Bentley
Latitude / Longitude to XY co-ordinates in MX
Sample start data :– lat, long, elevation
13.04480008,78.02510013,912
13.04480008,78.02540013,914
13.04480008,78.02570013,910
13.04480008,78.03000013,912
13.04480008,78.03030013,911
This data is to be converted to “UTM WGS 1984 datum, Zone 44 North”
To convert the data, I am using standard CAD functionality – done using MX V8i. Note that all of the functions/tools used to convert the data are standard built-in CAD tools, not MX tools.
Steps taken
1. Create a new MX project. As usual, MX starts with the drawing ‘draw.dgn’ in the DGN model ‘MX’ [the screenshot below shows the CAD Model icon]. If you want, you can create a new DGN to work in.
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2. File > CAD menu. This is to display the CAD menu as that is what I need to use.
3. Tools > Geographic > Select Geographic Coordinate System
4. Select the GCS for the model – I have selected LL84 below.
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5. Select ‘OK’ to change the units in the model.
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To confirm this, you can use ‘Settings > Design File...’ to check the working units. You will see that the Working Units are now Degrees/Seconds rather than metres/centimetres.
6. Select ‘Tools > Tool Boxes...’ and open the ‘XYZ Text’ tools.
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We are going to use this tool to read the lat/long file into the DGN file. Set the line weight to 5 or so, so that the points are easy to see when they are imported.
7. Use ‘Import Coordinates’ – note that the order is not XYZ, but YXZ. This is important!! [Horizontal coordinate is the longitude, vertical is latitude] Use the view controls to ‘Fit View’ to see the points that have been imported. A small sample is shown below.
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8. Use the CAD ‘Model’ to create a new model in the DGN file – think of this as a new ‘universe’ where we will set a different GCS.
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As you can see, it is a 3D Design model, the name and description can be anything.
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9. Set the GCS for this model to be ‘UTM84-44N’ [Tools > Geographic > Select Geographic Coordinate System]. The UTM zone is selected under the ‘WGS84’ folder shown below. Once again, click OK to re-set the model working units, as they should be m/mm in this model.
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10. We are now going to reference in the original model (with the lat/long coordinates) into this model (which is XY)
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Note that i am picking up the current drawing ‘draw.dgn’ - I have left the ‘Attachment Method’ on Interactive to show that I can pick any of the DGN models in this file to reference in, and also the orientation required – ‘Geographic-Reprojected’ in this case.
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11. From the References dialog panel, right click on the file just referenced in, and select ‘Merge into Master’. (Note the prompt at the bottom left of the status bar ‘Select view for merge’ – click in view 1) Click ‘OK’ on the message panel. This will bring the points into the XY coordinate system.
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12. Use ‘Export Coordinates’ from the XYZ Text toolbar to export all the points to a text file.
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Sample end data :– X, Y, elevation
177324.661,1443982.037,912.000
177357.227,1443981.655,914.000
177389.794,1443981.273,910.000
177856.575,1443975.802,912.000
177889.141,1443975.421,911.000
The file ‘XY-Out.txt’ now contains the correct coordinates, and can be imported to MX in the standard way.
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