Original Article Date: June 5, 2003
Confused about the Global Origin in MicroStation V7? This article should help clear things up. It even has pictures to help you visualize what's going on.
The Global Origin is the location xy=0,0 in a design file. This location can be located either inside or outside of the design plane. Below is a representation of the typical 2D design plane showing the global origin (0,0) in the center.
For most purposes the Global Origin is fine where it is, however when working with maps it is sometimes necessary to shift the origin in order to accommodate very large mapping coordinates.
Let's assume that your file has working units set up to 1m:100cm:10pu/cm or 1m:1000mm:1pu/mm (which is really the same thing), the "size" of your design plane could be graphically represented as shown below.
If you need more information about working units, refer to Understanding Working Units
To help you understand what's going on, the following tidbit that Barry Bentley wrote explains it very well!:
"When you place graphic elements in a file, you can think of drawing them on a huge piece of graph paper. When you move the global origin, you can picture yourself erasing the old x and y axes and drawing new ones in a different location on that graph paper. The graphics elements didn't move on the paper, but their coordinates did because the global origin (axes) moved. MicroStation reports the coordinates relative to the global origin, and accepts input coordinates taking the global origin into account."
Note: The following information deals with the GO command which is a setting that may not be able to be easily un-done. If you've made a mistake, you can exit the file without saving the settings and then go back and try again.
To determine the current location of the global origin
Just keyin GO=$
MicroStation will report the distances along each axis from the design plane origin to the point in the file with the coordinates of 0,0.
In this example, the readout at the bottom of the screen will be GO=2147483.6480,2147483.6480
To assign XY cooridnates to the design plane origin
Keyin GO=[x-value,y-value] followed by a reset.
For example, keyin in GO=500,1000 would result in the following...notice how the location XY=0,0 is actually off of the design plane now.
Using an element to set the global origin
To change the global origin to a known location in the file (such as an element) and assign it XY=0,0, just keyin GO=0,0 followed by a data point on the element.
Set the global origin to a known location and assign it XY coordinates:
Use the keyin GO=[x-value,y-value] and enter a datapoint on an existing element in the file.
To locate the global origin at the design plane origin and assign it XY=0,0
Keyin GO=0,0 and then press reset
To set the center of the design plane to XY=x-value,y-value
Keyin: GO=[x-value,y-value] followed by a [carriage_return]. Then keyin this: xy=0,0|uor
Thanks to Bentley’s Paul Johnson for pointing this out!
AskInga Article #146