raycast2D

raycast2D is a fast, single-thread 2D raycasting implementation written in C with a small Python API. It operates on NumPy occupancy grids / binary images (free cells are non-zero; occupied cells are 0) and computes ray intersections using Bresenham line algorithm.

The core package depends only on numpy.

Installation & Usage

$ pip install raycast2D

Basic cast function usage

import numpy as np
from PIL import Image
from raycast2D import cast

img = Image.open("<path/to/img.png>")
img_array = np.array(img)[:, :, 0] # Use single channel
pose = (250, 250, 0.5)  # x, y, yaw in radians 

rays = cast(img_array, pose, num_rays=360, ray_length=500)

print(rays[:5])
# Expected output (example):
# [[x0 y0]
#  [x1 y1]
#  [x2 y2]
#  [x3 y3]
#  [x4 y4]]

Using the Lidar2D class

from raycast2D import Lidar2D
# [...] 
lidar = Lidar2D(num_rays=360, FOV=360, ray_length=500)
lidar.set_map(img_array)

rays = lidar.scan((250, 250, 0.5))

print(rays[:5])
# same output as before...

Plotting example

import numpy as np
import matplotlib.pyplot as plt
from PIL import Image
from raycast2D import cast

img = Image.open("media/lab_intel.png")
img_array = np.array(img)[:, :, 0] # Use single channel

pose = (350, 350, -1.0)
rays = cast(img_array, pose=pose, num_rays=200, FOV=90, ray_length=250)

plt.imshow(img_array, cmap="gray")
plt.scatter([pose[0]], [pose[1]], c="green", s=10)
plt.scatter(rays[:, 0], rays[:, 1], c="blue", s=1)
for ray in rays:
    plt.plot([pose[0], ray[0]], [pose[1], ray[1]], c="red", linewidth=0.5, alpha=0.3)
plt.show()

Performance

The benchmark script in test/benchmark.py runs a small set of examples and prints throughput in rays/s. Example results (tested on an i7-9700k):

Map size	Ray length	Rays per call	Mean time (ms)	Throughput (rays/s)
512×512	2000px	5000	0.2490	20,083,924
4096×4096	2000px	5000	0.2848	17,556,549
8192×8192	2000px	5000	0.2571	19,446,324

To reproduce on your machine:

$ python3 test/benchmark.py

Interactive demo

The repository includes an interactive pygame demo that raycasts from the current mouse position.

$ pip install "raycast2D[extra]"
$ python3 test/demo.py

Testing and development

Install the test/development dependencies:

$ pip install "raycast2D[test]"

Run the test suite with:

pytest

License

GPL-3.0-only. See LICENSE.