BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, and image and signal-processing tools.
LibRaw is a library for reading RAW files obtained from digital photo cameras (CRW/CR2, NEF, RAF, DNG, and others). LibRaw is based on the source codes of the dcraw utility, though some of the drawbacks of dcraw have been eliminated. The users of the library are provided with an API to be used when writing their software programs.
PLIB is a set of libraries to write games and other realtime interactive applications that are 100% portable across a wide range of hardware and operating systems. It's used by Majik3D, FlightGear, and others, and includes libraries for GUI widgets, sound replay, geometry, scene graph, joystick, and fonts/text.
UniConvertor is a universal vector graphics translator. It uses the sK1 engine to convert one format to another. There are import filters for CorelDraw (CDR and CMX), Adobe Illustrator (AI), Scalable Vector Graphics (SVG), and some other formats, and export filters for AI, SVG, WMF, and sK1's own format.
HPGS is an HPGL/2 interpreter, which renders HPGL/2 and processes vector data through a Postscript-like API. It can render to EPS and PNG files. For rendering the scenery to pixel formats, it includes a rendering engine which draws vector graphics into pixel buffers. It also interprets inline PCL images.