What it is
openFrameworks is the C++ toolkit of the professional installation world: a curated set of libraries for graphics, audio, video, computer vision, and hardware, glued into a coherent creative-coding framework. When a piece needs native performance, custom hardware, camera tracking, or all three at once, oF is the traditional answer, and a large share of the canonical interactive installations of the last fifteen years were built on it.
It assumes you can write C++, set up a toolchain, and debug memory. That is the tallest setup bar on the map, and it buys near-total freedom.
What it costs
Free, open source, macOS, Windows, Linux (plus mobile and embedded targets).
Best for
Installation artists and studios with engineering chops, computer-vision-driven work, and pieces that must run fast on specific hardware for months.
Skip it if
There is any way to say your idea in a higher-level tool. The map exists to keep people from writing C++ when a patch or a preset would have done.