Using something other than light, sound, and radiation?

ping pong balls, airflow, anything that mimics a ray. but all those are obviously inferior to what you mentioned.
thermal scan its a use of radiation
touching

fill it full of plaster and remove it and see what it looks like when its not in the "dark area".



needless to say i have no idea what type of dark area you are talking about.

Airflow/touching are both uses of matter to visualize "dark areas." I was looking for more of a type of long range visualization like light and sound.



Any type of dark area really, from something as vast as planets without light or even something as small as a room without electricity.

I am trying to think of new ways to quickly map out surroundings.

Something other than light/sonar/radar/etc.

aside from developing some skill that lets you know stuff just by thinking about it i don't think there is much else.

True