Terrestrial and Numerical Phot.-1

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ITU Photogrammetry Division

TERRESTRIAL & NUMERICALPHOTOGRAMMETRY

Assoc.Prof. Dr. Dursun Z. SEKER, Res. Asist. Zaide DURAN


PHOTOGRAMMETRY

Photogrammetry is, a system in which an object or anevent in time and space is recorded onto a sensitized filmor plate by means of appropriate camera or other imagingsystem, and in which the subsequent image is measured inorder to define, portray, digitize or in some way classify the

object or event.Some of nonmapping application of photogrammetry aremade in the areas of medicine, dentistry, architecturearcheology, experimental analysis of structures hydraulics,ship building, animal husbandry, deformation of dams,glacier and earth slide movements, vehicle motion, missiletracking, accident reconstruction and uderwater events.



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•Assumes the camera produces a perfect centralprojection,•There must be no deviation of light rays passing throughthe lens of the camera,•The image medium at the focal plane of the camera mustbe a rigid, planar surface,•The mathematical relationship between the object andthe image is known as the principle of collinearity,•The principle of collinearity embraces the six degrees offreedom of the camera: three translations and threerotations,•Departures from the central projection can be modelledas systematic errors in the collinearity condition.

The Principle of Photogrammetry


Its most important feature is the fact, that the objects are measured withoutbeingtouched. Therefore, the term “remote sensing” is used by some authorsinstead of “photogrammetry”. “Remote sensing” is a rather young term, whichwas originally confined to working with aerial photographs and satellite images.Today, it includes also photogrammetry, although it is still associated rather with“image interpretation”.

Principally, photogrammetry can be divided into:

1. Depending on the lense-setting:

•Far range photogrammetry (with camera distance setting to indefinite),

•Close range photogrammetry (with camera distance settings to finite values).

2. Another grouping can be:

•Aerial photogrammetry (which is mostly far range photogrammetry),

•Terrestrial Photogrammetry (mostly close range photogrammetry).



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The applications of photogrammetry are widely spread. Principally, it isutilized for object interpretation (What is it? Type? Quality? Quantity)and object measurement (Where is it? Form? Size?). Aerialphotogrammetry is mainly used to produce topographical or thematicalmaps and digital terrain models. Among the users of close-rangephotogrammetry are architects and civil engineers (to supervisebuildings, document their current state, deformations or damages),archaeologists, surgeons (plastic surgery) or police departments(documentation of traffic accidents and crime scenes), just to mention afew.


Single Camera

•2D information only•application limited to planar objects•precision dependent on image scale•no reliability

Close-range Camera Stereopair

•minimum configuration for 3Dinformation•widely used for aerial and close range•precision dependent on image scaleand base to height ratio•minimal reliability

Photogrammetric Techniques



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Technique that uses photographs for mapmaking ands ur ve yi ng. A s e a rl y a s 1 8 5 1 t he F re nc h i nv en to r A im éLaussedat pe rceived the possib il i ti e s o f the appl icat ion of the newly invented camera to mapping, but i t was not unt il50 years la ter tha t the technique was successfullyemployed.

I n the decade before World War I , terrestrialpho togrammet ry, a s i t came to be known l a t er, was widelyused; dur ing the war the much more effec tive technique of a er ia l p ho to gra mm et ry w a s i nt ro du ce d. A lt ho ug h a er ia lphotogrammetry was used pr imar i ly for mi l i tary purposesu nt il t he e nd o f Wo r l d Wa r I I , t he re af te r p ea ce ti me us esexpanded enormous ly. Pho tography is today the p r inc ipa lm etho d o f m ak in g m ap s, e sp eci al ly o f i na cc es si bl e ar ea s,and is also heavily used i n ecological studies and inforestry, among other uses.



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From the a i r, la rge areas can be photographed quickly us ingspecia l cameras, and bl ind areas , h idden f rom terres tr ia lc am er as , a re m in im iz ed . E ac h p h ot og r ap h is s ca le d, u si ngmarked and known ground reference points ; thus , a mosaicca n b e c on st ru ct ed t ha t m ay i nc lu de t ho us an ds o f photographs . Plot t ing machines and computers are used toovercome complications.

Ins trument s used in pho togrammetry have become verys op hi st ic at ed . D ev el op me nt s in t he s ec on d h al f o f t he 2 0t h

century include satel l i te photography, very large scalephotographs, automatic visual scanning, high-quali ty colourphotographs , use of f i lms sens it ive to radia t ions beyond thevisible spectrum, and numerical photogrammetry.




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Analogue: A pair of photographsare placed in a mechanical/opticaldevice called a stereoplotter. Anoperator physically adjusts theorientations of the photographs to

match the exposure situation.Detail and heights are traced on aplotting table by a directmechanical linkage.

