1. The document discusses how to get an overview of an unknown research field using open data and visualization tools. It describes exploring a research domain on the Open Knowledge Maps website by visualizing a search on the PLOS database.
2. Key challenges in developing knowledge domain visualizations are identified as the availability of open bibliographic and bibliometric data, usability and ensuring the tools are useful for researchers' daily work, and addressing systematic biases and algorithmic errors in automated systems.
3. The vision presented is developing collaborative visualizations of all science domains based on open data, with input from domain experts and programmers, similar to how Wikipedia functions, to evaluate and improve the visualizations.