A Surface is a model of a physical surface like the original ground at a site, a borrow pit or a road. It starts with TOPO points who's elevations are on the physical surface. From these, TPC generates a TIN (Triangulated Irregular Network) which is a series of contiguous triangles that represent (model) the physical surface. These triangles are sometimes called '3D Faces' or 'Polygon Meshes'.

A survey can include any number of surfaces just like it can have any number of traverses or drawings. Surfaces can be added, deleted, duplicated, edited and displayed in drawings using Surface Settings. Having multiple surfaces opens the door to work with existing vs proposed surfaces, volumes between surfaces, cut/fill reports between surfaces and much more. Here are some examples of how you might use multiple surfaces. See Multiple Surfaces.

Example: If you are surveying stockpiles of crushed rock, you can have a surface for the 1" minus pile and another surface for the 3" minus pile. Each surface can compute the volume of rock in the pile.
Example: You can survey an excavation site each month to determine the quantities removed.

Surfaces are Dynamic

Surfaces are generated from survey points. If the coordinates or elevation of a survey point in the surface change, the surface changes. It's pretty simple. So go ahead and create the surface. Later on when you update the survey points to the correct benchmark elevation the whole surface recomputes - dynamically.

You can also select a traverse as the source of a surface. Start your surface with the points you have then go back and 'fill in' the areas that need more detail simply by adding those points to the source traverse. The next time the surface is recomputed the new points are added into the surface - dynamically.

This whole idea of dynamic surfaces will change the way you think about working with surfaces in your surveys - for the better. See Editing Surfaces and Creating Surfaces.

Managing Surfaces

You manage surfaces in the Surface Manager dialog. You can create new surfaces, duplicate or edit existing surfaces and remove surfaces from the survey.

Including Surfaces in Drawings

To include a Surface in a drawing just tag it in the Surface Manager dialog. TPC will include the surface in the current drawing using the default surface settings. You might draw the major and minor contour lines for the surface or shade in the slopes.

You can include more than one surfaces in a drawing. You might use multiple surfaces to show different phases of an excavation or different stockpiles in a rock quarry. See Multiple Surfaces.

Editing (Modifying) Surfaces

You edit or modify the TIN by adding or removing points, adding breaklines and defining an optional border. All of these actions change the shape of the Surface.  Some times the topo points alone are adequate to accurately represent the physical surface. Some times adding a few breaklines is all you need. You'll find that there is some skill involved in collecting the best points in the field to accurately model the surface back in the office. See Editing Surfaces.

Restrict Elevations

You can limit the topo points that are included in a surface by elevation. If you have some 'whacky' elevation points in your survey, this is a great way to exclude them from the surface. See Surface dialog.

Surface Settings

Each surface has user settings that determine how the surface is represented in a drawing. These Surface Settings allow you to include major and minor contour lines with the colors, line types, labels and contour intervals you want. Other Surface Settings allow you to draw the TIN lines and breaklines, use shading to delineate the cut and fill areas or color in all the areas with a slope greater than 30 percent.

Each surface has its own settings (the default settings) which allows the surface to be displayed the same way in any number of drawings. But when you need it, a surface can be displayed in a drawing using unique Surface Settings. The unique surface settings are used instead of the surfaces default settings, allowing you to change contour intervals, colors, line types or whatever.

Surface Information

TPC collects information about the contours it creates to help you correct problems or improve the shape of the surface. You'll find information about the surface in the Surface dialog, Volume dialog and Slope Analysis dialog.

Generating Transects

TPC can generate transects from a surface. You just draw a line across a surface where you want the transect to be, then use the Create Transect from Surface command and TPC will create a traverse with a point for each intersection of the TIN and the line, arc or spiral. See Creating Transects From Surfaces.

Generating Cut Sheets

TPC can generate a cut sheet that shows the cut or fill from the surface to each point in a traverse. You might create a traverse for a building pad, translate it to its design grade, and then generate the cut sheet. Now you will know how much to excavate at each building corner to get to grade. See Creating Cut Sheets from Surfaces. (Professional Edition only)


TPC generates surface volumes in the Volume tab of the surface settings. You can generate volumes to the surface border (default), to an elevation, or to another surface. (Professional Edition only)

Slope Analysis

The Professional edition of TPC Desktop includes tools to analyze surface slopes. TPC can determine the parts of the surface that lie within any arbitrary slope range you specify, such as 0% to 10%, or 11% to 20%. These areas can also be shaded to indicate their slope range. See Slope Analysis.

Adding a Contour Line to a Legend

Right click a contour line and choose Append to Legend. TPC generates a legend item with the contour line type, the contour elevation and the name of the surface.


Premium, Professional