Photogrammetric Processing Techniques



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Analytical: Single or pairsof photographs are placedin an X-Y measuring stagewhich digitally recordsimage coordinates. Mono orstereo comparators aremanually driven whilstanalytical plotters are semi-automated. Recordedmeasurements arecomputer processed andthe information registered ina CAD database.



Digital Image: Single or pairs of digitalimages are loaded into a computer withimage processing capabilities. Theimages may be from satellite orairborne scanners, CCD cameras or

are conventional photographs capturedby a line scanner. The images areeither displayed on the screen foroperator interpretation, enhanced byimage processing or subjected toimage correlation in order to form adigital elevation model or extract detail.




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Fiducial marks are small targets on the body of metric cameras.Their positions relative to the camera body are calibrated. Thus,they define the image co-ordinate system; in that system, theposition of the projection centre is known. Form as well asdistribution of fiducial marks depend on the manufacturer. If amateur cameras are used, the images of corners of the cameraframe on the negatives can be used instead of fiducial marks.

Fiducial MarksFiducial Marks



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TERRESTRIAL PHOTOGRAMMETRY

When ground-based cameras are employed, the termterrestrial photogrammetry is used. This term has beenhistorically applied to the system of surveying and mappingfrom phototographs taken at ground stations. Terrestrialphotogrammetry can be further classified;

• as close-range photogrammetry if the camera-objectdistance is somewhere between 1:10 m to 100 m,

• as macrophotogrammetry if the camera-object distance is inthe 0.10 to 0.01 m range,

• as microphotogrammetry when the photos are exposedthrough a microscope.



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A photographic image is a „central perspective“. This implies, thatevery light ray, which reached the film surface during exposure,passed through the camera lens (which is mathematically consideredas a single point, the so called „perspective center“). In order to takemeasurements of objects from photographs, the ray bundle must bereconstructed. Therefore, the internal geometry of the used camera(which is defined by the focal length, the position of the principalpoint and the lens distortion) has to be precisely known. The focallength is called „principal distance“, which is the distance of theprojection center from the image plane s principal point.

PHOTOGRAPHING DEVICES; CAMERAS

Depending on the availability of this knowledge, the photogrammetristdevides photographing devices into three categories:


They have stable and precisely known internal geometries andvery low lens distortions. Therefore, they are very expensivedevices. The principal distance is constant, which means, that thelens cannot be sharpened when taking photographs. As a result,

metric cameras are only usable within a limited range of distancestowards the object. The image coordinate system is defined by(mostly) four fiducial marks, which are mounted on the frame of the camera. Terrestrial cameras can be combined with tripods andtheodolites. Aerial metric cameras are built into aeroplanesmostly looking straight downwards. Today, all of them have animage format of 23 by 23 centimeters.

Metric Cameras



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If an object is photographed from two different positions, the line betweenthe two projection centers is called “ base ”. If both photographs haveviewing directions, which are parallel to each other and in a right angle tothe base (the so called “ normal case ”), then they have similar properties asthe two images of our retinas. Therefore, the overlapping area of these twophotographs (which are called a “ stereopair ”) can be seen in 3D,simulating man´s stereoscopic vision.

In practice, a stereopair can be produced with a single camera from twopositions or using a stereometric camera. A stereometric camera inprinciple consists of two metric cameras mounted at both ends of a bar,which has a precisely measured length (mostly 40 or 120 cm). This bar isfunctioning as the base. Both cameras have the same geometric properties.Since they are adjusted to the normal case, stereopairs are created easily.

Stereometric Camera


The photogrammetrist speaks of an „amateur camera“, when theinternal geometry is not stable and unknown, as is the case with any„normal“ commercially available camera. However, also these canbe very expensive and technically highly developed professionalphotographic devices. Photographing a test field with many control

points and at a repeatably fixed distance setting (for example atinfiniy), a „calibration“ of the camera can be calculated. In this case,the four corners of the camera frame function as fiducials. However,the precision will never reach that of metric cameras. Therefore, theycan only be used for purposes, where no high accuracy is demanded.But in many practical cases such photography is better than nothing,and very useful in cases of emergency.

Non-metric (Amateur) Cameras



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Digital Cameras

Photography can be taken with avariety of cameras; however, theresult must be digital image files.Digital cameras work the best forschedule and efficiency, with noloss of accuracy. The resolution of the cameras defines the fieldprocedures to be used, not the final

accuracy. Generally, lower cost,lower resolution cameras take morelabor to get the same accuracy ashigher resolution cameras. Vexcelcan assist in determining the bestcamera for your particular needs.


CAMERAS IN TERRESTRIALPHOTOGRAMMETRY

Two basic camera types are employed in terrestrialphotogrammetry. These are; metric cameras and non metriccameras.

