Billboarding/impostors mean, roughly, representing complex 3D objects in 2D or with simple quadrilaterals, for the sake of LOD systems.

Consider the case of rendering a very numerous asteroid field where one base asteroid mesh is instanced X times. If none of the instances of the mesh are re-scaled, it is easy to replace them with a billboard/impostor: one should just generate a billboard or impostor for the base asteroid mesh and substitute each asteroid instance with an instance of the billboard/impostor when desired.

Now, if each instance of the asteroid mesh that is present in the asteroid field is supposed to be re-scaled (e.g. to give the illusion of diversity to an asteroid field), this becomes much more complicated. Re-scaling a billboard quad of the base asteroid mesh, for instance, would not mimic the re-scaled instances of the asteroid mesh. At the same time, it is not clear whether using techniques like true-impostor would solve that any further.

Thus, my question is: is there any impostoring technique that would allow that? I.e. pre-generating an impostor of the base asteroid mesh, then scaling each impostor's instance in a way that would mimic the re-scaling of the instances of the asteroid mesh?

I have been reading the recent literature on advanced billboarding/impostor techniques (true impostors, 3-view impostors, volumetric impostors, etc), but I am still confused about that.

  • $\begingroup$ Why would scaling the billboard quad not mimic the appearance of scaling the asteroid mesh? If they're far away enough to use billboards in the first place, that should work fine, unless I'm missing something. $\endgroup$ – Nathan Reed Jul 31 '16 at 16:37
  • $\begingroup$ Are you concerned about scaling up a billboard to the point that it requires a different level of detail? $\endgroup$ – trichoplax Jul 31 '16 at 19:56