This tool produces a polygon set from a grayscale image using halftoning.

The polygons are pixel aligned so when rendered with AGG based renderers (as well as many other rendering engines) the result will approximately match the input image being used as a coverage mask.

The output polygon grid has half the linear resolution of the input image.

The process used tries to minimize data size while maintaining consistency with the input data in terms of pixel coverage. It also tries to maintain some similarity regarding the topological configuration (as present in the double resolution input data).

Internally the tool uses some code and components from GDAL 2. To allow building it with GDAL 1 the source file gdalrasterpolygonenumerator.cpp (from GDAL 2.1.1) is included in the repository - building and linking this should only be required for GDAL 1.x

Dependecies: GDAL and CImg.

The program offers the following command line options:

• -i input image (required)
• -o output vector file (required)
• -c combined input image - to generate accurate output with several layers (optional)
• -l output layer name. Default: polygons.
• -x x attribute to apply to generated polygons (integer value, optional)
• -y y attribute to apply to generated polygons (integer value, optional)
• -z z attribute to apply to generated polygons (integer value, optional)
• -complement process complement (inverse) of input. Default: off.
• -append append to existing output file. Default: off.
• -me maximum error to accept for pixel coverage fraction. Default: 0.05.
• -debug generate additional debug output. Default: off.

##Legal stuff

This program is licensed under the GNU GPL version 3.

Copyright 2016 Christoph Hormann