advanced techniques used for locating proposed construction structures
TRANSCRIPT
8/7/2019 ADVANCED TECHNIQUES USED FOR LOCATING PROPOSED CONSTRUCTION STRUCTURES
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ADVANCED TECHNIQUES
USED FOR LOCATING
PROPOSED CONSTRUCTIONSTRUCTURES
Apurva Kotkar -701030Ronak Lahoti -701031
Sampada Mane -701032
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Traditionally surveyors used theodolites for angle
measurements Also methods of triangulation were used
Distances were measured with a steel band or Electronic Distance Measurement(EDM) device to
propagate coordinates from one point to another using the technique of traversing
But problems associated with triangulations are:
-Fixation of permanent markers.
-Bearings at large distances.-Instruments used are not easily portable.
-Requires more manpower.
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However all these methods also need to have lot
of measurements within short intervals for better accuracy and needs lot of corrections.
Also the results obtained depends on the type of instrument used , skills of person using the
equipments etc. So advanced techniques like
- use of Total Station
- use of Global Positioning System (GPS)
- use of laser technology
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TOTAL STATION
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Total station is a new revolutionary system also called
as a Smart Station now a days
It is a perfect combination of TPS and GPS
There is no need for control points, long traverses or
resections
The GPS determines the positions while total stationcarries out the survey
All data is stored on the database on the Compact
Flash card
There is no need for external batteries, cables, data
loggers, etc.
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The total station consists of smart antenna on a pole
as a R TK cover
The TPS plug in battery also powers the GPS smart
antenna and R TK communication device
Due to its modular design the smart station is flexible
and has versatile purposes Thus a total station can be used for location of sites in
rural areas, for topographic survey, in remote areas
and also for boundary survey
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Real Time Kinematic (R TK)
R TK satellite navigation technique is a technique used
in land survey and hydrographic survey
It is based on the use of career phase measurements of
the GPS and GLONASS signals
A single reference station provides the real time
correction providing up to centimeter level accuracy
It uses a single base station receiver and a number of mobile units
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The mobile units compare their own phasemeasurements with the ones received from the base
station The base station re-broadcasts the phase of the carrier
that it measured, and the mobile units compare their own phase measurements with the ones received from
the base station Most land survey equipments have a built in UHF
band radio modem as a standard option
In surveying the base station is located at a known
surveyed location, a benchmark, and the mobile unitscan then produce a highly accurate map by takingfixes relative to that point
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Use of smart station for topographic survey
in remote areas Set up smart station at a convenient place where there
is a reasonably open view of the sky
At the first point P1, determine the position with R TK
Orient towards second point P2
Positions with respect to R TK are known
Smart Station will automatically transform the
coordinates of all of the detail points
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Advantages
Control points established where required by R TK
Points occupied only once
Only Smart Station is needed
Only one crew is needed
Transformations made automatically in Smart Station
The survey takes less time
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Property survey in a rural locality
There are trees and hedges along the boundary line
The nearest control points that can be used by a total
station are 5km away, but data for R T
K can bereceived from a distant GPS reference station.
The boundary is surveyed using pairs of clusters of
smart station points
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Advantages
No long traverses needed
Less set ups needed
Two people are sufficient
Uniform and higher accuracy
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Stakeout on a large construction site
A large number of markers have to be placed and
many components positioned
Control points are not required.
Smart station is set up wherever necessary while R TK
determines the position
The pairs or group of points do not have to be
connected by total station measurements The stakeout is carried faster and thus the
construction activities
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Surveying Utilities in an Urban
Environment
The positions of all manholes, covers, hydrants,distribution boxes etc. for water, gas and electricityhave to be determined
Smart station is set up at places such as at roadintersections, open spaces and even on top of the buildings
Angles and distances to be surveyed are measured
The correct circle orientation is only available after the measurements have been taken
Smart station will transform all the coordinatescorrectly and automatically.
