Understanding CogoPoints

AutoCAD Land Desktop ActiveX & VBA

Understanding CogoPoints


For each Land Desktop Project, there is a COGO points database. The ActiveX Object Model gives access to this database through the CogoPoints collection. Through this collection, you can add, delete, and modify a CogoPoint.

A CogoPoint has Northing, Easting, and Elevation fields. If the GroupName is set for the CogoPoint, then you will also see the overrides from that PointGroup.

PointGroups and DescriptionKey are also exposed through the ActiveX Object Model. These collections and objects allow you to work with groups of COGO points.

CogoPoint and AeccPoint

In a Land Development document, a COGO point can exist in the drawing. This point can be represented as either an Arx object or a Softdesk block. If the point is an Arx object, then you can access it by using the COM wrapper AeccPoint. This point does not necessarily exist in the point database. If it does exist in the database, then you could access it by using a CogoPoint object.

To state it differently, a CogoPoint object is a point database object and an AeccPoint is a COM wrapper for the Arx object.

A CogoPoint and AeccPoint can represent the same geometry. If you change the coordinates for a CogoPoint, the Arx object in the drawing will be updated.

Point Number verses Item Number

When the collection class is built for CogoPoints, several things happen. First, a list of the currently used points is generated. These points are then added to the collection. For example, the point database has points with point numbers 1, 3, 5, and 7. When the collection is built, then the collection will have 4 items. Item(0) will be point 1, Item(1) point 3, Item(2) point 5, and Item(3) point 7. There is no correspondence between the Item number and the point number.

If you want to work with points by point number, use CogoPoints.PointByNumber.