maptrace

Produce watertight polygonal vector maps by tracing raster images.

• THIS IS NOT A GIS TOOL (the output is not georeferenced)

• DO NOT USE THIS TOOL TO CIRCUMVENT COPYRIGHT RESTRICTIONS ON EXISTING MAPS (you will be judged in the next life)

• DO NOT USE THIS TOOL ON MULTI-MEGAPIXEL IMAGES (because loops are really slow in Python)

On the other hand, it might come in handy to generate crisp display images for presentations/articles from raster images you created yourself.

• Python 3
• Pillow 8.3.1 or higher
• Numpy 1.24 or higher
• Scipy 1.9 or higher
• Scikit-image 0.19.0 or higher

The files in the images directory are licensed as follows:

• pa-2012-pres.png [source], license CC-BY-SA 3.0

• pa-counties.png [source], license CC-BY-SA 2.5

• birds-head.png adapted by E. Gasser from an unpublished map by sil.org, all rights reserved

Maps created by maptrace.py from these input images (including the respective outputs in the examples directory) shall be considered derivative works for copyright purposes.

The images in the examples directory were created by running the following commands:

python maptrace.py -c images/pa-2012-pres.png -f open:cross,1 -n2
python maptrace.py images/pa-counties.png -m 1000 -e1.42 -n4 -b4
python maptrace.py -c images/birds-head.png -C8 -m40 -n8 -q5 -s8 -b16 -f dilate:box,2

(The last command might take a few minutes.)

The maptrace.py program itself is provided under the MIT license.