Final Report: Photogrammetry
Final Report:photogrammetryDigital 3D photogrammetry modellingof selected artefacts fromthe collection of theMuseum of ByzantineCulture, Thessaloniki,Greece.A project by:Yiğit Zafer Helvacı - 2016recipient of the ElizabethBartman Museum InternshipScholarshipYigit Z. Helvaci final reportThis final report aims todocument the purpose, scopeand goals of a low budgetproject that has been developedand undertaken to create digital3D models of a selection ofobjects from the collection of theMuseum of Byzantine Culture,Thessaloniki. The models werecreated using photogrammetrythat has proven to be an efficient,user - friendly and low budgetdocumentation technique, easilyapplicable to archaeology andcultural heritage. The projectwork has been divided into twomain sections: a) data collection(taking photographs) in themuseum environment) b) dataprocessing and model building.At the end of the museum worksection of the project, 35artefacts have beenphotographed and will bedigitally modelled in theupcoming months. The projecthas been made possible by thefinancial support of theArchaeological Institute ofAmerica and cooperation of theMuseum of Byzantine Culture,Thessaloniki.Page 1
THE PROJECTPhotogrammetry TechniqueThe Photogrammetry technique can be defined as the science, art andtechnology of obtaining accurate information about physical objects andthe environment through the processes of recording, measuring andi n t e r p re t i n g p h o t o g ra p h y i m a g e s . Th e b a s i c p r i n c i p l e o fphotogrammetry mimics the natural ability of human depth perception.The ability of three dimensional vision is a result of the offset inperspective centers between the left and right eyes. Digital imagescreated to simulate this perspective shift are referred to as stereoscopicor stereo. The succession of stereoscopic images taken from consecutivepositions with an overlap about 60% are subsequently processedthrough computer software to create 3D images. Compared to othertechniques such as laser scanning, photogrammetry is affordable andrelatively user-friendly and can be applied to many physical objects suchas archaeological artefacts, buildings and topographical features of anarea.Museum of Byzantine Culture, Thessaloniki, Greece:Founded in 1994, the museum is currently one of the most importantcultural entities of the city of Thessaloniki. The monastic architecturaldesign of the museum is a homage to the city s Byzantine past. Themuseum houses a remarkably diverse collection that can illustrate thereligion, culture and daily life of the period.OBJECTIVESThe main aim of this project has been the construction of digital 3Dmodels of the artefacts from the collection of the Museum of ByzantineCulture, Thessaloniki, Greece. Once complete and made available to themuseum, these models can be shared online (the museum s officialwebsite or a dedicated “sketchup” profile) with the public. Furthermore,photogrammetry has proven to be an effective tool for documentingarchaeological objects and structures as well as museum collections.Therefore it is hoped that this (relatively) small collection of 3D modelswill be a valuable tool for the museum staff such as conservators andresearchers who will be able to visually inspect the modelled objectsthrough different angles and lighting conditions.Through this internship my personal aims have been to:— Develop and execute a research project independently,— Gain practical and professional experience in a museum environment,— Transform the theoretical training I received in photogrammetry intopractice and develop skills for Ph.D. level studies.— Establish professional contacts in the cultural heritage field in Greece.Yigit Z. Helvaci final reportPage 2
TIMEFRAME 6 August: funds received,6 August - 22 August: equipment purchases and preparation,22 August - 20 September: internship - data collection at the museum,20 September onwards - data processing - model building,Notes:Because of budget limitations, the time spent at the museumenvironment had to be limited to a duration of 4 weeks. One of thereasons for this has been the fact that this project was designedconsidering a larger budget (aproximately 3000 Eur) but eventually hadto be scaled-down.While the budget provided by AIA has run out at the end of the firstmonth, my dedication to the project remains solid and I will continue towork on the models to bring this internship project to a completion. Incompliance with the museum s request, I will be giving the ready modelsto the museum management who will publish them on the officialmuseum website. On the other hand, should the AIA community wishesto see the models before the museum s publishing process is complete,I can provide access to the models.METHODOLOGY:To create the models, the following work-flow has been created.Lighting:Visible light. 3 units of 50 x 70 cm soft box for continuous lighting. Eachunit holds 5 energy saving lightbulbs with a total output of 2850W. Thelight temperature was 5500K to imitate day - light conditions.Photography:The objects were systematically photographed using the rules /guidelines recommended by Agisoft Photoscan Pro. software user smanual. The photographs overlapped by at least 60%. In the camera, theoutput format was selected as RAW that facilitated post processing ofthe images.File management:Once the files (photos) were acquired, they were systematicallytransferred to an external drive. Each museum object was allocated aseparate folder and the processed images were stacked in separatefolders according to their purpose / properties.Image post processing:Yigit Z. Helvaci final reportPage 3
