3D digitization of texture-less surfaces using close-range photogrammetry

Kreiranje 3D modela i njihova vizuelizacija postali su sastavni deo procesa razvoja novih ili redizajniranja postojećih proizvoda. U ovom istraživanju pažnja je posvećena rešavanju problema 3D digitalizacije kod blisko-predmetne fotogrametrije zasnovane na određivanju strukture iz kretanja, na površima bez karakterističnih obeležja primenom projektovanja sintetički generisanih slika u vidu svetlosnih tekstura. Akcenat je stavljen na generisanje novih sintetičkih slika koje imaju izraženu vizuelnu teksturu, njihovu evaluaciju i primenu na objektima sa monotonim vizuelnim površima sa ciljem podizanja ukupne tačnosti rekonstruisanih 3D modela. Verifikacija primene sintetičkih slika i njihovih svetlosnih tekstura sa aspekta geometrijske i dimenzione tačnosti je realizovana primenom računarom podržane inspekcije (CAD inspekcije).The creation of 3D models and their visualization have become an integral part of the process of developing new or redesigning existing products. In this research, attention was paid to solving the problem of 3D digitization in close-range photogrammetry based on the structure from motion on surfaces without characteristic features by designing synthetically generated images in the form of light textures. An accent is placed on the generation of new synthetic images that have a pronounced visual texture, their evaluation, and application on objects with monotonous visual surfaces with the aim of raising the overall accuracy of reconstructed 3D models. The verification of the application of synthetic images and their light textures from the aspect of geometric and dimensional accuracy was realized through the use of computer-aided inspection (CAI inspection)

3D digitization of texture-less surfaces using close-range photogrammetry

Kreiranje 3D modela i njihova vizuelizacija postali su sastavni deo procesa razvoja novih ili redizajniranja postojećih proizvoda. U ovom istraživanju pažnja je posvećena rešavanju problema 3D digitalizacije kod blisko-predmetne fotogrametrije zasnovane na određivanju strukture iz kretanja, na površima bez karakterističnih obeležja primenom projektovanja sintetički generisanih slika u vidu svetlosnih tekstura. Akcenat je stavljen na generisanje novih sintetičkih slika koje imaju izraženu vizuelnu teksturu, njihovu evaluaciju i primenu na objektima sa monotonim vizuelnim površima sa ciljem podizanja ukupne tačnosti rekonstruisanih 3D modela. Verifikacija primene sintetičkih slika i njihovih svetlosnih tekstura sa aspekta geometrijske i dimenzione tačnosti je realizovana primenom računarom podržane inspekcije (CAD inspekcije).The creation of 3D models and their visualization have become an integral part of the process of developing new or redesigning existing products. In this research, attention was paid to solving the problem of 3D digitization in close-range photogrammetry based on the structure from motion on surfaces without characteristic features by designing synthetically generated images in the form of light textures. An accent is placed on the generation of new synthetic images that have a pronounced visual texture, their evaluation, and application on objects with monotonous visual surfaces with the aim of raising the overall accuracy of reconstructed 3D models. The verification of the application of synthetic images and their light textures from the aspect of geometric and dimensional accuracy was realized through the use of computer-aided inspection (CAI inspection)

Primena CAD/CAM tehnologije u projektovanju i izradi mostova pune anatomske forme na bazi cirkonijum-dioksida