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Both commercial and residential concrete contractors
are using robotic total stations for building layout
work
Residential foundation contractors often provide
control points for footing excavation work, then
reshoot the points for footing layout, and make a thirdtrip to locate foundation walls on the footings
Commercially, contractors use total robotic stations to
check elevations, locate columns and walls, lay out
anchor bolt patterns, and lay out utilities for eachfloor of a building
The amount of cut and fill also can be determined
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Reflector less robotic total stations can make
reflectorless measurements up to 4000 ft and prism
measurement to 23000 ft.
R TK determines the position to centimeter accuracy
within a few seconds at ranges up to 50km or more
from a reference station
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Total Station in Transportation
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Use of smart station in road alignment
More ground is covered with fewer instruments setup
Dual sensor connection allows instant switching eg.
In cases of environment change
Software is seamless for measuring points and feature
codes
Development in integrated surveying has helped in
significant time saving and increasing productivity Thus it gives good return on investments
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Trimble Access Software with Road
Module
The Trimble access field software is versatile
It is highly graphical software making survey
tasks fast and efficient The road module offers a specialized workflow
for road surveys
It simplifies the project and reduces learningcurves
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Construction of High Rise structure
The high rise structure has an ideal axis relative to thegravity vector
Three reference points are determined by GPS of the
smart station The position of an electro-optical geodesic instrument
assigned to the structure is determined relative to thethree reference points
The tilt of a real line developing from the ideal axisunder tilt effects acting on the structure is acquiredgravimetrically, more particularly with a gravimetrictilt sensor
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By acquisitions of real line and gravimetric positions
a co-ordinate system can be obtained
Thus a precise and reliable surveying procedure can
be provided to a structure
Thus any structure can be built avoiding tilt effects
and it hampers the use of ground level reference points
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Total Station in Tunnel Engineering
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Case Study:- E18 Bjorvika project in Oslo, Norway
It involved construction of under water tunnel-asubsea tunnel
It made use of the Leica total station and Leica Scanstation
The shape was a challenge as it involved curvedelements
It consisted of six elements of 100 metre long walls,1 m thick and roofs and floors 1.20 m thick
The horizontal surfaces were measured with a totalstation while vertical surfaces were measured bysingle point lines
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Laser scanner were used to scan various positions on
the inside and outside. The total station was used to measure the break lines
inside the elements
The mesh operation was easier to accomplish with
predefined break lines in the post processing phase
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Post Processing Phase
The difference between ordinary surveying and
modern laser scanning is that the survey sites
physically have to be tided up before scanning
This helps in minimizing garbage points that have to be edited out of the point cloud afterwards
When a scene is scanned, everything gets measured,
so the scene should be nice and clean
The area often has lots of scrap, scaffolding, lifts and
machinery from the building process
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In editing the concrete surface, it is irregular and it is
quite difficult to decide which points to remove andwhich to leave in
It is a part of the rough editing of the point cloud
The unwanted points are fenced
With the help of Leica cyclone editing the redundant
points are placed in their own layers instead of
deleting
Thus data can be retrieved
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GPS
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GPS
GPS, which stands for Global Positioning System, is
a radio navigation system that allows land, sea, and
airborne users to determine their exact location,
velocity, and time 24 hours a day, in all weather conditions, anywhere in the world.
GPS was created and realized by the U.S. Department
of Defence (USDOD) and was originally run with
24 satellites. It was established in 1973 .
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Three major segments of GPS
1.Space segment (SS)
2.Control segment (CS)
3.User segment (US)
The U.S. Air Force develops, maintains, and operates
the space and control segments.
GPS satellites broadcast signals from space, and each
GPS receiver uses these signals to calculate its three-dimensional location (latitude, longitude, and
altitude) and the current time.
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1.Space segment
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The space segment (SS) is composed of theorbiting GPS satellites, or Space Vehicles (SV)in GPS parlance.
The GPS design originally called for 24 SVs,eight each in three circular orbital planes, butthis was modified to six planes with four satellites each. The orbital planes are centred onthe Earth, not rotating with respect to the distantstars.
The six planes have approximately 55°inclination (tilt relative to Earth's equator) and
are separated by 60° . (angle along the equator from a reference point to the orbit'sintersection).
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The orbits are arranged so that at least six
satellites are always within line of sight fromalmost everywhere on Earth's surface.
