MICROSTATION COORDINATE SPACE

FREE

Description

When starting any project, 2D or 3D it is critical that the information falls within a certain area of the DGN file. The “Solids Working Area” (SWA) is approximately 4.29km around 0,0.

This may not seem like a problem, but if the project is drawn to Real World Coordinates, it will, more than likely, fall outside of the SWA. This can cause errors when copying information, it may be noticeable to a very small degree that measurement is inaccurate, but Dynamic Views may be inconsistent in 3D files. When the process below is followed, the files will be located optimally for both internal operations and data exchange with the full design team.

Locating the survey

At the start of a project, the seed file needs to be defined correctly to ensure all data is located coincidentally to real-world coordinates, but within 4.29km of the file’s centre. This is achieved by redefining the Global Origin. It is critical that this is carried out in the seed file so all new files use the same coordinate system. If files already exist on the project, these must be corrected to match.

Identify and reference the correct survey or map. Confirm also that there is a valid license to use the map. You could be infringing copyright if you use an unlicensed map.
It is most likely that this map is drawn to real world coordinates and is outside of the SWA.
Check this by displaying the SWA using the keyin cmd_showSolidsWorkingArea.
Note: this command has been removed in later versions of MicroStation. In OpenBuildings Designer use the View > Solids Working Area > Toggle SWA Display tool.

Move the lower left corner of the survey or map to the 0,0 point:

In the Reference dialog box, select the reference and pick Move Reference.

Select the lower left corner of the survey or map.

In the Keyin window, type in “XY=0,0”. The reference will be relocated at the file’s centre point. You can confirm this as it should align with the ACS Triad.

Setting the coordinate system

Identify a known location for your project. This may be a grid intersection, a site setting out point, a survey station, or a physical object such as the corner or a building.

Ascertain the OS coordinates for this point, or the local grid if the project is not in the UK. With an attached OS Map, the coordinates should be shown on the grid.

You need to reassign the 0,0 point in your seed file to these coordinates.

Keyin “GO=” (or “active origin”) to reposition the file’s Global Origin.
The Global Origin is exactly in the centre of the Solids Working Area. By default this is labelled 0,0. All that is being done is changing the label (the X and Y coordinates) of that point.

In the Tool Settings window, make sure Mode is set to Monument Point.
Enter the X, Y and Z co-ordinates of your setting out point. Always remember to double-check the units of the file and enter the coordinates with the correct number of 0s

Your status bar prompt will now read:
Global Origin > Identify the monument at x,y,z in the design

Snap onto the setting out point identified in step 1 and click to accept.
The Global Origin will be repositioned to suit this setting out point.

File > Save Settings (Ctrl+F)

Your project will now be accurate and also set out to the correct site coordinates.

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