Free Software Foundation!

Aalib 'Aalib' is a low level gfx library that works on any kind of terminal. It does not require graphics devices (in fact, no graphical output is possible), and is particularly useful for those with older hardware who do not want to worry about overloading their systems with graphical applications.

Aewan 'Aewan' lets users create and edit ASCII art. Users move the cursor around with the arrow keys, "paint" characters by pressing the corresponding key, and choose foreground and background colors, and bold and blink attributes, with dialog boxes. They can also select, move, copy, and paste rectangular areas of the canvas. Aewan supports "intelligent" horizontal and vertical flipping (e.g., it converts "\" to "/", etc) and can work with multiple layers, turn transparency and visibility on and off for each layer, and change the order of the layers. Thus, each layer can be edited independently to generate a composite drawing. Layers can also be used as frames for an animation, thereby creating ASCII animations.

Asymptote 'Asymptote' is a script-based vector graphics language for technical drawing, inspired by MetaPost but with an improved C++-like syntax. It provides for figures the same high-quality level of typesetting that LaTeX does for scientific text. It is a programming language, not just a graphics program, so it can use the best features of both scripts and GUIs. High-level graphics commands are implemented in the language itself, so they can be tailored to specific applications. Labels and equations are typeset with LaTeX for high-quality PostScript output.

Autotrace Autotrace is a program which converts bitmap images to vector images. It can import images in BMP, TGA, PNM, PPM, PGM, PBM and those supported by ImageMagick, and can output Postscript, svg, xfig, swf, pstoedit, emf, dxf, cgm, mif, p2e and sk

Biggles Biggles is a Python module for the creation of publication-quality 2D scientific plots. Its features include an elegant, high-level interface, a simple TeX interpreter, and postscript, png, gif, svg, and x11 output formats.

CGAL The goal of the CGAL Project is to provide easy access to efficient and reliable geometric algorithms in the form of a C++ library. CGAL is used in various areas needing geometric computation, such as: computer graphics, scientific visualization, computer aided design and modeling, geographic information systems, molecular biology, medical imaging, robotics and motion planning, mesh generation, numerical methods...
CGAL offers data structures and algorithms like triangulations (2D constrained triangulations and Delaunay triangulations in 2D and 3D), Voronoi diagrams (for 2D and 3D points, 2D additively weighted Voronoi diagrams, and segment Voronoi diagrams), Boolean operations on polygons and polyhedra, arrangements of curves and their applications (2D and 3D envelopes, Minkowski sums) mesh generation (2D Delaunay mesh generation and 3D surface mesh generation, skin surfaces), geometry processing (surface mesh simplification, subdivision and parameterization, as well as estimation of local differential properties, and approximation of ridges and umbilics), alpha shapes, convex hull algorithms (in 2D, 3D and dD), operations on polygons (straight skeleton and offset polygon), search structures (kd trees for nearest neighbor search, and range and segment trees), interpolation (natural neighbor interpolation and placement of streamlines), shape analysis, fitting, and distances (smallest enclosing sphere of points or spheres, smallest enclosing ellipsoid of points, principal component analysis), and kinetic data structures. All these data structures and algorithms operate on geometric objects like points and segments, and perform geometric tests on them. These objects and predicates are regrouped in CGAL Kernels.

Cairo Cairo is a vector graphics library with cross-device output support. It currently supports the X Window System and in-memory image buffers as output targets. It is designed to produce identical output on all output media while taking advantage of display hardware acceleration when available (eg. through the X Render Extension). It provides a stateful user-level API with capabilities similar to the PDF 1.4 imaging model and provides operations including stroking and filling Bezier cubic splines, transforming and compositing translucent images, and antialiased text rendering.

EPiX 'ePiX', a collection of batch programs, creates mathematically accurate fgures, plots, and animations containing LaTeX typography. The input syntac is easy to learn. The output -- vector image files or LaTeX picture-like environments -- is expressly designed for use with LaTeX.

