Primena tehnologije terestričkog laserskog skeniranja u geodeziji

This paper represents a relatively new terrestrial laser scanning technology and discusses its potential in the geodetic applications. In short, this work describes components of stationary laser scanning system, comparison to conventional terrestrial measuring techniques, mathematical model of scanning and the main sources of errors and accuracy of laser scanner.U radu se predstavlja relativno nova tehnologija terestričkog laserskog skeniranja i razmatraju njene mogućnosti u geodetskim oblastima primene. Ukratko su nabrojane komponente sistema za stacionarno lasersko skeniranje predstavljene specifičnosti u odnosu na konvencionalne terestričke merne tehnike, prikazan matematički model skeniranja i nabrojani glavni izvori grešaka i tačnost terestričkih laserskih skenera

Heritage protection as politics of memory

Baština je politički pojam čije značenje oblikuju institucije države-nacije i akademije. Država-nacija svoj legitimitet temelji na predodžbi kolektivne povijesnosti, pri čemu baština služi kao mjesto sjećanja koje povezuje takav narativ. Spomenuti se proces realizira kroz političke tj. državne institucije u vidu institucija koje se bave zaštitom baštine, obrazovnih institucija, muzeje i slično, te akademskih institucija struka vezanih uz zaštitu baštine, poput povijesti umjetnosti te etnologije i kulturne antropologije. Na nadnacionalnom planu proces se odvija putem međunarodnih institucija posvećenih zaštiti baštine kao što je UNESCO. Ovaj rad proučava i daje osnovni pregled mehanizama kroz koje se konstruiraju baštinski narativi i analizu nacionalnih i međunarodnih institucija kroz koje se taj mehanizam odvijaHeritage is a political concept whose meaning is formed by institutions of the nation-state and academia. The nation-state bases its legitimacy on the concept of collective history, where heritage serves as a place of memory that connects such a narrative. The aforementioned process is realized through political, i.e. state institutions in the form of institutions dealing with the protection of heritage, educational institutions, museums and the like, as well as academic institutions of professions related to the protection of heritage such as art history, ethnology and cultural anthropology. At the transnational level, the process takes place through international institutions dedicated to heritage protection such as UNESCO. This paper explores and provides a basic overview of mechanisms by which heritage narratives are constructed and provides analysis of national and international institutions through which this mechanism takes place

Accuracy of the objects modelling using terrestrial laser scanning technology

Skorašnja unapređenja performansi sistema terestričkog laserskog skeniranja (TLS) i trend opadanja cene ukazuju na značajan potencijal ove tehnologije i u zahtevnim inženjerskim zadacima. Pored činjenice da pojedini TLS poseduju frekvenciju skeniranja i preko 1.000.000 Hz, aspekt tačnosti ove metode geodetskog merenja igra presudnu ulogu u inženjerstvu. Postizanje adekvatne tačnosti modeliranja objekata tehnologijom TLS se osigurava projektovanjem geodetskog eksperimenta. To podrazumeva optimizaciju relevantnih parametara merenja i metodologije obrade podataka, kroz analizu uticaja različitih izvora grešaka u procesu merenja, instrumentalne preciznosti i performansi TLS, sagledavanja prostorne konfiguracije objekta i analize grešaka modela registracije i georeferenciranja. U radu su date osnove tehnologije TLS, matematički modeli opažanja, registracije i georeferenciranja. Predstavljeni su i analizirani različiti izvori grešaka merenja TLS koje potiču od instrumenta, sredine, objekta skeniranja i metodologije registracije i georeferenciranja. Predstavljena su trenutna dostignuća i ograničenja kalibracije TLS. Date su osnovne postavke 3D modeliranja oblaka tačaka tehnikama MNK uklapanja površi i zapreminskog modeliranja. Predložena je pojednostavljena procedura ispitivanja TLS po kriterijumima standarda ISO17123. Ona obuhvata ispitivanje, analizu i ocenu tačnosti TLS u laboratorijskim uslovima, po ugledu na postupke kalibracije sistema i mreže skenerskih signala. Metrološka laboratorija Građevinskog fakulteta u Beogradu je prilagođena za postupke ispitivanja TLS i izvršeno je ispitivanje jednog modela TLS. Najvažniji rezultati disertacije odnose se na: formiranje proširenog stohastičkog modela direktnog georeferenciranja, ustanovljavanje metodologije projektovanja merenja TLS na inženjerskim objektima i metodologiju indirektnog georeferenciranja linijskih objekata. Modifikovan je kompletan teorijski model grešaka direktnog georeferenciranja, korišćenjem procedure poznate stanice i orijentacije, i to u formi kovarijacione matrice vi koordinata tačaka. Ona sadrži sve relevantne uticaje, i to: deklarisanu preciznost rezultata TLS merenja, uticaje datih veličina kontrolne geodetske mreže, greške centrisanja, horizontiranja i merenja visine TLS i greške centrisanja i viziranja signala. Model je formiran na osnovu uticaja pojedinačnih izvora grešaka na vektor translacije i rotacije sistema oko z-ose...In high-demanding engineering applications, the latest performance improvements of the terrestrial lasers scanning (TLS) system and price decreasing trend shows the significant potential of this technology. Beside the fact that some scanners have the scanning frequency of over 1.000.000 Hz, in the engineering applications the accuracy of this survey method plays the key role. Achievement of the satisfactory accuracy of the object modelling using TLS has to be done by experiment designing. This implies the optimization process of the relevant measurements parameters and of the methodology of measurement processing through analysis of the different sources of measurement errors, instrumental precision and performance of the specific TLS, spatial configuration of the object and analysis of the models of registration and georeferencing errors. This work presents the fundamentals of TLS technology, mathematical models of measurements, registration and georeferencing. The different types of errors and their influences on the measurement quality are presented and analyzed. The sources of these errors are discussed in detail and treated as instrumental, environmental, object related and registration and georeferencing methodology dependent. The present TLS calibration achievements and existing operational limits are also analyzed. The basics of the point cloud 3D modelling techniques based on the least square fitting and volumetric approaches are given. The simplified test procedure of the TLS accuracy investigation in accordance with the ISO17123 standard is proposed. The proposed procedure covers investigation, analysis and accuracy estimation of the TLS system in laboratory conditions. This procedure is developed based on the model of the system calibration and the network design procedures. Metrological laboratory of the Faculty of Civil Engineering in Belgrade is customized for TLS testing. The accuracy investigation of a commercial TLS has been performed..

