  3D Gaussian Splatting (3DGS) has shown remarkable success in synthesizing
novel views given multiple views of a static scene. Yet, 3DGS faces challenges
when applied to dynamic scenes because 3D Gaussian parameters need to be
updated per timestep, requiring a large amount of memory and at least a dozen
observations per timestep. To address these limitations, we present a compact
dynamic 3D Gaussian representation that models positions and rotations as
functions of time with a few parameter approximations while keeping other
properties of 3DGS including scale, color and opacity invariant. Our method can
dramatically reduce memory usage and relax a strict multi-view assumption. In
our experiments on monocular and multi-view scenarios, we show that our method
not only matches state-of-the-art methods, often linked with slower rendering
speeds, in terms of high rendering quality but also significantly surpasses
them by achieving a rendering speed of $118$ frames per second (FPS) at a
resolution of 1,352$\times$1,014 on a single GPU.
