Vegetation : Alpha (8 bits), Stencil (2 bits), or full geomtry ?

[paq]

Hello,

Having used many render engine so far, they all have a 'prefered' method when it's about rendering leaves and the like.
I'm not really sure what terragen prefer, I suspect full geometry leaves would be the best choice ? (accrording you have plenty of memory)

[Oshyan]

Full geometry is certainly best for highest quality results, but 8 bit alpha also works fine. If you can, do full geometry for close-up "hero" trees at least.

- Oshyan

[Matt]

I think you're referring to the fact that some renderers are especially fast at rendering many overlapping alpha-mapped planes, while for others it's just faster to use high-res geometry without alphas? I haven't really done speed comparisons in Terragen, but I know there's a substantial overhead every time it traces a new ray and calls shaders to determine opacity, which it has to do more times per pixel when there are many overlapping transparent surfaces. So in Terragen it's very likely that high-res geometry will render faster than low-poly alpha-mapped objects (assuming you don't go over your physical RAM limit). I'd be interested in other opinions from users though.

Regarding 8-bit alpha vs. 1-bit stencil, currently Terragen turns all 8-bit opacity maps into a 1-bit yes/no transparency (after interpolating the pixels), but in future it will probably use the full range.

Matt

[paq]

Hello Oshyan and Matt,

Thanks for the reply.

Hi Matt,

Yes it was exactly my concern, some renderer slow down a lot when lots of transparency materials are overlapping (Vray, Vue).
Looks like Terra handle insane polycount tree very well, so I will go that way

[TheBadger]

For me,  my high polly objects render faster. But can slow working down, up to render time. Never did a simple clock test to prove it though, so just anecdotal.

[Walli]

of course it always boild down to the render engines and the render (and GI) settings. But I found that most applications that handle memory well, work fine with high poly plants and that a highpoly approach often renders fastr compared to models with tons of overlapping alpha maps.
I found TG to handle highpoly plants very well.

By the way - high poly plants also often use alpha channels, but if you use such plants in the midground, you often can turn off the bitmaps and just render the geometry - so you have the best of both worlds ;-)

[bobbystahr]

that verities what I thought I'd noticed using your Medium Hazel Walli, which has both options...thanks for the confirmation...