The Geospatial Data Abstraction Library (GDAL) is a unifying C/C++ API for accessing raster geospatial data, and currently includes formats like GeoTIFF, Erdas Imagine, Arc/Info Binary, CEOS, DTED, GXF, and SDTS. It is intended to provide efficient access, suitable for use in viewer applications, and also attempts to preserve coordinate systems and metadata. Python, C, and C++ interfaces are available.
libgeotiff is a library (normally built on top of libtiff) for reading and writing coordinate system information from/to GeoTIFF files. It includes CSV files for expanding projected coordinate system codes into full projections definitions and examples of transforming the definitions into a form that can be used with the PROJ.4 projections library. It also includes the sample applications listgeo (for dumping GeoTIFF information in readable form) and geotifcp (for applying geotiff tags to an existing TIFF or GeoTIFF file).
libtiff provides support for the Tag Image File Format (TIFF), a widely used format for storing image data. The latest version of the TIFF specification is available on-line in several different formats, as are a number of TIFF Technical Notes (TTN's). Included in this software distribution is a library, libtiff, for reading and writing TIFF, a small collection of tools for doing simple manipulations of TIFF images on UNIX systems, and documentation on the library and tools. A small assortment of TIFF-related software for UNIX that has been contributed by others is also included. The library, along with associated tool programs, should handle most of your needs for reading and writing TIFF images on 32- and 64-bit machines.
OpenEV is a library and reference application for viewing and analysing raster and vector geospatial data. OpenEV capabilities include the following: handling of raster and vector data, support for 2D and 3D display, graceful handling of very large (gigabyte) raster datasets, support for multi-channel raster datasets, understanding and interpreting of georeferencing information, pan/zoom/rotate at interactive frame rates (using OpenGL), and a powerful image analysis tool (using Numerical Python).
PROJ.4 is a cartographic projections and datum shifting library written in C. It includes support for many (100+) projections, including Transverse Mercator and Lambert Conformal Conic. Included is a command line program for reprojecting points. It was originally written by Gerald Evenden of the USGS, and is in active use in various commercial and freeware software.
OGDI (the Open Geographic Datastore Interface) is an API that uses a standardized access method to work in conjunction with GIS software packages and various geospatial data products. It uses a client/server architecture to facilitate the dissemination of geospatial data products over any TCP/IP network, and a driver-oriented approach to facilitate access to several geospatial data products/formats.
Shapefile C Library is a C library for reading and writing ESRI Shapefiles and their related DBF files. All geometry types are supported, with robust DBF support. Shapelib is widely used for commercial and free projects. Shapelib includes command line utilities for dumping, subsetting, clipping, shifting, scaling, and reprojecting shapefiles.
The OGR Simple Features Library is a C++ library providing read/write support for a variety of Geospatial (GIS) vector file formats including Shapefiles, Mapinfo MID/MIF and TAB, PostGIS, and Oracle Spatial. It attempts to follow an OpenGIS Simple Features geometry model, and use OpenGIS coordinate system standards. C and Python bindings are provided. It is a component of the GDAL project.