Surface

A surface is composed of the following:

• Name and description - each surface must have a unique name that identifies the surface from all the other surfaces in a survey.
• Survey points - only survey points with their 'Topo' status turned on are included in a surface.
• An optional source traverse - only the survey points in the traverse are used in the surface.
• An optional border - the border constrains the surface.
• Breaklines - breaklines change the configuration of the triangles in the TIN. We generally think of a breakline as any place two separate areas (planes) within the surface form a line.
• TIN - surfaces are created by triangulating the topo points. These triangles are typically discarded once the contour lines are created but can be retaind for volume computations and slope analysis.
Elevation limits - you can limit a surface to a minimum and/or maximum elevation. This is a great way to eliminate elevation blunders but can also help with simple excavation projects.
• Surface settings - these are the user settings that determine how to draw the contour lines, shade the slopes, show the breaklines and what layers to put them on.

Topo Points

Surfaces only use survey points designated as Topo Points. You can designate Topo Points in a number of different ways. Once the surface is drawn, you can even turn off the topo designation for individual points to fix blunders in your surface. To learn more about editing topo points see Editing Topo Points.

TPC generates its surface from a TIN (Triangulated Irregular Network). It creates triangles that model the surface, connecting all the border and topo points then interpolating the elevations along the edges of each triangle. See Creating a TIN.

Breaklines allow you to model grade breaks like ‘top of slope’ and ‘toe of slope’ with a minimal number of points. You can accomplish the same final surface shape without breaklines, but it requires taking numerous points along each breakline. It takes a little practice to gain experience collecting and using breaklines, but the investment is well worth it. See Using Breaklines.

Every surface has a border which constrains the surface. If you think of the surface as a TIN, the border is all the outside edges of all the outside triangles. These are the triangle edges that have just one triangle to the inside and no triangles to the outside.

The border defines the limits of a surface. Only the topo points that lie within the border are used to generate the surface. In this way, the border also affects the shape or 'outline' of the surface.

By default, a surface is constrained to its 'convex border'. Think of this a stretching a rubber-band around all the topo points in the surface. If you don't specify a border for a surface, it defaults to this convex border. This makes creating a surface very simple. See Inserting Surfaces.

You can also select a traverse to defines the border of the surface either when you create the surface or anytime you edit the surface. See Surface Borders.

Layers

By default, TPC groups a surfaces drawing objects onto layers. Major contour lines and labels are placed on the TPCContourMajor layer and so on. If you want to change the layers that a surface is placed on, use the Advanced dialog. See Surface Layers.

Optimizing Surfaces

Surfaces can be optimized to improve drawing speed, reduce memory requirements or allow interactive editing. See Optimizing Surfaces.

Surface Information

TPC collects information about the surfaces it creates to help you correct problems or improve the shape of the surface.

• Right click any minor contour line and choose Surface Tools, Surface Info.

Surfaces

Premium, Professional