The result of this objective is that the four satellites are not evenly spaced (90 degrees) apartwithin each orbit.
In general terms, the angular difference betweensatellites in each orbit is 30, 105, 120, and 105degrees apart which, of course, sum to 360degrees.
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2.Control segments
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The control segment is composed of
1.a master control station (MCS)
2.an alternate master control station
3.four dedicated ground antennas and
4.six dedicated monitor stations.
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3.User segments
GPS receivers
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In general, GPS receivers are composed of an
antenna, tuned to the frequencies transmitted by the
satellites, receiver-processors, and a highly stable
clock . They may also include a display for providing
location and speed information to the user.
A receiver is often described by its number of
channels: this signifies how many satellites it can
monitor simultaneously.
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How the GPS Works
A GPS receiver calculates its position by precisely
timing the signals sent by GPS satellites high above
the Earth. Each satellite continually transmits
messages that include- the time when the message was transmitted
- precise orbital information
- the general system health and rough orbits of allGPS satellites
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The receiver uses the messages it receives to
determine the transit time of each message andcomputes the distance to each satellite.
These distances along with the satellites' locations areused with the possible aid of trilateration, depending
on which algorithm is used, to compute the positionof the receiver.
This position is then displayed, perhaps with amoving map display or latitude and longitude;
elevation information may be included.
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Many GPS units show derived information such as
direction and speed, calculated from position
changes.
The receivers use four or more satellites to solve for
the receiver's location and time.
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Position calculation
Using messages received from a minimum of four visible satellites, a GPS receiver is able to determinethe times sent and then the satellite positionscorresponding to these times sent.
The x, y, and z components of position, and the timesent, are designated as [xi,yi,zi,ti] where the subscripti is the satellite number and has the value 1, 2, 3, or 4.
Knowing the indicated time when the message wasreceived tr , the GPS receiver can compute the transittime of the message as[tr-ti] .
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Assuming the message travelled at the speed of
light say c, the distance travelled or pseudo
range, pi can be computed as[tr-ti]c . A satellite's position and pseudo range define a
sphere, centred on the satellite with radius equal
to the pseudo range. The position of the receiver
is somewhere on the surface of this sphere. Thuswith four satellites, the indicated position of the
GPS receiver is at or near the intersection of the
surfaces of four spheres.
In the ideal case of no errors, the GPS receiver
would be at a precise intersection of the four
surfaces.
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Applications
Cellular telephony: Clock synchronization enables
time transfer, which is critical for synchronizing its
spreading codes with other base stations to facilitateinter-cell handoff and support hybrid GPS/cellular
position detection for mobile emergency calls and
other applications.
Disaster relief/emergency service : Depend upon
GPS for location and timing capabilities.
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Phasor measurement units: GPS enables highlyaccurate time stamping of power systemmeasurements, making it possible to computephasors.
Recreation: For example, geocaching, geodashing,GPS drawing and waymarking.
Surveying: Surveyors use absolute locations to make
maps and determine property boundaries. Tectonics: GPS enables direct fault motion
measurement in earthquakes.
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GPS Compared to Total Station
Until recently the Total Station Theodolite (TST) has
become the preferred tool for setting out of trenches,
surveying sites or topographical surveys. Frequently
in archaeological work, Now GPS has become the popular tool for many surveying professionals. It
outperformed TST when the work has to be done.
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Total station can not be used in following situations Where sites are remote and has limited access, hard
details are not available, and positioning may be
unreliable.
Where more man power is not available.
where line of sight cannot be maintained between the
instrument and prism.
where no dependency can be maintained on permanent landscape features.
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In addition, GPS may need less man power and lesstime to complete same coverage of TST. In other
words, both setting up and surveying time is
considerably reduced.
There are limitations associated with GPS. Since,this system depends on communication with satellite
system, when carrying out surveys, clear sky have to
be there. Similarly, you may notice poor satellite
signal reception when in thick forest cover or close totall buildings.
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How to locate the under water
locations using GPS
Of course a GPS doesn't work underwater, since
water prevents communication from the unit's
antenna to the GPS satellites.
