contribution of gps in surveying quarries quarries el hassanesemlali, prof ... traverse (several...
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FIG Working Week 2011
Bridging the Gap between Cultures
Marrakech, Morocco, 18‐22 May 2011 1
FIG WW 2011
Institut Agronomique et Vétérinaire Hassan II
School of Geomatic Sciences & Surveying Engineering
Bienvenue Welcome
CONTRIBUTION OF GPS IN
SURVEYING QUARRIESEl Hassane SEMLALI, Prof
Mourad BOUZIANI, Prof
Hicham OUMIMA & Hicham ANJJAR, Eng
Morocco.
Research Project / DAR [email protected]
www.iav.ac.ma
� INTRODUCTION
� OBJECTIVE
� EXPERIMENTAL STUDY
� RESULTS AND DISCUSSION
� CONCLUSION
OUTLINE
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
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FIG Working Week 2011
Bridging the Gap between Cultures
Marrakech, Morocco, 18‐22 May 2011 2
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
� GPS and total station play an important
role in collecting surveying data
� GPS system offers a three-dimensional positioning in a global reference frame, at any time, regardless of the meteorological conditions and over the globe
INTRODUCTION
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SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
� Quarries involve an important industrial activity� Provide important materials for building and public works� Contribute to economic development and land planning as well as they are a great source of income
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INTRODUCTION
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FIG Working Week 2011
Bridging the Gap between Cultures
Marrakech, Morocco, 18‐22 May 2011 3
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MAI 2011FIG MARRAKEC 2011
terrestrial surveying methods
observation duration
problem of
visibility
number of people
decrease in
production
time lost
INTRODUCTION
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
� Experiment the use of GPS in surveying quarries in order to
� Determine the volumes of rubble using two surveying methods
� Test GPS contribution in improving the quality and performance
� Compare the results in terms of volumes determinations / The total station
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OBJECTIVE
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FIG Working Week 2011
Bridging the Gap between Cultures
Marrakech, Morocco, 18‐22 May 2011 4
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
� Orthometric heights: H = h - N
� Small areas, flat terrain
∆N = ∆h – ∆H
� If we consider ∆N ≈ 0
� Therefore : ∆h ≈ ∆H
� Orthometric heights:
Hpt = Href + ∆href-pt
MAI 2011FIG MARRAKEC 2011
GPS AND LEVELLING
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
The study sites� Sites are two quarries of marble (or limestone) located in the northern region of Morocco� These careers are open, and were operated over several years.
EXPERIMENTAL STUDY
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FIG Working Week 2011
Bridging the Gap between Cultures
Marrakech, Morocco, 18‐22 May 2011 5
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
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Mission planification
GPS surveying
GPS Data treatment
determination of cubature. COVADIS profile &prism
Comparison
Analysis
Total station
EXPERIMENTAL STUDY
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
MAI 2011FIG MARRAKEC 2011
Survey using total station
� The monitoring every six months.
� For each career, several new points were
determined in order to fully cover the career
by known points in three dimensions
� Point determination: traverse (several
stations)
� Nb of people: 5
EXPERIMENTAL STUDY
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FIG Working Week 2011
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GPS SurveyCharacteristics of GPS receiver reference point :
• Highest point of the route
• Stable: there is no mining in its closure
• Free of obstacles to assure good reception of GPS signal
• Far from site’s installations
GPS observations :
• Number of satellites> = 4
• PDOP <7
• Stop and go mode for mobile receiver
• Reinitialization time is 20 minutes (signal interruption).
• Observation time: 15 seconds
EXPERIMENTAL STUDY
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
MAI 2011FIG MARRAKEC 2011
Analysis
Volume
Computation methods
Profile Prism
Surveyingmethods
GPS Total Station
RESULTS AND DISCUSSION
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FIG Working Week 2011
Bridging the Gap between Cultures
Marrakech, Morocco, 18‐22 May 2011 7
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
Comparison methods of calculating cubature (prism & profile)
First career:
By total station:
�The differences between cubaturesobtained for various levels by the two methods vary between 1 m3 and 188 m3.
Using GPS
� The differences between cubatures obtained for various levels by both methods vary from
2 m3 to 12 m3.
� After analysis, we can see that the results of cubature for each kind of survey, using the two methods are very closer.
� Ccl: the methods of calculating cubature by profiles or by prism lead to similar results.
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RESULTS AND DISCUSSION
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
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0
50000
100000
150000
200000
250000
300000
GPSST
GPSST
GPSST
GPSST
P5-P1P5-P2
P5-P3
P5-P4
Cubatures using two methods (m³)
First career
profils
prismes
RESULTS AND DISCUSSION
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FIG Working Week 2011
Bridging the Gap between Cultures
Marrakech, Morocco, 18‐22 May 2011 8
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
MAI 2011FIG MARRAKEC 2011
Comparison between results of two survey methods
(GPS vs total station)
First Career : the differences between level P5, the current state of the this career and the precedent surveys (levels P4, P3 , P2 and P1).
