker the sand the more extreme it is.
most unrealistic.

just a few pointers which settings to look at, or even good tutorials would be most appreciated.

id imagine there is a fairly standard workflow for changing sim detail, as people must do it every time they do a sim.

http://www.sidefx.com/docs/houdini15.0/grains/change [sidefx.com]

Some bits in there that look like they can address your basic issues:

“Increase the Shock Scaling Power on the POP Grains node to tame the initial bounce and create fluffier piles that almost look like snow.”

“Increase iterations. However, more iterations will make your simulation slower.”

“Turning off Enable Mass-Shock Scaling will also reduce the bounce, since the higher particles are heavier and won’t move as much on the second frame, but your piles will lose stability. ”

I'd obviously careful with that last one and try playing around with the first and second before that.

Thanks for the reply. That all seems clearer now. Somehow i missed the bit about bouncy particles when i read that page previously.

I apologise i have just realised i posted in the wrong forum too. D'oh.