OpenAPC is an APC (Advanced Process Control) solution that is highly flexible and configurable and covers a wide range of automation, visualization, and process control tasks from home control up to industrial automation. Control applications created with the OpenAPC editor's visual interface can perform several tasks dependent on how the application is configured and used. The application is available for many different platforms, so OpenAPC projects can be switched over to a different platform easily.
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.
timeplotters is a collection of command line tools for visualizing temporal data. It is especially useful for visualizing data from ad-hoc program logs, helping you to spot patterns and anomalies that you would not otherwise see by just watching how the program works or by looking at the logs with the naked eye. Its input format is tailored to event types typically seen in program logs, and the visualization methods are tailored to the questions typically asked about program performance (e.g. distribution of activity durations).
OpenVRML is a VRML and X3D browser plug-in and C++ toolkit for incorporating VRML/X3D support into applications. It provides VRML97 and Classic VRML X3D parsers, a runtime, and an OpenGL renderer as C++ libraries. The renderer is fully separate from the runtime library so that users can also provide their own renderer. The OpenVRML browser is provided as a D-Bus service, and is embeddable in host applications using XEmbed. The distribution provides both a stand-alone host and a host that runs as a Mozilla plug-in.
Spaghetti Parenthesis Visualizer is an in-browser (meaning that it doesn't send your code to a server) tool that takes deeply nested conditionals in languages that follow in C's footsteps, including Python, Perl, PHP, and Java, SQL queries, or some Lisp code, and provides two visual presentations that clearly and cleanly display how deep each part of the code is in the layers of nesting.
JGraph is a free, mature, and robust Java diagramming library. It contains all the graph visualization, layout, and interaction functionality you might expect in a graph library, including multiple views, layering, zoom, drag and drop, undo, automatic expanding and collapsing, routing, and layouts. You can create workflow editors, BPMN, CAD tools, network diagrams, database visualization tools, and more. It is fully documented, including examples, and has an active support community.