Bisplining is set to work in a specified direction defined by a rotation angle with default value 0 (NS).
- for a bearing of 90, it will spline (NS) for lines which have a bearing within 70-110 degs (+-20 from 90)
- for a bearing of 0 it will spline EW for lines bearing 340-020.
- for a bearing of 45 you will have to select "rotate dataset". Otherwise, the splining algorithm will not able to cross many nodes and the output grid will be mostly blank.