So, the GPS floats on the surface, in a housingattached to the dive flag.
The diver records sufficient data to effect the
translation of the surface flag position to the
underwater site itself.
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GPS Floating on water
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Before the dive it is turned on, set to record tracks at
10 second increments, then sealed in the housing.
The flag line has been calibrated with 10 foot marks.
When the diver reaches a point he wishes to map, heallows the flag/GPS time to settle out from surface
conditions, then records depth, deployed line length,
time of day, and compass bearing of the flag line with
respect to north on his underwater notebook or slate.
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Recording on under water slate
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After returning to land, the GPS track file is dumped
to a PC computer using it's interface cable.
The flag/GPS location near the underwater site is
determined by corresponding the diver's time mark
with the GPS track of the same time.
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Then, using the depth, line length, compass data, and
a little trigonometry, the offset between the GPS
system and the diver can be calculated, and the
lat/long of the underwater object determined.
With care, the offset can be determined to well within
the GPS error itself, so the underwater object is
mapped to the accuracy of the GPS.
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The next step,usually shore side, is
to download thetrack data from theGPS, then correct
the offset errors between where theflag/GPS was andthe diver's actual
location.
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The underwater data from the slate (depth, line
length, compass heading, and time) can now be used
to find the flag/GPS location and it's offsets from theunderwater site. A corrected Lat/Long will result.
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A Case Study from Agricultural
faculty area of Tekirdag
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The campus area of Tekirdag Agricultural Faculty
was selected as research area to determine its
settlement and application plan using Global
Positioning System (GPS). The area of Tekirdag Agricultural Faculty takes part
within Tekirdag city border in Thrace Region.
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Location
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The size of Tekirda Agricultural Faculty¶s
campus area is approximately 93.7 ha according
to the official registrations.
Instruments, equipment and hardware used
An electronic theodolite of was used in survey
measurement to determine topographic and
physical characteristics of the campus area(Figure 2a).
An electronic planimeter was used to determine
the size and surrounding length of the campus
area on the plan which was drawn using theresults of measurements done by electronic
theodolite (Figure 2b).
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Th GPS d i d d i
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Three GPS, devices were used to determinecoordinates of the campus area (Figure 3). Table1 shows the technical specifications of the GPS
devices. The data obtained from the electronic theodolite
were transferred into MS Excel program in thecomputer and necessary computations were
done in this program. Data obtained from the GPS devices were
transferred into computer by RS-232 adaptor and Trackmaker software was used to work on
this data. Then, three dimensional analysis of this data were done in the computer usingArcGIS and ArcView 3D Analyst software.
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2 El t i Th d lit
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2a Electronic Theodolite
2b Planimeter
3 GPS
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Technical Specifications of GPS
:Table1
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The measurements done with GPS devices were
transferred to computer as digitized by Map
Source and Trackmaker software.
The Triangulated Irregular Network (TIN)
command in ArcGIS was used to obtain a three
dimensional view and to determine the slope of the research area on digitized data.
The principle of the TIN model is a structure
arising from point, line and area between itself
of each height value transferred from GPS andother neighbouring data.
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Area comparisons by different
methods:Table 2
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Area by Theodolite Calculations
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GPS Mapping
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Triangulated irregular network
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D i f 5 d l li
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Drawings of 5m spaced leveling
curves on the 3 D vision
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The size and surrounding length of the campus
area are calculated from title deed and the
measurement methods were different.
- minimum area 936 703 m2
- maximum area 957 434 m2 The result of the electronic planimeter and GPS
measurements were between 941 000 m2 and
947 000 m2.
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Laser Technology
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INTRODUCTION
Laser is "Light Amplification by Stimulated
Emission of Radiation".
It uses a quantum mechanical effect, stimulated
emission, to generate a very collimated ,
monochromatic beam of light.
Common light sources, such as the electric light bulb
emit photons in all directions.
Most light sources are also incoherent, i.e., there is nofixed phase relationship between the photons emitted
by the light source.
