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<< Click to Display Table of Contents >> GPS Mapping Tools |
  
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<< Click to Display Table of Contents >> GPS Mapping Tools |
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WireCAD v9 ENT provides several ways for you to visualize your locations, panels, backbones and circuits with relation to their GPS coordinates:
1.GPS calibrate (georeference) your dwg drawing and use the tools to pick GPS coordinates from the drawing and display graphical representations of your Locations, Panels and Backbones.
2.You can also set up isometric drawings to show your riser interconnect.
Isometric View Showing Backbone Interconnect
3.Use the Project Map. The functions are the same but the map detail will be less than that of a specific drawing. For example the map may show your building(s) but your CAD drawings will show the detail inside the buildings.
Map Tool - showing Location, Panels and Backbones
4.The Map Tool is available as a visualization in the Backbones grid to show you your Backbones in map view.
Map Tool - within the Backbones Visualizer
5.The Map Tool is available as a visualization in the Circuits grid to show you the GPS path of a selected circuit.
Map Tool - within the Circuit Visualizer
The WireCAD Locations table within the project database contains fields for named locations within your plant. In addition, those named locations can be associated with GPS coordinates.
Once the project Locations table has associated GPS coordinates you can visualize your data:
1.From your GPS calibrated dwg drawing.
2.From the Project Map tool.
3.From the Backbones grid Visualizer.
4.From the Circuits grid Visualizer.
Related Topics
GPS Mapping Tools For Drawings
GPS Mapping Tools for Map Tool
Note: Although we are showing a real world location in these examples the data is completely fictitious. Any resemblance to any data living or dead is purely coincidental.
There are several factors that effect the accuracy of the GPS coordinate system alignment:
•The accuracy of the drawing.
•The accuracy of the control points.
•The accuracy of the GPS coordinate provided.
From the wikipedia page on decimal precision:
The radius of the semi-major axis of the Earth at the equator is 6,378,137.0 meters resulting in a circumference of 40,075,161.2 meters. The equator is divided into 360 degrees of longitude, so each degree at the equator represents 111,319.9 meters or approximately 111.32 km. As one moves away from the equator towards a pole, however, one degree of longitude is multiplied by the cosine of the latitude, decreasing the distance, approaching zero at the pole. The number of decimal places required for a particular precision at the equator is:
Degree precision versus length
decimal places |
decimal degrees |
DMS |
qualitative scale that can be identified |
N/S or E/W at equator |
E/W at 23N/S |
E/W at 45N/S |
E/W at 67N/S |
0 |
1.0 |
1° 00′ 0″ |
country or large region |
111.32 km |
102.47 km |
78.71 km |
43.496 km |
1 |
0.1 |
0° 06′ 0″ |
large city or district |
11.132 km |
10.247 km |
7.871 km |
4.3496 km |
2 |
0.01 |
0° 00′ 36″ |
town or village |
1.1132 km |
1.0247 km |
787.1 m |
434.96 m |
3 |
0.001 |
0° 00′ 3.6″ |
neighborhood, street |
111.32 m |
102.47 m |
78.71 m |
43.496 m |
4 |
0.0001 |
0° 00′ 0.36″ |
individual street, land parcel |
11.132 m |
10.247 m |
7.871 m |
4.3496 m |
5 |
0.00001 |
0° 00′ 0.036″ |
individual trees |
1.1132 m |
1.0247 m |
787.1 mm |
434.96 mm |
6 |
0.000001 |
0° 00′ 0.0036″ |
individual humans |
111.32 mm |
102.47 mm |
78.71 mm |
43.496 mm |
7 |
0.0000001 |
0° 00′ 0.00036″ |
practical limit of commercial surveying |
11.132 mm |
10.247 mm |
7.871 mm |
4.3496 mm |
8 |
0.00000001 |
0° 00′ 0.000036″ |
specialized surveying (e.g. tectonic plate mapping) |
1.1132 mm |
1.0247 mm |
787.1 µm |
434.96 µm |
A value in decimal degrees to a precision of 4 decimal places is precise to 11.132 meters at the equator. A value in decimal degrees to 5 decimal places is precise to 1.1132 meter at the equator. Elevation also introduces a small error. At 6,378 m elevation, the radius and surface distance is increased by 0.001 or 0.1%. Because the earth is not flat, the precision of the longitude part of the coordinates increases the further from the equator you get. The precision of the latitude part does not increase so much, more strictly however, a meridian arc length per 1 second depends on latitude at point concerned. The discrepancy of 1 second meridian arc length between equator and pole is about 0.3 metres because the earth is an oblate spheroid.