Points, Surfaces, and Grading
Points and Description Keys
Points can be created manually, by importing field book or ASCII files, or by conversion from AutoCAD entities. Description keys match the raw description on import and apply a point style, label style, layer, and format conversion. The trap: description keys apply only at creation time, so changing a key later does not retroactively restyle existing points unless the points are re-imported or the description is re-applied. Point groups, by contrast, are dynamic - a point group with a description or elevation filter updates automatically as points change.
Surfaces
A TIN surface is built from breaklines, points, and boundaries. Breaklines come in three flavors: standard (adds triangle edges without altering elevations), proximity (adds edges within a distance), and wall (creates vertical faces for near-vertical features like retaining walls). Boundaries include outer (clips the surface), show, hide, and data clip. A frequent exam trap is confusing a hide boundary with a data clip boundary: hide boundaries suppress display and triangulation but leave the data, while data clip boundaries exclude data from the build entirely.
Grading
Grading objects project from a feature line at a specified slope to a target - a distance, elevation, or relative elevation. Grading groups hold the criteria and generate the daylight lines that feed corridor-less site design.
Worked Example
You import 400 points with description code "TC" and want them on a separate layer with a tree symbol. The correct sequence is: define a description key for "TC" mapping to the point style, label style, and layer, then import. If the points already exist, editing the key does nothing - you must re-apply the description or re-import.