RESULTS AND DISCUSSION
Cubature using GPS & Total station
GPS (m³) Total ST (m³) mixed (m³)
P5-P1 294038 280055 297924
P5-P2 236197 218748 234552
P5-P3 153532 132788 142368
P5-P4 39289 39387 41416
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
MAI 2011FIG MARRAKEC 2011
Comparison between results of two survey methods (GPS vs total station)
Analysis : First Career
� Results of cubature from the two surveys are different.
�The result obtained by GPS survey is greater compared to that obtained by total station.
� Results of cubature between levels P4 and P5 are closer to each other
�The difference between the results of cubature using GPS and total station is close to 2 ‰.
Results of cubature obtained by GPS and mixed survey are close to each other. The difference does not exceed 5℅ of the total cubature.After these remarks we can say that the GPS survey compared to the total station , represents better the first career.
RESULTS AND DISCUSSION
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FIG Working Week 2011
Bridging the Gap between Cultures
Marrakech, Morocco, 18‐22 May 2011 9
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
MAI 2011FIG MARRAKEC 2011
Comparison between results of two survey methods (GPS vs total station)
Second Career
� Differences represented here are
between levels P1 and P5.
The analysis shows that:�There is 12% difference between cubature obtained using GPS survey and that obtained using total station survey.� GPS data are insufficient compared to that of total station, so it is not adequate to represent this career.� we can conclude that the total station survey, compared to GPS survey, represents better this second career.
626689
708308
689345
GPS (m³)
Total ST (m³)
mixed (m³)
RESULTS AND DISCUSSION
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
MAI 2011FIG MARRAKEC 2011
Comparison between results of two survey methods (GPS vs total station)
� The major problems encountered during the survey of this career by GPS, were caused by satellite geometry.
�There was a very large area of the career not surveyed because of the depth of certain of its zones.
�Consequently, the PDOP was increasing rapidly. For that purpose we need to know the density of surveyed points in each case.
RESULTS AND DISCUSSION
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FIG Working Week 2011
Bridging the Gap between Cultures
Marrakech, Morocco, 18‐22 May 2011 10
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
Zone C
High PDOP
Zone B
Mean PDOP
Zone A
Good PDOP
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
MAI 2011FIG MARRAKEC 2011
Analysis of density of points
� The accuracy of a Digital Elevation Model (DEM) depends on the density of measures adapted to the variation of the terrain.
�In a rough terrain, we need a survey that describes better its characteristics.
� The density of points over 400 m, is :
RESULTS AND DISCUSSION
GPS Total ST
First career 2.41 1.07
Second career 1.80 2.02
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FIG Working Week 2011
Bridging the Gap between Cultures
Marrakech, Morocco, 18‐22 May 2011 11
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
MAI 2011FIG MARRAKEC 2011
Density of points
�Therefore, the density of points in the first case is better with GPS survey
�while it is better using Total station in the second career.
�We can therefore explain that the differences in results of cubature between the total station and GPS are due to the density of the surveyed points.
�When density is good the cubature defines well the terrain.
RESULTS AND DISCUSSION
GPS Total ST
First career 2.41 1.07
Second career 1.80 2.02
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
Total station and GPS to survey two different quarries. Considering the obtained results we can draw the following conclusions:
� The profiles and prism methods of calculating cubature lead to similar results.
The use of GPS to survey a career has certain advantages:
� In a clear and less rugged career, the use of GPS to survey will save a significant amount of time.
� The rate of survey is limited by the speed of displacement of the mobile receiver.
� Using a single fixed reference station for multiple mobile receivers reduces costs and time.
� The GPS represents the advantage that the intervisibility is not necessary to make survey.
� The GPS also minimizes the number of people needed during survey operations.
CONCLUSION
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FIG Working Week 2011
Bridging the Gap between Cultures
Marrakech, Morocco, 18‐22 May 2011 12
SCHOOL OF GEOMATIC SCIENCES & SURVEYING ENGINEERING
GPS limits/problems
� The multipath and the interruption of signals for deep careers.
The use of a total station to survey a career presents certain disadvantages:
� we need several stations to cover a very large area of a career.
� The use of total station is handicapped by problems of intervisibility which influences on time and cost operations.
�The total station survey is time consuming.
�The density of surveyed points is the most critical factor� Complementarities between the total station and GPS will certainly give best and complete density of the terrain, therefore good cubature results.
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CONCLUSION
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