Metric cameras are designed and calibrated specifically forphotogrammetric measurement. It has a known and stableinterior orientation and is usually a fixed-focus camera. Theyalso contains fidicual marks with which to recover the interiororientation.

Nonmetric cameras are represented by a variety of fairly high-quality hand-held cameras used by amateur and professionalphotographers to take good pictorial quality.



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TERRESTRIAL METRIC CAMERAS

The photographs for terrestrial potogrammetry are usuallytaken with the cameras in fixed positions, the elements of outer orientation being frequently determined by fieldsurvey. Photographs at large distances, camera to object, areonly used in special cases, for example for topographicsurveys by expeditions and for glaciological research. Detailphotographs in hilly areas, e.g. for the constructions of hydroelectric power stations of for quarry surveys, border onclose-range photogrammetry in which the camera is focusedon finite distances and the depth of field has to be considered.


GENERAL DESIGN OF TERRESTRIAL METRICCAMERAS: Stereometric Camera

Stereometric Camera consistof two cameras fixed relative toeach other in the normal casewith, usually, a fixed base. Themost common base is 120 cm,for object distances is from 5 to25 m. They are designed forthose cases where a simplephotogrammetric arrangementis suitable., for example trafficaccident or simple surveys of building facades. Fixed-basecameras baselengths of 40 cmand 200 cm also exist.

Systematic diagram of a stereometric camera.



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GENERAL DESIGN OF TERRESTRIAL METRICCAMERAS: Independent Metric Camera

These camerasare usedwhenevermaximumaccuracy isrequired and the

base/distanceratio must becarefullyconsidered. Systematic diagram of a an

independent metric camera.


Stereometric Cameras Independent Metric Camera





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FLOWCHART OF PHOTOGRAMMETRIC MAP PRODUCTION

Reconnaissance(trying for discovery)

Base Map

Marking on the Ground Photogrammetric Triangulation

Establish of GroundControl Point

AuxiliaryData Image Definition

Stereo Evaluation Single Image Evaluation



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Stereo Evaluation Single Image Evaluation

Numerical (Digital) Data Stereo P lotting

Process Cartographic Process

Analogue MapOrthophoto

PrintingDigital Map Photo Map

Mosaic

Rectification


TERRESTRIAL ANDNUMERICAL

PHOTOGRAMMETRY

Dursun Z. ªeker



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AREAS OF APPLICATIONS OF CLOSE-RANGEPHOTOGRAMMETRY

The ever-expanding areas of application of close-rangephotogrammetry can be grouped into three majorareas: architectural photogrammetry, biomedical andbioengineering photogrammetry (biostereometrics)and industrial photogrammetry.


ARCHITECTURE

It is noteworthy that the very first measurements ever made byphotogrammetry (in the middle of the 19 th century) had to dowith monuments. It is also a fact that the term“photogrammetry” was introduced by an architect,Albrecht Meydenbauer, who made his first photogrammetricsurveys in 1867. For over century, photogrammetric methodsand equipment have continued to evolve. More recently, thefield of architectural application of photogrammetry hasundergone considerable expansion both in scope and diversity.



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SURVEYS OF HISTORICAL MONUMENTS

Photogrammetric surveys of historic monuments can begrouped in three major categories:

v Rapid And Relatively Simple Surveysv

Accurate and Complete Surveysv Very accurate surveys.


Operational Procedures

Procedures for all of the above-discussed types ofphotogrammetric surveys are well established anddocumented. Independent stereopairs of photographs aretaken either horizontally, vertically or at some inclinationusing the camera(s) most suitable for the individual project.Base-to-distance ratio is kept rather small (1/5 to 1/15).External controls are kept as simple as possible (such asnumber of distances and checks on the levelling bubbles ofthe camera). In case of complex object, however, a network ofreference points is necessary. Camera stations are normallylocated on the ground, on scaffoldings, on nearby buildings,on a hydraulic lift truck or even in helicopters, which aresometimes used to take horizontal photographs of the upperportions of tall buildings.





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Economic benefits of photogrammetricapproach

$ Measurement time on the object is reduced by %90 - %95,$ Saving in manpower,$ Reduce machine and time for blade machining throughoptimisation of the metal removal rate,

$ Reduced material expenditure in the propeller castingmanifacture through optimised molds,$ A cut in recycling time for non-ferrous metals,$ Shorter production time for propeller manufacture.


