Noob question what is HD Geometry

[system]

Hello,

I am sure this has been asked a million times by noobs like me but can someone explain what HD geometry is (or provied a link) ?

I did a ZB Central forum search on the term but that did not get me any answers.

I am new to ZB coming from a polygonal and subD modelling background. When sculpting in ZB am I working with polygons?

MD

[aurick]

Yes, in ZBrush you’re working with polygons.

HD geometry is currently a ZBrush-only feature that lets you sculpt in real-time with up to 1 billion polygons. I say ZBrush-only because at this time the HD detail can only be used in ZBrush renders. It can’t be exported as a displacement or normal map. (And in fact, the idea of exporting HD as a map is problematic. After all, a 1 billion polygon model would require a 31622x316222 texture to hold all that detail – the equivalent of almost sixty 4096x4096 maps!)

http://www.pixologic.com/docs/index.php/HD_Geometry

[Maxmate]

(And in fact, the idea of exporting HD as a map is problematic. After all, a 1 billion polygon model would require a 31622x316222 texture to hold all that detail – the equivalent of almost sixty 4096x4096 maps

That’s not totally valid argument against the idea of exporting HD geometry because HD geometry is useful at lower polycounts too. Models with very small detail need 4096x4096 displacement map, if you want high resolution render that is (and who doesn’t want?!). 4096x4096 map has over 16 million pixels. It’s quite tedious to work with 16 million polygons. All operations become very slow. It would be cool if that work could be done with HD geometry cause it’s much faster than regular geometry.

[Codeman]

Im hoping that the next zb update solves the poly limit we can work with a 16 mb file without going to HD. Right now it seems Mudbox has us beat. At least from the demos I see.

[aurick]

That’s not totally valid argument against the idea of exporting HD geometry because HD geometry is useful at lower polycounts too. Models with very small detail need 4096x4096 displacement map, if you want high resolution render that is (and who doesn’t want?!). 4096x4096 map has over 16 million pixels. It’s quite tedious to work with 16 million polygons. All operations become very slow. It would be cool if that work could be done with HD geometry cause it’s much faster than regular geometry.

For typical UV layouts, a 4K map only has between 10 and 12 million pixels that are actually used. The rest is empty space. Most PC’s can handle that effectively with ZBrush 3.1. Mac users have it even easier, thanks to the ongoing optimizations which are being done (and which will become available to PC users with the next update).

I’m not saying that it wouldn’t be nice to have HD detail being able to be exported. But as a very long-time moderator of ZBC I can already see people saying, “I have 45 million polys in HD detail. Why does my map look so bad?” :)

[Maxmate]

Fortunately there is a work-around. Model that has HD geometry can be cloned in HD mode, and the clone can be used to produce displacement map. This is ofcourse possible only with realitvely low amounts of HD polys.