This is a technique as well as an exercise (ie. it can be used in performance but it’s also an exercise in its own right).
Scene painting means building up the details of a room by ‘painting’ it using words and movements.
A student starts by coming into the space and detailing a single item in a room.
There is an overstuffed leather armchair in the far corner - it is worn out on the arms and where a person’s legs would naturally rest.
They describe it in as much detail as they want and can delineate its dimensions physically as well using their hands and body.
The next improviser adds another object to the room. Something that belongs with the first object.
You keep doing this until the room is sketched out in some detail.
Use the rule “If this is true, what else is true?” to help you know what to add in next. The room should appear cohesive.
As above, this is a performance technique and can be used ‘as is’ in shows.
Think about what kind of person would live in a room like the one you are creating.
If someone paints in a chair, have someone else in the group place a real chair in that location.
Put bulky items like beds out of the playing area (like in the audience).
Hang pictures and create most details on the 4th wall so you can keep looking at the audience.
Paint with all the senses - sight, sound, smell, touch taste.
It’s a lovely feeling when you use and expand on someone else’s idea:
Between the cushions of the leather armchair is a squashed packet of Cardinals.
You can paint characters in the room - this is a big enough variation as to have its own entry - Character painting