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By contrast, a laser emits photons in a narrow,
well-defined beam of light
The light is often near-monochromatic, consisting
of a single wavelength or color is highly coherent
and is often polarised.
Laser system generally consists of three important parts:
a) An energy source (usually referred to as the
pump or pump source) : they provides energy tothe laser system.
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Examples of pump sources include electrical
discharges, arc lamps, chemical reactions and even
explosive devices.
b) A gain medium or laser medium : determining
factor of the wavelength of operation, and other
properties of the laser
It is excited by pump source for spontaneous and
stimulated emission of photons leading to the
phenomena of optical gain or optical amplification
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Examples of different gain media include:
a) Liquids: such as dye lasers.
b) Gases: carbon dioxide, argon, krypton and
mixtures such as helium-neon.
c) Solids: crystals and glasses
d) Semiconductors : in which the movement of electrons between material with differing dopant
levels can cause laser action.
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3) System of mirrors, forming an optical
resonator :is two parallel mirrors placed around
the gain medium.
Light reflected by the mirrors back into the
medium, where it amplified by stimulated
emission.
The light may reflect from the mirrors (and thus
pass through the gain medium) many hundreds of
times before exiting the cavity.
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LASER USED IN CONSTRUCTION
Two types of laser beams used in construction,
visible beam and infrared
Visible beams (635nm to 532nm for the Green
Beam®) are generally used in the interior and
utility/pipe markets.
Infrared lasers are used in general construction
(concrete, small excavation), and heavy
earthmoving markets.
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The construction laser advantage
lasers are replacing many traditional tools.
Qualities inherent in lasers have overcome many
of the limitations of traditional tools
Ex: Contractor places a rotating laser in its
vertical position so the beam sweeps across the
ceiling, down the far wall and across the floor.
From that single setup he or she can hang a wall
bracket from the ceiling, the floor, and place the
studs exactly vertically by themselves.87
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The savings realized from using a laser is two-fold:
first the setup time is reduced by at least 50%
because same reference is used for the floor, ceilingand everything in between.
Second, a two person job was reduced to a single
person, saving labor so finishing job faster.
construction laser types
Interior laser : Using visible beams, they are used to hang ceiling
grids, align and mount floor and ceiling brackets for
walls, align studs.88
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Their visible beams replace the need for
cumbersome bubble vials, ceiling string, and chalk
lines that require time consuming setups
General Construction Lasers:
Using infrared beams, GC lasers are lasers used for
exterior applications like, Setting concrete forms,checking grade on flat pads, checking depth of footers
and trenches, and even providing elevation indication
for laser receivers mounted on excavators, backhoes.
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Sl /M hi C t l L
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Slope/Machine Control Lasers:
Using high power infrared, they are used for Land
leveling , road and runway construction requireslope for rain drainage, long trenching jobs requiring
a constant fall for the pipes.
Pipe Lasers:In this case visible laser light used for laying pipes
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3D LASER SCANNING
Technique used to gather data about an object or
environment used to create a 3D model .
Laser scanners emit a narrow laser beam and thenreceive and process the signal returned by reflection
from the object.
Depending on the model selected, laser scannerscan measure between 100 and 500,000 points per
second. The range varies between 20 and 100 metres
, with an accuracy of between ± 1mm and 5cm.91
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devices generate a µpoint cloud¶ of hundreds of
thousands of surveyed points.
They used to create an exact but rudimentary 3D
model of the object, which can be converted by
software into a fully-fledged 3D model, recognizable
by anyone.
The Technology
It is suitable for rapid and detailed non-contact
measurement and mapping; the 3D image obtained
can then be analyzed and edited off-site.
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The method is particularly suitable for modeling
highly complex sites and objects made up of irregular
shapes.
3D SCANNING ±APPLICATION IN TUNNLE
Professional SurveyorMagazine - December 2009
The Turkey Creek Diversion Tunnel is very
impressively constructed circa 1920 at 28 feet in
diameter and 1,400 feet long, concrete-lined, and indesperate need of repair.
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Turkey Creek runs under Interstate 35 in Kansas and
into the Kansas River.
The nearly 100 years of diverting massive amounts of
water from it (and several notable natural disasters)
had taken its toll on the tunnel.
