PolarTransform maps Cartesian ↔ polar, enabling radial edits, cat’s eye bokeh and Petzval-type lenses, high-fidelity resampling, and seam-free polar transformations.
Polar Transform
First submitted: 8 February 2026
Author: Marty Blumen
Website: https://www.martyblumen.com/
Compatible Nuke versions: 13.1 or later
Compatibility: Windows
PolarTransform: Technical & Artist Overview
PolarTransform is a high-fidelity coordinate-space operator mapping between Cartesian (x, y) and polar (r, θ) coordinates. By linearizing rotational structure, it allows blurs, transforms, and procedural modulation to act radially or angularly without per-pixel rotations or repeated resampling. Both unwrap (Rect → Polar) and restore (Polar → Rect) modes are supported, with radius normalization. Optional Fix Seam adds padding and wrap-around sampling to maintain continuity at the angular seam.
The transformation introduces non-uniform sampling density near the pole. To minimize aliasing and preserve detail, the node offers Nearest, Bilinear, Bicubic (Catmull-Rom), and 8×8-tap Lanczos-windowed sinc (64 samples per pixel) filters. Implemented in BlinkScript with GPU acceleration, it computes inverse mappings, clamps edges, and applies seam-fixing padding to avoid foldover artifacts. Mild ringing may appear near high-contrast edges. Currently, only RGBA channels are processed; additional passes are needed for depth, motion, or AOVs.
Artist Usage:
Use PolarTransform to unwrap circular highlights for creating cat’s eye bokeh effects. In the polar domain, you can stretch, distort, or stylize highlights and radial elements before restoring them to Cartesian space. The Fix Seam option ensures smooth continuity across the angular wrap, preventing visible seams. This workflow allows predictable, high-quality radial edits without introducing geometric distortion or sampling artifacts.
SD 3-Clause License
Copyright (c) 2026, Marten Blumen
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