Help:Surveyor Topology Section Extend
From TrainzOnline
Add ground (X)
Select the Add Ground (X) tool. Click LMB in the void just off the edge of the baseboard to add another baseboard in that direction.
By default ground sections use a 10m grid, where each adjustable terrain 'point' is 10m apart. If your route requires finer detail you can create sections which use a 5m grid. These ground sections will use four times more memory than the standard 10m grid and should be reserved for when fine detail is absolutely required.
To create a section with a 5m grid, click on the drop down list to the right of the Add Ground button, and select the 5m option. Now add the terrain as normal. You can also update existing sections by clicking on them whilst the 5m grid option is selected.
