Attaching or Inserting Drawing Files with Geographic Data

When you attach or insert a drawing file in another drawing, and both files contain geographic location information, the program can automatically position the referenced or inserted drawing with the help of the geographic location information.

The program uses the geographic marker as a base point and inserts the drawing at the appropriate place. If the GIS coordinate systems of both drawings are the same, all other points in the referenced/inserted drawing transform correctly and continue to map to the correct geographic locations.

If the GIS coordinate systems are not the same, only the geographic marker transforms correctly to the host drawing’s GIS coordinate system. The other points may not transform correctly and may indicate incorrect geographic locations. Hence, the system warns you if it detects a coordinate system mismatch when you attach or insert the drawing. It however does not prevent you from attaching or inserting it.

Additional concerns for Xref drawings

When a drawing file is attached to another, one file can change independently of the other.

Some changes can have an adverse effect on drawing files containing geographic location data. For example:

• Moving the geographic location
  The GIS coordinate system of a drawing is hinged on to the geographic marker. As such, if you move the geographic marker of the host drawing or the referenced drawing, the points on the referenced drawing may lose context. As such they may not transform correctly and may not indicate the correct geographic locations.
  In such a case we suggest that you detach the referenced drawing and attach it again.
• Changing the GIS coordinate system
  Changing the coordinate system in a drawing file results in a coordinate system mismatch between the host drawing file and referenced drawing file. Unlike at attach time, the system does not warn you of a coordinate system mismatch. Consequently, the points in the referenced drawing file do not transform to the coordinate system of the host drawing. Hence, the points on the referenced file may not indicate the correct geographic location.
  In such a case we suggest that you:
  

  1. Change the GIS coordinate systems of the drawings such that the host drawing file and the referenced drawing file have the same GIS coordinate system.
  2. Detach the referenced drawing file and attach it again.