[Bf-committers] Adaptive subdiv modifier

Sergey Sharybin sergey.vfx at gmail.com
Wed Oct 29 12:39:40 CET 2014


The idea is quite interesting, however here're the issues:

- It makes more sense to do feature-adaptive subdivisions, not
camera-space-adaptive one. Camera space you can kind of fake now using a
driver on the subdivisions level slider.
- Doing adaptive subdivisions would likely mean texture flickering in the
animation. To prevent this Ptex is usually used instead of UVs.
- The code ideally should work or multires as well (it's the same
underneath code actually), and this i'm not sure how is gonna to work.

The biggest issue with your proposal is -- we've got ongoing branch called
opensubdiv-modifier [1], where we basically integrating OpenSubdiv into
blender. And OSD already supports both feature and camera space adaptive

For sure your help on finishing that branch is welcome.

[1] https://developer.blender.org/diffusion/B/browse/opensubdiv-modifier/

On Thu, Oct 23, 2014 at 7:49 PM, Patrice <patrice.bertrand.eu at gmail.com>

> This was meant to be a new thread, so I repost, sorry.
> Hello,
> An idea that I wish to share here:   a new option of the subdiv modifier
> where subdivisions level would depend on distance from scene camera.
> In a scene, objects may be near or far, sometimes the whole tea-cup may
> be so far away it's just a few pixels high, sometimes it's a closeup
> shot, or it may start near and big, then end up far and tiny later in
> the scene.   Clearly there is no use in having a 4 level SS when it all
> ends up 10 pixels high, but one cannot adjust settings for every
> shot.    It would not be very difficult to have the SS modifier first
> calculate the final pixel size of the whole object, then adjust the SS
> level accordingly.   This behaviour could be set at the SS modifier
> level, or better yet at the scene level, together with the "simplify"
> panel.
> Has this been considered before ?   Is it maybe not far from what the
> open subdiv integration will do ?    Do you see any difficulty ?
> One that I can imagine is the case of large objects with some part of
> the mesh near the camera, others further.    Ideally, the SS would adapt
> the level to the distance of each face, but this would be far more
> complicated, and maybe would be exactly what open subdiv does.   Short
> of this, it could simply consider the nearest distance between mesh and
> camera, and base the SS level on this distance.
> Patrice.
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With best regards, Sergey Sharybin

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