gvmap
Generate image map from Graphviz layout
TLDR
Generate a clustered map layout from a DOT format graph
Generate a map using existing cluster subgraphs from the input
Include graph edges in the [o]utput map
Specify a [c]olor scheme (1: pastel, 2: blue-yellow, 3: white-red, etc.)
Set the maximum number of [C]lusters (by default 0, meaning there is no limit)
Only draw cluster 2 (by default, all clusters are drawn)
SYNOPSIS
gvmap [-V] [-v] [-?] [-ooutfile] [-Tformat] [-Gattr=value] ... [-Nattr=value] ... [-Eattr=value] ... [files]
PARAMETERS
-?, -h, --help
Print usage information and exit
-V
Print version information and exit
-v
Verbose output mode
-o outfile
Write output to outfile (default stdout)
-T format
Set output format (e.g., dot, plain, canon; default dot)
-Gattr=value
Set graph attribute attr to value (e.g., -Gprojection=merc)
-Nattr=value
Set default node attribute attr to value (e.g., lat, long)
-Eattr=value
Set default edge attribute attr to value
-K engine
Use layout engine engine (ignored for gvmap; fixed to map layout)
-O
Automatically generate output filenames from input
DESCRIPTION
The gvmap command is a layout engine in the Graphviz suite designed for rendering undirected graphs embedded on a sphere, such as the Earth, using various map projections. It requires each node to have lat (latitude) and long (longitude) attributes specified as floating-point degrees. Edges are drawn as great circle arcs between nodes.
gvmap reads input graphs in DOT language format and computes node positions in a planar projection suitable for output. It supports multiple projections like orthographic (ortho), Mercator (merc), Hammer (hammer), and others. Users can customize the map bounds, dimensions, and resolution via graph attributes. The output is typically DOT format with updated pos attributes for nodes, ready for rendering with tools like dot or neato.
This engine is ideal for visualizing geographic networks, such as flight routes, telecom links, or seismic data on world maps. It handles large graphs efficiently but assumes accurate lat/long inputs.
CAVEATS
Nodes must have lat and long attributes in decimal degrees (-90 to 90, -180 to 180). Experimental engine; may not handle poles well. Undirected graphs only.
KEY GRAPH ATTRIBUTES
projection: flat|albers|azeq|azim|stereo|ortho|merc|lcc|hammer (default ortho).
bounds: "W S E N" (degrees; default world).
width, height: Output image size (inches; default 8.5x11).
EXAMPLE USAGE
echo 'graph G { a [lat=40.7,long=-74.0]; b [lat=34.0,long=-118.2]; a--b; }' | gvmap -Tplain -Gprojection=merc
Outputs node positions for Mercator projection.
HISTORY
Developed as part of Graphviz at AT&T Labs Research in the late 1990s-2000s. gvmap added around Graphviz 2.0 era for geographic visualization. Maintained in open-source Graphviz releases since 2004.
