About creating a line with the 2-Point Line window
This topic applies to ArcEditor and ArcInfo only.
A common editing task you encounter when creating lines from COGO measurements is to add COGO lines between existing features you have already created with a traverse. In the example below, the parcel boundaries along the road and across the back of the parcels have been created. Now you need to add the lines between the parcels. While you could use the Traverse window to accomplish this, the 2-Point Line window allows you to enter these boundaries more quickly. Lines with COGO attributes are automatically created as two-point COGO lines.
The 2-Point Line window lets you create line features using a wide variety of construction methods. You can add straight lines or curved features using Direction–Distance, Angle–Distance, Curve, and Tangent Curve methods.
Populating COGO attributes
If the output layer has COGO fields, the COGO values you type into the 2-Point Line window are written to the appropriate attributes.
Setting the reference
You can set the start point of the new feature by entering the x and y coordinates, clicking on the map, or using the coordinates of the start or end point of a selected line feature.
If you want to create a segment using the Angle–Distance or Tangent Curve constructions, you need to set a reference direction to which the segment will be relative. You can either enter a direction or use the direction of the selected line feature. If you want to click the map to set the reference direction, use the Direction and distance of a line option of the COGO Report window and copy and paste the direction into the Direction edit box.
The reference direction is a foresight, the direction toward the start point. If you are using a selected line, the reference direction is toward the end of the line you choose.
Snapping to existing features
When you are adding line features, you can choose to snap the endpoint to existing features. This allows you to take small differences between the ground direction and distance and features in your dataset into account. In the graphic below, a line feature is being added at a direction of N0E and a distance of 115 feet. When this feature is added, it will snap to the first snap point based on the current snapping environment. The geometry of the feature could be slightly different from the Direction and Distance attributes that are written.
This option uses the general snapping environment to locate a snap point within the snap tolerance of the end of the constructed line feature. When editing, you have a choice of snapping environments: the Snapping toolbar and classic snapping, which resembles the ArcGIS 9.3 snapping environment. The Snapping toolbar uses a snapping tolerance in pixels, while classic snapping allows you to set a tolerance in pixels or map units. To ensure you snap the end of your line to features within a reasonable distance, you could consider using classic snapping and specifying the snap tolerance in map units instead of pixels.
You enter a start point, direction, and a distance. The direction is based on the current Direction Type and Direction Units for the editing environment. The distance can be in any of the supported distance units.
You enter a start point, reference direction, angle, and a distance. The reference direction is based on the current Direction Type and Direction Units for the editing environment. The angle is based on the current Direction Units. The distance can be in any of the supported distance units.
The angle—also called the backsight angle—is a clockwise angle between the inverse of the reference direction and the intended line. For example, if you specify a reference direction of S45°E and an angle of 135°, the following occurs:
Inverse the reference direction: S45°E + 180° = N45°W
Add 135°: N45°W + 135° = N90°E
To add a line tangent to the reference direction, you need to use an angle of 180°.
You enter a start point, two curve parameters, a curve direction, and whether the curve is to the left or right. A new feature is created in the target layer. A curve can be created by entering two of the following parameters:
- Chord—Also referred to as the chord distance, the straight line distance between the endpoints of the curve.
- Angle—The angle formed between the end points of the curve and the center point.
- Arc—Length along the curve. The arc length needs to be greater than the chord distance.
- Radius—Length from the center point to the curve.
You cannot add the tangent distance (the distance between the endpoints of the curve and their intersection point) as a parameter for the curve. If you have a tangent distance, use the Curve Calculator dialog box to determine one of the other curve parameters.
The curve direction can be one of three types:
- Chord direction—Direction from the start point of the curve to the end point of the curve.
- Tangent direction—Direction to the tangent point of the curve. This creates a curve where the center point of the curve is at 90 degrees from the tangent direction, on the same side as the turn direction.
- Radial direction—Direction toward the center point of the curve.
The curve direction is based on the current Direction Type and Direction Units for the editing environment. The angle is based on the current Direction Units. The distances can be in any of the supported distance units.
Tangent Curve construction
You enter a start point, reference direction, two curve parameters, and whether the curve is to the left or right. A new feature is created in the target layer. The curve is created from the start point with the center point of the curve 90 degrees from the reference direction, on the same side as the turn direction.