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DOI

py-microdots

This repository provides py-microdots, a Python library for encoding and decoding 2D locations based on the Anoto dot pattern approach.

The Anoto grid pattern encodes a unique 2D position for every possible 6x6 sub-array of dots. Assuming a grid resolution of 0.3 mm, this coding remains unique over the area of Europe and Asia. For clarity, the dots are significantly scaled up and nominal grid lines are shown.

Paper / Cite

This implementation is based on my personal research on the Anoto coding. My findings are published in the following paper

@InProceedings{cheind2023microdots,
  author="Heindl, Christoph",
  title="py-microdots: Position Encoding in the Euclidean Plane Based on the Anoto Codec",
  booktitle="Intelligent Computing. Computing Conference SAI",
  year="2023",
  publisher="Springer Nature Switzerland",
  pages="219--235",
  isbn="978-3-031-37963-5"
}

A pre-print of the report is available here.

Features

py-microdots offers the following features

  • Decoding of position coordinates, section coordinates and pattern rotations.
  • Encoding support including section coordinates
  • Drawing routines
  • Generalized interface that supports tailored coding variants (e.g. 4x4 codes)

Scope

The focus of this library is depicted in the following diagram

py-microdots focuses on encoding and decoding of bit-matrices and does not come with image processing or plotting capabilites.

Example

# Import the library
import microdots as mdots

# Use the default embodiment with A4 sequence fixed (see paper)
codec = mdots.anoto_6x6_a4_fixed

# Generate a bit-matrix for section (10,2)
G = codec.encode_bitmatrix(shape=(9, 16), section=(10, 2))

# Render dots
import matplotlib.pyplot as plt

fig, ax = plt.subplots()
mdots.draw_dots(G, grid_size=1.0, show_grid=True, ax=ax)
fig.savefig("dots.pdf")
plt.close(fig)

# Decode a partial matrix
S = G[3 : 3 + 6, 7 : 7 + 6]

pos = codec.decode_position(S)
sec = codec.decode_section(S, pos=pos)

# To decode the rotation, use an extended matrix
R = G[3 : 3 + 8, 7 : 7 + 8]
rot = codec.decode_rotation(R)
print("pos:", pos, "sec:", sec, "rot:", rot)
# > pos: (7, 3) sec: (10, 2) rot: 0