SIGNED-DISTANCE-FIELD-RS

Fast Signed Distance Fields for Rust

This crate approximates a signed distance field, given a binary image. The algorithm is inspired by the paper "The dead reckoning signed distance transform" by George J. Grevara (2004).

On my laptop, the distance field of an image with 4096px x 4096px (16 Megapixels) containing a circle with radius of 6px in the center can be computed in about 0.927 seconds.

Features

In the process of computing the signed distance field, the algorithm constructs an image with each pixel containing the vectors which point to the nearest edge. This vector distance field is made available after computing the plain distance field and can be used for further processing. Also, the library offers a simple conversion from distance fields to images with integer precision.

Getting Started

Update your Cargo.toml:

signed-distance-field = "0.6.2"

Use compute_f32_distance_field to compute a distance field with f32 precision and memory usage.

use signed_distance_field::prelude::*;
    
fn main(){
    let mut gray_image = image::open("images/sketch.jpg").unwrap().to_luma();
    let binary_image = binary_piston_image::of_gray_u8_image_with_threshold(&gray_image, 80);

    let distance_field = compute_f32_distance_field(&binary_image);
    let distance_image = distance_field.normalize_distances().unwrap().to_gray_u8_image();

    distance_image.save("images/sketch_distance.png").unwrap();
}

To run this specific example, the piston_image feature flag must be enabled.

Piston Images

This library can be configured to offer some simple conversions to and from piston images. The feature flag piston_image unlocks these functions. The image crate is not required to calculate the signed distance field.