Before the images fed into the photogrammetry processing software,they were edited in Adobe Photoshop. The process included: conversion of RAW files into JPEG, exposure and colour - balance corrections increasing the contrast and sharpness of the imagesThese corrections have been a somewhat necessary part of themodelling process for a variety of reasons. To elaborate, thephotogrammetry software cannot handle RAW files. The exposure andcolour balance corrections increase the texture quality of the models(accuracy and aesthetics) and increased contrast and sharpnesscontribute to the performance and output quality of thephotogrammetry software.Model BuildingThe models have been created by using Agisoft - Photo-Scan Pro.version 1.2.6. for Mac.In constructing the models, the general workflow imposed by thesoftware was as follows:Camera alignmentDense point cloudBuild meshBuild textureIn general the following quality - detail settings have been used:Camera alignment: medium or high depending on the amount ofphotographs.Dense point cloud: medium or highBuild mesh: always highest possible setting in order to capture thesurface topography of the objects as accurately as possible.Build texture: standardNote: Considering the average specifications of domestic or officecomputers, the models were not created in the highest available settingin order to facilitate handling.Yigit Z. Helvaci final reportPage 4
Computer specifications:Processor: 2 GHz Intel Core i7Memory: 8 GB 1600 MHz DDR3Graphics: Intel Iris Pro 1536 MBModel export:The created models were saved in the .psz format (photogammetrysoftware) and as .obj files (a more universal file format for 3D objects).Furthermore, the constructed models were uploaded in the sketchupwebsite. By the request of the museum, the uploaded models arepassword protected and currently not open for public viewing. Theaccess information of some of the ready models have been provided inthis report.Some exported models can be viewed through the following links:Gold bracelet: https://skfb.ly/SNIYMarble head: https://skfb.ly/TrnnMarble relief with Mother Mary: https://skfb.ly/SOCvSarcophagus with wall paintings: https://skfb.ly/TGPBpassword for all the models: selanikRESULTSDuring the museum internship period, I have been able to photographthirty five objects from the museum collection. These objects wereselected by the museum staff. The main criteria in selecting the objectswere their size and significance for the museum collection. Overall, theartefacts that have been photographed represent a diverse set ofobjects including, marble architectural elements, floor mosaics, goldjewellery, wall paintings, sarcophagi and wooden panels. A complete listof the photographed objects is as follows:Yigit Z. Helvaci final report1ΑΓ - 3171marble column (left)2AΓ - 3171marble column (right)3ΑΓ - 3170marble arch4AΓ - 3221marble pedestal5ΒΤ - 178 / 1 and BT 178 / 2sarcophagus with wall paintings6BT - 165sarcophagus with wall paintings7ΑΓ - 2491the good shepherd - table foot?8AΓ - 1808marble slab - decoration element9BT - 156B -1sarcophagus with wall paintings - the end wallPage 5
10BT - 156Bsarcophagus with wall paintings11BT - 156A -1sarcophagus with wall paintings - the end wall12BT - 156Asarcophagus with wall paintings13BT - 200apse with wall paintings14AΓ - 776marble slab - decoration element15AΓ - 267marble slab - decoration element16AΓ - 3130sandstone slab - decoration element17AΓ - 3151marble slab - decoration element18AΓ - 3152marble relief19AΓ - 275marble slab - decoration element20ΠΛ - 1marble slab21AΓ - 775round marble decoration element22BT - 126arch piece with wall painting fragments23BEI - 339wooden icon panel24BEI - 97wooden icon panel25BEI - 162 a - kstgilded church panel26AΓ 3004marble head27ΑΓ 774marble architectural element. stage.28ΑΓ 913decorated marble door frame29AΓ 4marble column head30AΓ 772marble relief31AΓ 275marble relief32mosaic floor33lead seal34BEI - 162 - detailwooden icon panel35BKO 262gold bracelet with enamel decorationAt this stage, I have been working on the processing of the raw data withvery good results. The modelling of three objects have been completeand approximately ten other models are in the “build mesh” stage.Because the construction of the models (and the the manipulation of thesoftware) requires a considerable level of trial and error, some modelscan take up to 3 days with my computer s specifications.Some illustrations to demonstrate the current stage of the modelling isas follows:Yigit Z. Helvaci final reportPage 6
