meteorite generator

↻ 2025-12-18

Procedural Meteorite Pattern Generator

I keep the repo here up to date.

This project generates large-format, purely vector, procedurally generated meteorite-like surface patterns and outputs them as PDF files suitable for print, CNC, laser, or further vector processing.

The algorithm was developed by studying a slice of the Muonionalusta meteorite, discovered in northern Sweden in 1906. Muonionalusta is an iron-nickel meteorite that exhibits a Widmanstätten pattern when etched, revealing interlocking crystalline phases formed by extremely slow cooling over millions of years.

This generator models the statistical and structural properties visible in etched meteorite slices:

• dominant crystallographic directions
• layered cross-hatching
• imperfect, double-etched strokes
• missing material and discontinuities
• large-scale grain regions with local variation

The result is a pattern that looks geologic and crystalline rather than decorative or algorithmic.

Output Characteristics

• Arbitrary size PDF (limited only by memory/time)
• No rasterization, no textures, no images
• Every run produces a unique pattern by default
• Optional deterministic regeneration via seed

High-Level Method

The image is synthesized as the superposition of several independent line families, each representing a dominant crystallographic direction.

Each family is generated using the following components:

1. Directional Angle Mixture

A small set of dominant line orientations is defined (e.g. ~45°, ~135°, minor orthogonal components).\ Each stroke family samples from a weighted angular distribution with tight variance, producing strong directional bias without mechanical regularity.

2. Parallel Stroke Fields

For each direction: an infinite set of nearly parallel lines is generated, spacing is randomized using a log-normal distribution, lines overshoot the page and are clipped implicitly

This mimics the irregular lamella spacing seen in etched iron-nickel alloys.

3. Grain Modulation Field

A low-frequency fractal noise field (FBM over value noise) is evaluated across the surface.

This grain field modulates: stroke width, stroke opacity, dropout probability, ghost-stroke offsets

This produces large-scale “crystal regions” where texture coherently shifts.

4. Stroke Imperfection

No line is perfectly straight: lateral jitter is applied along the normal direction, and jitter is smooth, not noisy, to avoid cartoon effects. Additional “ghost strokes” are drawn nearby to simulate double-etching

5. Material Loss / Etch Gaps

Segments of strokes are randomly dropped based on local grain intensity, producing: broken lines, etched voids, and discontinuities characteristic of physical material removal

Randomness and Reproducibility

By default: Each run uses a cryptographically strong random seed. You will never get the same output twice unless you use the same seed.

For reproducibility: You may supply an explicit seed. The seed used is printed after generation. Reusing the seed reproduces the pattern exactly

File Naming

Generated PDFs are automatically timestamped using UTC:

meteorite-YYYY-MM-DD-HH-MM-SS.SS.pdf

Example:

meteorite-2025-12-18-14-03-22.17.pdf

Usage

Install dependencies

pip install reportlab

Generate a pattern

python meteorite.py

The script will: generate a new, unique pattern, write a timestamped PDF, print the output path and seed.

Deterministic regeneration

generate_meteorite_pdf(
    W=3000,
    H=1800,
    seed=123456789
)

Coordinate System and Scale

PDF units are points (1/72 inch), but since the output is vector, you may treat units as arbitrary.

For example: - 36×24 inches → 2592×1728 points - Large architectural panels are feasible

home | about | github | mastodon