FroZenLight FroZenLight connects simple line art and mathematics. The source of light can be positioned so that either symmetric reflection patterns or secret messages (Cryptography) are created. Dozens of example light patterns and some math exercises are provided.

Frontier Many of Frontier's strengths rely on the degree-of-freedom-graph-based decomposition and recombination method called the Frontier Vertex Algorithm (FA) for geometric constraint systems. This algorithms applies equally well to 3d, although the sketcher user interface currently available with Frontier is restricted to 2d.

GRX GRX is a 2D graphics library originally written for DJGPP. It supports DOS, Linux console (svgalib and framebuffer drivers), X11, and Win32 (using the Mingw compiler).

GSEGrafix GSEGrafix is a GNOME application which uses an anti-aliased GNOME canvas for creating scientific and engineering plots. The program is written in C and reads ASCII plot-parameter files and data files. The plot-parameter files contain keywords and corresponding arguments for specifying plot parameters (such as data file names, data file formats, plot type, plot style, axis type, axis labels, etc). GSEGrafix can make rectangular two-dimensional plots (with linear, semilog, or loglog axes), histograms, polar-axis plots, and three-dimensional plots (with linear axes). Three-dimensional plots include points, contour, color, and mesh plots. Data for three-dimensional plots can also be used to create two-dimensional plots using contour lines or color to represent values of a third variable.

Gestalter Gestalter is a free vector drawing program. Its central element, the Bezier curve, is used as a base part for almost every other object. Complex paths are possible, compound paths can be constructed, grouping of elements is enabled, and everything can be screened by a mask. Adding and deleting of nodes is implemented as well as transformations (translation, rotation, scaling, and skewing).

Giv giv, The G(reat tk NU) Image Viewer, is an image viewer based on the gtk_image_viewer widget. It was designed especially for scientific vision and computational geometry and has support for drawing vector graphics on top of an image.

Grace Grace is a WYSIWYG 2D plotting tool to plot numerical data under the X Windows System and Motif (recent versions of Lesstif should be fine too). It combines a GUI with a scripting language to do calculations or automated tasks. Grace is a descendant of ACE/gr, also known as Xmgr.

Height Map Generator Height Map Editor edits, generates, and manipulates terrain height maps. These can be used in terrain renderers, which are used in games, applications, and demos. The program itself is small (the entire distribution is smaller than 400 Kb) but it can work with maps up to 10000x10000. Features include 16 levels of zoom, the ability to sink, smooth, or rise the terrain, the ability to put your own objects (ie volcanos, rivers, mountains, craters, etc.) in/on/over existing terrain, multiple brush sizes, flood and tolerance based fills, and the ability to place a height over terrain and add to or excavate from terrain.

JPIV: Java Particle Image Velocimetry JPIV is a platform independent, graphical stand-alone application for Particle Image Velocimetry (PIV). PIV is an optical technique for measuring fluid flow velocities. JPIV can be used for multi-pass PIV evaluation, sum of correlation ensemble evaluation, single pixel ensemble evaluation, vector field filtering, calculation of vorticity and other derivatives, third velocity component reconstruction, image and vector field display, vector field statistics and batch processing.

KolourPaint 'KolourPaint' is an easy-to-use paint program for KDE. Features include undo/redo, more than a dozen tools, selections, transparent image editing and zoom support (with an optional grid and thumbnail).

Magic Garden Magic garden is an Artificial Plants Laboratory. User can create plants and modify them in real time. It can be used by a child or an adult who knows about fractals and l-systems. Check out the galleries, here and here.

MtPaint 'mtPaint' is a simple GTK+1/2 painting program designed for creating icons and pixel-based artwork. It can edit indexed palette or 24 bit RGB images and offers basic painting and palette manipulation tools. Its main file format is PNG, although it can also handle JPEG, GIF, TIFF, BMP, XPM, and XBM files. Features include the ability to protect certain colours on the canvas from being painted over, up to 100 undo levels, a multiple image clipboard, the ability to view images between 10% and 2000% of their original size, and Spanish and Czech translations.