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Group 01CW Brandon Nussey, Bryan Dewar, Ronald Darraugh, & Simon Sweeney
• Introduction • What is GIS? • GIS Applications • RTK Rovers and Requirements • Localizing a jobsite
• Approach • Results • Conclusions • Recommendations • Acknowledgements • Questions?
• Setting up GPS jobsites is time consuming
• Using an RTK GPS base and rover, a form of GIS technology; we created a digital file and calibrated a major portion of Ottawa’s geography
• By doing this, we’ve eliminated the need to calibrate individual jobsites for each new project
A Geographic Information System is: “a system for marrying data sets with geography”
Figure 1. The basic concept of GIS software.
Real Time Kinematic (RTK) Base and Rover
Satellite
Rover
• Commonly referred
to as GPS
• Three communication channels
• +/- 15mm-25mm location accuracy POTENTIAL
Base Station
Figure 2. GNSS RTK base and rover system.
Surveying
Figure 3. A surveyor. Figure 4. A mobile rover.
- Feature Layout - Stake out - Real-time “cuts”
and “fills”
- Topographic surveys or “TOPO’s”
- “As-builts” - On-site volume and
area calculations
Site Works
AutoCAD Drawings and Plans
Precise Survey Control Points
Figure 5. A typical survey control monument. Prepared and provided by
engineers, consultants Contain spatial information and line work Used to create designs, maps, and everything visible on data collector screen
Installed by qualified land surveyors Provided to contractors by City of Ottawa, MTO, etc. Used to localize or calibrate jobsites
• Published coordinates are like a really big game of Battleship… but where are the labels?
• 3-dimensional, curved surface of the Earth is being represented on flat, 2-dimensional plans
• Distortion is INVEVITABLE • Shapes and sizes can become
misrepresented
Figure 6. A ripped orange peel representing data transfer distortion.
• Control points “pin” the digital plans, to the Earth’s surface
• “Iron out the wrinkles” • Done through CALIBRATION
Figure 9. Range of base station.
• Find reliable network of control points • Measure in control points • Testing: practical and theoretical
Point ∆ Northing (m) ∆ Easting (m) ∆ Elevation (m)
168 0.042 0.013 0.026
142 0.050 0.009 0.038
143 0.032 0.020 0.010
145 0.035 0.002 0.010
73 0.055 0.036 0.049
3 0.014 0.021 0.014
170 0.050 0.003 0.011
171 0.042 0.005 0.012
59 0.037 0.005 0.008
173 0.036 0.008 0.014
Average= 0.039 0.012 0.019
Table 1. Practical testing results.
Job Scale Factor Rotation
Angle (°,',") Horizontal
Residual (m) Vertical
Residual (m) ∆ Scale Factor ∆ per 100m
(m) ∆ per 1000m (m)
Individual site average 0.999914835 0° 33' 52.3" 0.020 0.036 0.0001068955 0.01068954 0.1068954 City-wide calibration 0.999996488 0° 00' 1.0" 0.017 0.007 0.0000035118 0.00035118 0.0035118
Table 2. Individual job site calibrations vs. master calibration.
• Horizontal and vertical accuracy below 40 mm • Accurate enough for many construction applications
It’s good!
Give it a try! Waiting for issued control points = time consuming
Searching for control points = time consuming Calibrating individual sites = time consuming
TIME = MONEY
Francesco Tangorra Patrick Dawson Marieke Kalkhove Federico Fernandez
TJ Hendriks Pierre Boivin Bob Lefebvre Jacques Perriard Jean-Francois Goulet Justin Vanhecke