HeadlinesBriefing favicon HeadlinesBriefing.com

Ultra-Compact SVG Plots via Orthogonal Distance Fitting

Towards Data Science •
×

Generating high-fidelity vector graphics often results in bloated SVG files because tools like Matplotlib default to using many short, piecewise linear segments to approximate smooth functions. A new approach detailed in Towards Data Science leverages cubic Bézier curves, achieving visual equivalence with far fewer geometrical instructions. This technique targets the core inefficiency in current vector rendering practices for complex mathematical plots.

This process relies on the Orthogonal Distance Fitting (ODF) algorithm, building upon prior work by Alvin Penner. First, the target function is approximated using a Chebyshev series, which converges much faster than standard piecewise interpolation methods. A trust-region optimizer then iteratively fits cubic Bézier curves to minimize the maximum orthogonal distance error against this high-accuracy proxy.

For example, approximating the function $f(t) = exp(-t)cos(-2pi t)$ previously required 250 segments in the standard approach. Using ODF, the same visual quality is achieved with just 8 Bézier segments. The open-source Python package `bbai` implements this fitting routine, allowing developers to generate remarkably small yet visually perfect SVG outputs directly for web use.

This method fundamentally changes how visualization libraries can represent continuous data in a scalable vector format. By replacing numerous linear approximations with a handful of precisely calculated parametric curves, file size reduction becomes substantial without introducing any visual artifacts upon scaling.