half precision attributes

[danw]

Hi all,

Searched around, and can't find any mention of this.

I'm working on some very high particle count fluid data, and it's taking a lot of space. Now position might need full floating point precision, but velocity vectors, normal vectors, and point scale attributes would work perfectly well with half-precision data types. Is this possible in Houdini? Can I specify half precision attributes, or even work with full precision and recast them when writing .bgeo files?

[symek]

Very interesting topic indeed. Specially that many new techniques demand double precision attributes, which slowly becomes a must in 3d. It would be great to be able to trade off precision/memory/storage per attribute in geometry.

AFAIK Houdini lets you specify data type only for volume primitives. Besides that an attribute class rely on HDK specification which is constant type per attribute: HDK Docs. This may change though, as birds sing about new geometry engine coming really soon and some hdk enumerator mentions half type also.

Edited November 22, 2010 by SYmek

[Nerox]

as birds sing about...

Ghehe, how romantic . (SYmek you've got a gift! I wasn't aware of any romance in volume primitives, HDK and double precision attributes)

[Macha]

I don't know if this helps but the Timeblend node has now an option that takes attributes into account. So, you could get the correct motionvector pass even without attaching velocity and get rid of it altogether, even with changing pointcount.

Not sure that would render faster though.

Or, change them to integers. Perhaps we can scale them back in post or in a shader during rendertime.

Edited November 22, 2010 by Macha