BEI - 162 a - kstΒΤ - 178 / 1BEI - 162a - kstYigit Z. Helvaci final reportPage 7
AΓ 3004(finalised)BKO 262(finalised)BKO 262BT 200Yigit Z. Helvaci final reportPage 8
AΓ - 3152BEI 339Yigit Z. Helvaci final reportPage 9
AΓ - 3221I am also hoping that the availability of these models will be a valuabletool for the museum conservators and other researchers. When themodels are complete, the objects can be viewed from different anglesand under different lighting conditions. Furthermore, by removing thesurface image, the viewer can observe the surface topography which cancontribute to a better understanding of the object s conservation state.Furthermore the ability of manipulating the digitals models of the heavyobjects in the digital platform should provide accessibility for theresearchers.Yigit Z. Helvaci final reportPage 10
ACKNOWLEDGEMENTSFirst and foremost, I would like to extend my gratitude to theArchaeological Institute of America. Surely, without the support andfinancial help provided by the Elizabeth Bartman Museum InternshipScholarship, this project could not have taken place. In a more personalnote, the skills that I have developed through this internship project willbe valuable tools that I will cherish during my Ph.D. level studies in theupcoming year. To elaborate, this project has given me a subject andfocus, through which I could develop my skills in photogrammetry.Furthermore, in the aftermath of this project, I feel much more confidentabout independently designing and executing a research project andcannot wait to build another project from scratch.I would like to thank Ms. Samantha Craig with her endless support andhelp during the project. I would like to thank the Museum of ByzantineCulture, Thessaloniki and in particular to Evangelia Angelkou andMagdalena Muratidou for their generous help and hospitality during myinternship. Lastly, I would like to thank the museum photographer NikosTsiokas (www.fototopos.net) for his much valued feedback on myphotographs and models.Yigit Z. Helvaci final reportPage 11
photogrammetry mimics the natural ability of human depth perception. The ability of three dimensional vision is a result of the offset in perspective centers between the left and right eyes. Digital images created to simulate this perspective shift are referred to as stereoscopic or stereo. The succession of stereoscopic images taken from .
Photogrammetry is a cost efficient surveying method for mapping large areas. Photogrammetry may be safer than other surveying methods. It is safer to take photographs of a dangerous area than to place surveyors in harms way. Photogrammetry provides the ability to map areas inaccessible to field crews.
photogrammetry. He developed the analytical solutions to space resection, orientation, intersection, rectification, and control extension using direction cosines. Church, a professor at Syracuse University and one of the founding members of the American Society of Photogrammetry, is referred to as the "American Father of Photogrammetry".
Photogrammetry has been previously validated as an effective technology for documenting both damaged vehicles and scenes [1,2,3,4,5,6,7,8,9,10,11,12]. Modern photogrammetry uses the same photogrammetric principles, but requires less user input and delivers more data points in its solution. Photogrammetry software is capable
Unity Photogrammetry Workflow 3 1. Overview 1.1. Introduction What is photogrammetry? Photogrammetry is the process of authoring a digital asset using multiple photos of the original real-
White light scanner (point clouds) Photogrammetry solutions. 18 22/08/2017 Photogrammetry solutions Photogrammetry (Single points, Adapter, Features) . White-Light Scanner (Structured light) Very high accuracy (down to some µm) Highest resolution Scalable for different volumes (mm to several m)
4.1.4 Aerial Photogrammetry Aerial photogrammetry is the science of deducing the physical dimensions of objects on or above the surface of the Earth from measurements on aerial photographs of the objects. The end result produces the coordinate (X, Y, and Z) position of a particular point, a planimetric feature, and a graphic representation
Digital Photogrammetry The digital, or soft copy, photogrammetry systems (Figure 8) are much simpler in design than the analytical systems; they consist of a computer with a stereo-capable graphics system, 3-D glasses with electronic shutters, and a “3-D mouse” as a user interface. The 3-D mouse is a
In order to simplify understanding an abstract definition and to get a quick grasp at the complex field of photogrammetry, we adopt a systems approach. Fig. 1.3 illustrates the idea. In the first place, photogrammetry is considered a black box. The input is characterized by obtaining rel
