# Cogo calculations

To calculate distances, azimuths, point positions and other coordinate geometry (cogo) functions by various methods, use the Cogo functions provided in Trimble Access.

Most Cogo functions are available from the Cogo menu. Some Cogo functions are also available from the tap and hold menu in the map, depending on what is selected in the map.

The following Cogo functions are available only from the map:

- Compute intersection

- Compute center point

- Compute centerline

You can store the results of Cogo functions in the job.

When a scan point measured using a Trimble SX10 or SX12 scanning total station is used in a Cogo calculation, a point is created in the job at the same position as the scan point.

Selecting points to use in the Cogo function

Select points to use in the Cogo function by selecting them on the map.

The Snap‑to toolbar provides a simple way to select locations on objects in the map by snapping onto a specific point, even if no point exists. For example, you can use the Snap‑to toolbar to accurately select the end point of a line or the center of an arc from linework in a map file, such as a BIM model or DXF file. If a point does not already exist at the selected location, Trimble Access calculates a point. See Snap‑to toolbar.

If you have started a survey, tap the Fastfix softkey to create a construction point that you can use in the Cogo calculation. See Construction points.

Coordinate systems for Cogo calculations

When storing points calculated from cogo functions, tap Options and use the Coordinate view field to specify if the calculated point is to be stored as Global, Local or Grid coordinate values. See Coordinate view settings.

For some calculations, you must define a projection, or select a Scale factor‑only coordinate system. If the points were measured using GNSS, the coordinates of the point can only be displayed as grid values if a projection and a datum transformation are defined.

In general, do not compute points and then change the coordinate system or perform a calibration. If you do, these points will be inconsistent with the new coordinate system. An exception to this is points computed using the Brng‑dist from a point method.

Calculating distances

To change whether distances are displayed and calculated with reference to the ellipsoid, or to grid or ground coordinates, tap Options and change the selection in the Distances field. See Distance display and calculation.

If you are connected to a laser rangefinder, you can use it to measure distances or offsets. See Laser rangefinders.