investigating gis technologies - group 01cw final presentation

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