Towers and arrows

Normal sudoku rules apply. Place the digits 1-9 once each in every row, column and 3x3 box. Digits on an arrowed line sum to the total given in the connected circle, digits may repeat if other rules allow. Each digit in the grid represents the height of a building in its cell. Taller buildings obstruct the view of shorter ones behind them. Clues outside the grid give the number of buildings visible from that vantage point in the clue's row or column.