Geoc: Canvas Based Geographic Rendering

geocanvas image

Geoc aims to provide a very small and simple set of API's to assist the developer in creating geographically referenced canvas applications within the GTK-2 environment.

Geocvpf is an additional library that is used to render Vector Product Format including Digitial Nautical Charts.

The geoc library is built on crcanvas. The API is a simplified and reduced version of the original geocanvas API. Performance in some cases can be worse than with geocanvas due to differences in the underlying rendering libraries. The packages include a GeocLinesFaster canvas item that paints using GDK drawing commands instead of Cairo which can bring it back to geocanvas levels when it is necessary to draw lots of polygons.

geoc features

  • Complete GObject developer interface hides low level interaction.
  • Automatic viewport and scroll region management.
  • Common interface routines for construction of poly and point objects.
  • Properties set on parent automatically passed to child items.
  • Complete Python language bindings.
  • Download geoc. (geoc depends on crcanvas)

    API Reference

    Example Code and Introduction

    View Python Example Program (included in package)


    geocvpf image

    Geovpf provides a GObject interface that is used to plot Vector Product Format (VPF) onto the GeocCanvas. VPF is a geo-relational format developed by the National Geospatial Intelligence Agency. It is specified by MIL STD MIL-STD-600006. VPF is the format used in Digital Nautical Charts.

    geovpf features

  • Plots VPF directly without conversion to intermediate datasets.
  • Supports thematic display and limited expression queries.
  • Optional automatic library selection mechanism based on current viewport.
  • Complete Python language bindings.
  • Download geocvpf. (geocvpf depends on geoc and crcanvas)

    API reference

    Example Code and Introduction


    This library uses some of the original vpfview source code. The vpfview source is available in its entirety at There is also a working binary available for Windows systems at the same site.