Simple GIS Cogo Example

Simple GIS contains many rich editing tools to create and edit your data.  One of these tools is the Cogo editing feature which allows you to enter new feature using survey measurements.  This tutorial will introduce this tool and its functionality.

To begin, make sure you have toggled editing on for the current layer in your map and then select "Add Cogo Features" from the "Layer Edit" pull down menu.  If the layer you are editing is a graphic layer, you will prompted to select the geometry type you are editing since a graphic layer can contain multiple geometry types (point, line, polygon). Otherwise, if you are editing a shapefile, the geometry type will be picked from the shapefile since a shapefile only contains a single type of geometry. Also, when you first select this feature, you will see a pop up dialog box reminding you that you must first select a starting point from your map to begin entering features by Cogo measurements. The the dialog box below will appear. To enter your starting point, you can either manually type an X-Coordinate and Y-Coordinate in the appropriate box or click the

Angle/Distance: Angles can be entered as decimal degrees (DDD.dddd) and distance entered the same as for Bearings/Distance. You would add, insert, or replace an existing measurement using the same buttons as described above for the Bearings/Distance cogo measurement.

Curve: Use this tab to define curves defined by a radius and length or chord length. To begin, you should select the direction of the curve. In other words, is curve curving to the left or right from the starting point of the curve. Next, enter the radius and distance or length of the curve. Just like on the Bearings/Distance tab, the units for the radius and distance inherits from the MapDataView documents Measure Units settings. Also, if the value entered for Distance is a chord length, you should make sure the “Chord?” check box is checked. You would then either add, insert, or replace the curve description to the cogo parts list using the same buttons as described above for the Bearings/Distance entry.

button. If you wish to replace a cogo measurement, select the part from the “Cogo Parts” list box and click the

Simple GIS supports entering Cogo measurements by Bearing & Distance, Decimal Degrees & Distance, Curves using Radius & Length, or manual coordinate entry. Simply click on the appropriate tab to enter measurements in the desired form. Each entry method is described in more detail below:

tool and then clicking on a point in your map.

Cogo Editing in Simple GIS

XY: Select this tab to manually enter X and Y coordinates. Alternatively, rather than manually typing the X coordinate and Y coordinate, you can select a point from the map by clicking the

If you wish to insert a cogo measurement in front of the currently selected part in the “Cogo Parts” list box, click the

Simple GIS - Cogo Tool Example
Cogo by Decimal Degrees & Distance in Simple GIS

As you add each cogo measurement you would see that segment drawn in your map document. When you have completed entering all measurements, click the “Complete” button to dismiss the Cogo dialog box and commit the new features to your layer.

Bearings/Distance: Bearings are entered in the form of “D dd mm ss D” where “D” = direction (N = North, S = South, E = East, W = West), “dd” = degrees, “mm” = minutes, and “ss” = seconds. Distance is entered in the units as designated by the suffix at the end of the “Distance” input box (ft = feet, m = meters). The units for the Cogo tool are inherited from the Measure Units specified for the MapDataView document. Therefore, if the measure units for the MapDataView document are in feet, then the units for the Cogo tool will be in feet as well. Once entered, click the "+" button to add the cogo measurement to the “Cogo Parts” list box on the left hand side of the Cogo dialog box. Also, as you add cogo measurements to this list box, the segments will be drawn in your MapDataView document if they are located in the current extent of your MapDataView document. 

Cogo by Bearing & Distance in Simple GIS
Entering Curves in Simple GIS Cogo Tool

We could start at any point as long as we proceed in the same direction adding each segment as we go from one end to the next. In our example above, if we started at the upper right corner and worked our way around in a counter clockwise direction, our Cogo Parts list in the Cogo dialog box would look like that shown below:

Now consider we had a plat with the Cogo measurements as shown below:

button and then click a point on the map to use as your starting position.