ü Automobile Constructionü Mining Engineerü Machine Constructions

ü Objects in Motionü Shipbuildingü Structures and Buildingsü Traffic Engineering

Examples of Industrial Applications





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An Example Drawing of Old City Silhoutte of Istanbul


Hagia SophiaPhotogrammetric Record ofa World Cultural Heritage

The Haghia Sophia in Istanbulbelongs with its unique domeconstruction to the outstandingand extraordinary architecturalstructures in the whole world.Build between 532 and 537 duringthe Byzantine Impair Justinian(527-565), it reflects the sum of allexperiences and knowledge ofthe classical antiquity and it isone of the important monumentsof the world heritage. HaighaSophia considered as the firstand the last unique application interms of its architecture,magnificence and functionalityhas been inspiration for Ottomanmosque on the basis of givingopinion, and is product ofsynthesis of west and east. Theart is one of the wonders of theworld remained until now.



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The Conservation and Restoration Branch

of Historical Buildings asked thePhotogrammetry Division of the IstanbulTechnical University to prepareorthophotos of the Hagia Sophia. Togetherwith the Institute of Photogrammetry andRemote Sensing of the Vienna University ofTechnology, it was decided to create a highquality 3D model of the dome, so that theobtained results can later be also used inan “Hagia-Sophia Information System”.This Information system has the duty tocollect all the information about thebuilding and will be a useful guide foreveryone. As one result a 3D photo-modelwas generated and stored using the dataformat VRML (Virtual Reality ModelingLanguage). This paper describes themeasurement process, the generation ofthe 3D model, the production of theterrestrial orthophotos and the setup of aninformation system.


Vrml model of Hagia Sophia





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The houses built againstthe palace valls formpart of a complex thatincludes the fountaindated 1810 that gives thestreet its name and acistern forming part ofthe chain of great water

depots from the Romanperiod, the wholereflecting the characterof a city that has servedas capital ofthree great empires.

SOÐUKÇE ªME SOKAÐI


SOÐUKÇE ªME SOKAÐI



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Obtaining of Facade Plan of Dolmabahçe Palaceby Digital Photogrammetric Techniques

The aim of the project was to make facadeplans of Dolmabahçe Palace with a scale of1/100, 1/50, 1/20 and 1/10. A preliminarystudy was done and control points weresignalized. By the help of surveyingmethods, ground control points coordinateswere measured. Photographs were takendue to a Study Plan, and were scanned.Evaluation was done using digitalphotogrammetric software, PICTRAN. Afterinterior and exterior orientation, points weremeasured on oriented photographs, andbundle adjustment was used. Informationproduced in Pictran was transferred intoAUTOCAD system. Cross-section plans wereobtained by conventional methods.


Obtaining of Facade Plan of Dolmabahce Palace





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Seniye Sultan Mansion


Amcazade Hüseyin Paºa Mansion

The only survivor ofthe old, wood-builtwaterside residencesis the AmcazadeHüseyin Paºa Mansionon the coast atKanlýca. In fact only a

part of this greatmansion, the T-shaped receptionroom with its greatwindows overlookingthe Bosphorus,remains.



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Unfortunately its walls,which are embellishedwith painted and goldleaf designs, havedeteriora-ted rapidlyduring the last 50 yearsbecause of neglect. Inthe middle of this roomis a marble pool andover it, a domed roofbearing traces of itsformer magnificence.



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Photogrammetric and Geodetic Map Revision forBoðazkale Archaeological Excavation Field

The aim of the project is to revise the mapof Boðazkale Archaeological ExcavationField by means of geodetic andphotogrammetric methods. According tothe plan which is prepared for takingphotographs; a preliminary study done atBoðazkale Archaeological Field. Controlpoints are painted on the rocks.

Photographs were taken by SMK 120stereo photogrammetric camera.Photographs are evaluated at Ý.T.Ü.Engineering Faculty PhotogrammetryLaboratory by means of B8S analyticalphotogrammetric instrument. A PC basedDigital photogrammetric software PICTRANwas used for evaluation.



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Camera calibration is made according tobundle adjustment and photographs thatwere taken without approximate values oforientation parameters, are scanned andoriented. Points are measured on orientedphotographs and point coordinates aredetermined by means at intersectedhomologous rays. According to theproject appropriateness, Digital TerrainModel (DTM) of Boðazkale ArchaeologicalField as obtained by the help of software,which is developed by thePhotogrammetry Division. Information,which was produced in Pictran software,is afterwards transferred into AUTOCADsystem.


In this study, it has beenobtained data forarchitechtural CAD drawingwith 1/20 and 1/50 scale bymeans of Digital CloseRange Photogrammetrictechniques at historical

Post Office of Galatasaraybuilding. Pictran D - Bsoftware were used forDigital PhotogrammetricSoftware evaluation. Rollei6008 Metric Camera wereused for taking photos withfocus 40 mm lens.

Architectural Photogrammetric Work AtHistorical Galatasaray Post Office



Terrestrial and Numerical Phot.-1

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