When a VTP line crosses a Cell (LOD8 square) 2 lines are generated as explained in the MS SDKs. Say that a line has 9 points, 5 of which belong Cell X and the remaining 4 points belong to the adjacent Cell Y. SBuilder generates 1 line with 6 points (5 from X and 1 from Y) and another line with 5 points (1 from X and 4 from Y).
When you append this VTP file you will get this broken line. This is not an error. It is just the way MS implemented VTP scenery.
In order that you "get back what you compiled" I add a switch called "Join multi-Cell Lines" in the section "Append VTP BGL" of the Preferences. If you check this switch, SBuilder firstly appends VTP BGLs files as it allways does. Then it joins lines that have 2 terminal points on each side of a Cell border.
I also point out the "Line/Poly Joining" preferences. Here are some meanings:
a) "display based joining" - Say that you are to join line A (points 1 to N) with line B (points 1 to M). Say that the joining points are N from A and 1 from B. When you set "display based joining" the lines will actually be joined if the distance between the joining points is equal or smaller than 3 "display pixels". If you unset this switch the lines will be joined if the distance between the joining points is equal or smaller than a LOD21 edge (4,8 meters more or less).
This means that joining will depend on the ZOOM! If you can not join 2 lines at a certain ZOOM (because the joining points are 4 pixels apart) you will be able to join if you diminuish the ZOOM.
This applies for lines and polygons.
b) "ignore line direction" - when unset you can only join 2 lines if a START point of one of the lines is near the END point of the other line. In order to join the lines you would need to "Reverse" the points in the Lines properties.
When you set this swithch the direction will be ignored and it is possible to join at the 2 START points of 2 lines or at the 2 END points of 2 lines
c) "ignore line labels" - if set, you can not join lines with different names.
Hope this is useful. This build (dated December, 1, 2004) is now at:
http://www.ptsim.com/downloads/sbxxx.zip
Regards, Luis