Fall Conference
September 2012
GIS in MicroStation SELECT series 3
Inga Morozoff, Bentley Systems, Incorporated
GIS in MicroStation V8i SELECT series 3
Assign a Geographic Coordinate System
Geo-coordination features let you specify the position of design contents on the earth’s surface. Once that position is established, a design can be coordinated with other data for which the geographic location is known.
A geographic coordinate system can be applied to structural-scale data as well as earth-scale data. Earth-scale data is used when designing larger scale infrastructure, mapping, and surveying while structural-scale data is used when designing buildings, stadiums, industrial plants, and other structures.
For additional information, please refer to the following wiki article: http://communities.bentley.com/Wiki/view.aspx/Assigning_A_Geographic_Coordinate_System
Exercise – Attach a Geographic Coordinate System
1. Start MicroStation.
2. Set the workspace to Untitled/Untitled/Default
3. Open c:/Airport Design/Airport.dgn
4. Select Tools > Geographic > Open as Toolbox
5. This tool box will be used throughout this workshop.
6. Choose Select Geographic Coordinate System. Note the design file does not have a geographic coordinate system (GCS) assigned.
7. From the icon bar, choose From Library.
8. Expand the Library node and explore the contents.
When looking for a geographic coordinate system (GCS) to apply to design data in MicroStation, you can select a GCS from an extensive library of predefined geographic coordinate systems.
You can select from those, or you can use the search engine to search for a specific one you may be interested in. You can also create your own coordinate systems using Bentley Map and import those into MicroStation
9. Locate and select NC83F – North Carolina State Plane, US Foot
10. Click OK. In most instances there is no need to change the storage units of the model.
Reprojecting MicroStation Reference
Once you’ve selected a master coordinate system, references can be attached and georeferenced. To orient references to the correct position with respect to the master coordinate system, it’s just a matter of selecting it and setting the georeference option to reproject. In doing so, MicroStation V8i will reproject the selected file relative to the coordinate system of the active model. You should also note that the references retain their original coordinate system so you don’t need to change how everyone else is working.
Exercise – Review Reference
1. Open …/Parcels.dgn
2. Choose Select Geographic Coordinate System and review the assigned GCS. Note that it differs from the airport design.
Exercise – Attach Reference
3. Open …/Airport Design.dgn
4. From the References dialog, choose Attach
5. Select …/Parcels.dgn with the Attachment Mode set to Coincident World.
6. Fit the view and note that the parcels fall 425 miles west and 143 miles south of the airport.
Exercise – Reproject Reference
7. In the References dialog, turn on the display of the GeoCS, Orientation and Priority columns. Note that the GeoCS column displays the reference GCS in red. This indicates that there is a mismatch between the GCS of the reference and that of the active model to which it’s attached.
8. Change the orientation to Geographic Reprojected by clicking in the column. Note that the GeoCS column is now displayed in black.
9. Change the Priority to -5 so that the content of the reference lays behind the airport design elements. This is being done for aesthetic reasons only.
10. Fit the view. The parcels have been reprojected to fit the GCS of the active model. This reprojection is done in memory only – the content of the parcel file is not being modified or altered in any way.
Reproject Raster Images
Geocoordination is not restricted to vector files; it also works on rasters, in this case imagery.
For a raster to be reprojected, a geographic coordinate system must be available, and one of the two following situations must be true:
· Inherit GeoCS from Model is turned OFF in the Raster Manager or set to Not Inherited during attachment.
· The raster is attached to a reprojected reference.
Exercise – Attach Images
1. Continuing in Airport.dgn, choose Attach > Raster from the Raster Manager dialog.
2. Navigate to the Images folder and select the ten images.
3. In the Raster Attachment Options dialog, ensure that Inherit GeoCS from Model is set to Inherited.
4. Click Attach
5. Note mismatch between the vector graphics and the imagery. This is especially obvious at the south end of the runway.
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Exercise – Reproject Images
6. Continuing in Airport.dgn, turn on the Coordinate System and Inherit GeoCS from Model columns in the Raster Manager dialog. Note the entries in the Coordinate System column are displayed in red. This indicates a mismatch between the active model GCS and the GCS of the images.
7. Select all images, and turn off Inherit GeoCS from Model. The images are now reprojected.
8. Fit view.
Reproject Design Data
MicroStation can reproject design data from one geographic coordinate system to another. When a new GCS is selected and the reproject option is chosen in the confirmation dialog, the data within the model to which you are assigning the GCS is permanently reprojected. When a reference attached with the geographic reprojection option is loaded, the data within the referenced model is reprojected temporarily and not written back to the file.
Exercise – Reproject Design Data
1. Continuing in Airport.dgn, choose Edit Reprojection Settings from the Geographic Coordinate System dialog and review the contents. (No changes are required.)
2. Choose Select Geographic Coordinate System from the Geographic tool box.
3. From the Geographic Coordinate System dialog, choose From Library
4. On the Search tab, enter LL83. Click Find Now.
5. In the Geographic Coordinate System Changed dialog, ensure that Reproject the data to the new Geographic Coordinate System is selected. Press OK.
6. Fit the view. The design data, reference and attached images are reprojected.
7. Before continuing, detach the images.
Running Coordinate Display
Right-clicking in the Running Coordinates section of the status bar turns on the coordinates display. As you move your cursor, the coordinates of your current position display according to the active Tentative Point Mode. To get a longitude, latitude coordinate readout, select ACS Position from the left click menu.
Exercise – Enable Running Coordinates
1. Open Flood Study.dgn
2. Verify that the GCS is NC83F
3. Verify that the GCS is the active Auxiliary Coordinate System.
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