Task given to surveyor was to document the existing
conditions of the tunnel for determining the extent of
damage and designing the much-needed repairs.
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Steps carried for this case as follows :
Step 1 : perform a terrestrial lidar scan of theentire length of the tunnel.
Step 2 : with the help laser scanner ,map the entire
circumference of a tunnel at a very high accuracyand speed, producing a 3D cloud of point data.
Step 3 : produce cross sections at any point in the
tunnel by using data
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The scanner
Lidar technologycaptures 3D survey-
grade data points at a
rate of up to 50,000
points per second and arange of up to 300
meters to a 90 percent
reflective surface.
. The medium the scanner uses is a pulsed or
time-of-flight laser.
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It uses two mirrors to direct the laser throughout its
360° x 270° field of view.
The scanner we used, also possesses a survey-
grade dual axis tilt compensator, it has the ability to
acquire this data at a 6mm positional accuracy of
each individual point.
The scanner has an onboard digital camera that
captures low resolution digital photos.
The photos are output, through a program inside
the software, into a 360° x 270°panoramic digital
photograph.98
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This allows the technician to look at photos when
drafting as well as the point cloud.
The pixels from the photos can
be mapped to the
corresponding point in the point
cloud, creating a photorealistic 3D model
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Scan plan
Transfer survey control from the surface of thetunnel to invert.
for that purpose they deployed global positioning
systems (GPS) and robotic total stations to transfer control information into the invert of the tunnel
dewatering effort was taking place in the way of a
coffer dam and installation of a 48´ pipe to slow theflow and carry the water out of the invert to
establish a working environment.
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Once the invert had been dewatered, they sent
laser scanning team into the tunnel.
Plan was to traverse through the tunnel, making
a setup approximately every 200 to 400 feet
Set scanning resolution at 0.30 feet in the
horizontal and 0.10 feet in the vertical at a range
of 300 feet from the scanner.
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Thi d ti i t l 30 i t
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This made scan time approximately 30 minutes
per setup.
The entire tunnel was scanned from six
locations.
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Offi P i
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Office Processing
Used Lecia Cyclone software to produce 2D
cross sections at a rate of approximately one cross
section per hour.
Once the cross sections produced the software
creating the 3D wireframe
.
Then exported the wireframe to a CAD-compatible
format.
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3D SCANNING ±APPLICATION UNDER SEA
The Girassol Oilfield
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Girassol is the world¶s largest µFloating Production,
Storage and Offloading vessel¶.
With a hull 300m long, 60m wide and 30m deep, this
ship-like vessel is permanently but flexibly moored to
sixteen µsuction anchors¶ on the unstable seabed in1,350 metres of water 210km north-north-west of
Luanda, the capital of Angola
The vessel is connected to a large number of
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The vessel is connected to a large number of
drilling platforms pumping oil from the gigantic
Girassol reservoir, some 1,200 metres beneath theseabed.
Operators of Girassol, Total Exploration
Production Angola, wish to exploit new oilfieldsin the vicinity, entailing a doubling of production
and processing capacity onboard the existing
vessel.
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Survey Team at Work
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Survey Team at Work
The survey carried out with reflectorless total
station and two laser scanners.
During the seventeen days spent onboard, 101 flat
adhesive targets were measured in ship coordinatesusing the total station so as to provide control for
laser scanning from around seventy different scanner
stations; a total of more than 100 million points were
scanned.
Accuracy, after combining all the individual models
in Real Works Survey software, was ± 20mm.107
Successful Outcome
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Successful Outcome
One week of post-processing included combiningthe datasets, cleaning point-clouds and exporting
the data , installing the results in systems to make
3D modeling.
Difficulties during survey:
µstatic¶ deformations caused by loading and
unloading the vessel in the course of the job.
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dynamic deformations caused by waves and
associated motion of the ship.
Continuous operation of the vessel itself and of
the plant installed on it caused unaccustomed
vibrations
These, together with relative movements between
the various components of the deck assembly,
made for unfavourable observing conditions.
Tropical conditions of temperature and humidity.
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