Offset slope not computing vertical nodes

When using the Offset slope command with the sampling distance set to 0.0, the resulting line only contains vertical nodes where the source line (offset reference line) contains horizontal nodes. As if vertical nodes are not computed at all. This seems very strange, especially considering the resulting line is created with vertical nodes and not elevated chorded horizontal nodes.
It doesn’t seem right for it not to work for offsetting line containing vertical nodes or an arc using a referenced slope. Am I doing something wrong?

You are correct - surprised that noone has seen that before!

The reason it has been missed is that the main use cases of this is to offset 3D strings that are provided from Engineering software products like InRoads, 12D or Civil 3D and none of those have the ability to have VPIs only on a linestring like TBC does, so we likely never tested it with TBC linestrings that had VPI nodes only. I will get this fixed before our upcoming 5.80 update.

If you add the nodes as Horizontal Nodes with Elevation they get created correctly.

Thanks for raising the issue


I was trying to use it to offset XML imported alignments from Civil 3D, used variable offset as a workaround. It would be great if the variable slope command had the ability to use a reference line for slope too!

Thanks Alan

Agreed - one of these days we will write our own Variable Offset Line and I will take this into account for sure - thanks for the feedback and comments - I hope to have this one fixed this week.