What is in front of the buildings that are not short?
The trees are in front of the towers.
    src    edge_attr  dst
0     0  in front of    2
1     0         near    5
2     0       behind    5
3     0  in front of    1
4     1       behind    5
5     1         near    2
6     1       behind    0
7     2         near    1
8     2       behind    0
9     3         near    5
10    4        above    5
11    4        above    6
12    5         near    3
13    5  in front of    1
14    5         near    0
15    5        below    6
16    5  in front of    0
17    6           in    5