ERRATA Correction: In our paper we write about [Gum03] that its "bounding box computation is only correct for orthogonal projections, and thus might clip or cut off ellipsoids for perspective ones." This statement is incorrect. The method by [Gum03] DOES NOT compute an axis-parallel bounding box and it DOES NOT cut off ellipsoids. It rather computes a correct, perspectively distorted, general bounding quadrilateral that contains the silhouette ellipse in world space. The resulting quadrilateral is a tight enclosure, but in contrast to our method it requires four times as many vertices per splatted quadric. Our proposed rendering method uses only a single GL_POINT primitive for each splatted quadric, requiring an axis-aligned bounding box to determine the respective point size. Deriving such a bounding box from the general quadrilateral bounding shape of [Gum03] would be non-trivial, as perspective distortion has to be accounted for. The bounding box of the quadrilateral itself, however, would be an overly conservative estimation. Consequently, we had to develop a novel bounding box computation. Additional reference: Please note that our paper also relates to the following publication: G. Reina and T. Ertl. "Hardware-Accelerated Glyphs for Mono- and Dipoles in Molecular Dynamics Visualization". In Proceedings of EUROGRAPHICS - IEEE VGTC Symposium on Visualization 2005, pp. 177--182. The respective paper presents a molecule visualization system similar to ours. It also employs point sprites, vertex, and fragment programs to raycast perspectively correct spheres and cylinders. The presented system supports depth cues and adaptive rendering. Point sizes are computed using an unspecified heuristic.