ADVANCED TECHNIQUES USED FOR LOCATING PROPOSED CONSTRUCTION STRUCTURES

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

1



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.

5



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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7



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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17



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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Applications



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



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



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



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

Th i li d f i l i t f ld



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

Th i i ibl b l h d f



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



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



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



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.



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



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.



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



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



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.

ADVANCED TECHNIQUES USED FOR LOCATING PROPOSED CONSTRUCTION STRUCTURES

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