Puzzle #72: Seethrough

I've seen this genre under a variety of other names: Doors, Walls, Open Office. I'm using this name as that is what I've always known it under. It was called Doorkijkje in Breinbrekers.
This puzzle was inspired by a particularly nice puzzle at the WPC. It appeared in the Evergreens round and was atypical for this genre (like all puzzles in that round). That puzzle contained only the number 1 as clues. This one has numbers 1-3, but the logic involved is very similar to that one. I think this is a more challenging puzzle to solve though.

Rules for Seethrough

Rules: Seethrough

Draw some walls inbetween the squares. The numbers in the squares indicate the total number of squares visible in horizontal and vertical direction from that square. There can be no isolated squares. This means that you should be able to reach all squares by moving horizontally and vertically.