Еталонирање терестричких ласерских скенера у лабораторијским условима

Терестричко ласерско скенирање (ТЛС) представља методу брзог прикупљања велике количине података у виду „облака тачака“ који нам касније представља основу за приказивање реалног стања „објекта“ у виду тродимензионалног модела и вршење разних анализа над њим. Перманентни развој технологије, хардвера и софтвера у претходних 10-ак година је у великој мери утицао на експанизију методе ТЛС-а, и на квалитет података који добијамо као резултат њене примене. Методу ТЛС-а можемо декларисати као једну од „најмлађих“ метода која се користи у геодезији, грађевинарству, архитектури, просторном планнирању и др. Међутим, методи ТЛС-а недостају јасно дефинисане и стандардизоване теренске процедуре као и методе испитивања и еталонирања инструмената и прибора који се користи. Такође, још увек не постоји међународни стандард који би унифицирао декларисање карактеристика инструмената од стране произвођача. У овом раду је дат преглед свих процеса и прорачуна у циљу успостављања метролошког полигона за потребе еталонирања терестричко ласерских скенера. Приказана је и анализа података прикупљених приликом еталонирања три модела терестричко ласерских скенера

The possibilities of application of 3D digital models in cultural heritage objects' protection and revitalisation

Contemporary cultural heritage protection relies on precise technical documentation obtained by new technology accomplishments in the domain of 3D digital models. Both 3D models of the existing state of object and virtual ones are equally important in reconstruction and renewal processes. Accurate, textured and detailed 3D point cloud models of various objects, i.e. cultural heritage monuments, are outcomes of contemporary photogrammetric and laser scanning methods, aided by adequate software solutions. The authors presented procedures and results of terrestrial laser scanning and 3D modelling of a cultural heritage monument the monastery church of the complex Kastaljan, located in the mountain region Kosmaj in Serbia. The first part of presented research, concerning data acquisition, carried out using laser scanner and adequate software processing, resulted in 3D dense point cloud model and further 2D plan view along with characteristic cross sections. The possibilities of 3D model presentation, measurements and additional graphic operations were explored, through various software solutions aided by adequate technical support. The second part of research elaborated on the reconstruction of the entire 3D model of the church in the complex Kastaljan, dated back to the 13th century, according to its architectural style characteristics

Lesion Focused Super-Resolution

Super-resolution (SR) for image enhancement has great importance in medical image applications. Broadly speaking, there are two types of SR, one requires multiple low resolution (LR) images from different views of the same object to be reconstructed to the high resolution (HR) output, and the other one relies on the learning from a large amount of training datasets, i.e., LR-HR pairs. In real clinical environment, acquiring images from multi-views is expensive and sometimes infeasible. In this paper, we present a novel Generative Adversarial Networks (GAN) based learning framework to achieve SR from its LR version. By performing simulation based studies on the Multimodal Brain Tumor Segmentation Challenge (BraTS) datasets, we demonstrate the efficacy of our method in application of brain tumor MRI enhancement. Compared to bilinear interpolation and other state-of-the-art SR methods, our model is lesion focused, which is not only resulted in better perceptual image quality without blurring, but also more efficient and directly benefit for the following clinical tasks, e.g., lesion detection and abnormality enhancement. Therefore, we can envisage the application of our SR method to boost image spatial resolution while maintaining crucial diagnostic information for further clinical tasks.Comment: 4 pages, 2 figures, 1 table, Accepted as Oral Presentation by the SPIE Medical Imaging Conference 201

Analiza metoda georeferenciranja podataka terestričkog laserskog skeniranja

From the point of engineering geodesy this paper discuses registration and georeferencing methods of the terrestrial laser scanning (TLS) data. The different functional and stochastic spatial transformation models of the registration and georeferencing are presented and different sources of the errors are analyzed. Advantages and disadvantages of the various approaches are analyzed and recommendations for improving the precision of georeferencing are given.U radu se razmatraju modeli registracije i georeferenciranja oblaka tačaka prikupljenog tehnologijom terestričkog laserskog skeniranja (TLS), imajući u vidu njegovu primenu u inženjersko-tehničkim oblastima. Predstavljeni su različiti pristupi georeferenciranju preko funkcionalnih i stohastičkih modela prostorne transformacije i analizirani su uticaji različitih izvora grešaka. Razmatrane su prednosti i nedostaci različitih pristupa i date su preporuke za poboljšanje preciznosti georeferenciranja oblaka tačaka tehnologijom TLS. PR Projekat Ministarstva nauke Republike Srbije, br. TR36009: Primena GNSS i LIDAR tehnologije u monitoringu stabilnosti infrastrukturnih objekata i terena"