Multi-Scale 3D Gaussian Splatting for Anti-Aliased Rendering

3D Gaussians have recently emerged as a highly efficient representation for 3D reconstruction and rendering. Despite its high rendering quality and speed at high resolutions, they both deteriorate drastically when rendered at lower resolutions or from far away camera position. During low resolution or far away rendering, the pixel size of the image can fall below the Nyquist frequency compared to the screen size of each splatted 3D Gaussian and leads to aliasing effect. The rendering is also drastically slowed down by the sequential alpha blending of more splatted Gaussians per pixel. To address these issues, we propose a multi-scale 3D Gaussian splatting algorithm, which maintains Gaussians at different scales to represent the same scene. Higher-resolution images are rendered with more small Gaussians, and lower-resolution images are rendered with fewer larger Gaussians. With similar training time, our algorithm can achieve 13\%-66\% PSNR and 160\%-2400\% rendering speed improvement at 4$\times$-128$\times$ scale rendering on Mip-NeRF360 dataset compared to the single scale 3D Gaussian splatting

A Bis-benzopyrroloisoquinoline Alkaloid Incorporating a Cyclobutane Core and a Chlorophenanthroindolizidine Alkaloid with Cytotoxic Activity from <i>Ficus fistulosa</i> var. <i>tengerensis</i>

Tengerensine (<b>1</b>), isolated as a racemate and constituted from a pair of bis-benzopyrroloisoquinoline enantiomers, and tengechlorenine (<b>2</b>), purified as a scalemic mixture and constituted from a pair of chlorinated phenanthroindolizidine enantiomers, were isolated from the leaves of <i>Ficus fistulosa</i> var. <i>tengerensis</i>, along with three other known alkaloids. The structures of <b>1</b> and <b>2</b> were determined by spectroscopic data interpretation and X-ray diffraction analysis. The enantiomers of <b>1</b> were separated by chiral-phase HPLC, and the absolute configurations of (+)-<b>1</b> and (−)-<b>1</b> were established via experimental and calculated ECD data. Compound <b>1</b> is notable in being a rare unsymmetrical cyclobutane adduct and is the first example of a dimeric benzopyrroloisoquinoline alkaloid, while compound <b>2</b> represents the first naturally occurring halogenated phenanthroindolizidine alkaloid. Compound (+)-<b>1</b> displayed a selective in vitro cytotoxic effect against MDA-MB-468 cells (IC₅₀ 7.4 μM), while compound <b>2</b> showed pronounced in vitro cytotoxic activity against all three breast cancer cell lines tested (MDA-MB-468, MDA-MB-231, and MCF7; IC₅₀ values of 0.038–0.91 μM)