Geometry data collection methods: Volume.

Hi all,

How would one collect geometry data in a scene (created with game objects) to calculate the volume of individual internal rooms?

I hope calculate the volume of the space the player is in and send the data to an external program using OSC. The volume data should change in real-time when the player transitions to another room of a smaller/larger size and/or different shape.

Currently, I can think of using multiple ray-casts or collecting transform data of each object. However, ray-casts only apply to camera's is that right?

Any help would be greatly appreciated.