Daily progress of dentistry, especially in the field of prosthodontics is introducing new materials and technologies. With the increasing need for aesthetically acceptable and non-metal materials, it came to development and improvement of ceramic materials and computer based systems (CA). The patient came in order to compensate the missing left lateral incisor. Since the adjacent teeth are brushed and the print was taken, casted model has been scanned using 3Shape D800 laboratory scanner. Dental restoration has been designed using 3Shape DentalSystem Premium software and the available tools. After completing the virtual design, the data are sent to the program responsible for CAM Zenotec® mini CAD/CAM device. As a result, the compensation with the full morphology was obtained without the need for finishing works.Stomatologija, posebno stomatološka protetika svakodnevno napreduje uvođenjem novih materijala i tehnologija. Kako se javlja sve veća potreba za estetski prihvatljivim i bezmetalnim materijalima, došlo je do razvoja i unapređenja keramičkih materijala i računarima podržanih sistema (CA). Pacijent se javio radi nadoknade nedostajućeg levog bočnog sekutića. Pošto su susedni zubi zbrušeni i uzet otisak, izliven je model koji je skeniran pomoću 3Shape D 800 laboratorijskog skenera. Zubna nadoknada je dizajnirana pomo ću 3Shape DentalSystem Premium softvera korišćenjem raspoloživih alata. Nakon završenog dizajna virtuelni podaci su poslati u program odgovoran za CAM Zenotec® mini CAD/CAM uređaja. Kao rezultat, dobijena je nadoknada pune morfologije bez potrebe za dorađivanjem

Copyright Protection of 3D Digitized Sculptures by Use of Haptic Device for Adding Local-Imperceptible Bumps

This research aims to improve some approaches for protecting digitized 3D models of cultural heritage objects such as the approach shown in the authors\u27 previous research on this topic. This technique can be used to protect works of art such as 3D models of sculptures, pottery, and 3D digital characters for animated film and gaming. It can also be used to preserve architectural heritage. In the research presented here adding protection to the scanned 3D model of the original sculpture was achieved using the digital sculpting technique with a haptic device. The original 3D model and the model with added protection were after that printed at the 3D printer, and then such 3D printed models were scanned. In order to measure the thickness of added protection, the original 3D model and the model with added protection were compared. Also, two scanned models of the printed sculptures were compared to define the amount of added material. The thickness of the added protection is up to 2 mm, whereas the highest difference detected between a matching scan of the original sculpture (or protected 3D model) and a scan of its printed version (or scan of the protected printed version) is about 1 mm

Uloga statističkih evaluatora i njihova primena kod analize tačnosti segmentiranih medicinskih snimaka

Neosporna je uloga i primena medicinskih snimaka u današnjoj oblasti medicine i stomatologije jer je na osnovu njih moguće izvršiti tačnu dijagnozu kod pacijenata. Međutim, primenom savremenih uređaja za akviziciju ovih snimaka, mogu se pojaviti određene anomalije u vidu artefakata na medicinskim simcima. Uporedo sa ovim problemom, razvijale su se i metode za obradu medicinskih snimaka. Kako bi se verifikovala njihova primena i dokazala uspešnost njihove primene, tako su se razvijale i mnoge metode i evaluatori za analizu i statističku obradu ovih snimaka. U ovom radu biće prikazane neke od najčešće primenjivanih statističkih metoda i evaluatora koji se koriste kod analize medicinskih snimaka

Pregled stanja i analiza najčešće primenjivanih metoda za segmentaciju slike

Uopšteno govoreći, segmentacija predstavlja postupak klasifikacije objekata od interesa i njihove ekstrakcije od pozadine, a kao postupak predstavlja neizostavan korak kod obrade slike. U okviru ovog rada biće predstavljena podela i pregled najčešće primenjivanih metoda za segmentaciju slike. Na osnovu literaturnih izvora izvršena je klasifikacija metoda u odnosu na njihov mehanizam sa kratkim opisom osnovih podela i analizom najčešće primenjivanih metoda

Pregled stanja i analiza najčešće primenjivanih metoda za segmentaciju slike

Uopšteno govoreći, segmentacija predstavlja postupak klasifikacije objekata od interesa i njihove ekstrakcije od pozadine, a kao postupak predstavlja neizostavan korak kod obrade slike. U okviru ovog rada biće predstavljena podela i pregled najčešće primenjivanih metoda za segmentaciju slike. Na osnovu literaturnih izvora izvršena je klasifikacija metoda u odnosu na njihov mehanizam sa kratkim opisom osnovih podela i analizom najčešće primenjivanih metoda

3D DIGITIZATION OF FEATURELESS DENTAL MODELS USING CLOSE RANGE PHOTOGRAMMETRY AIDED BY NOISE BASED PATTERNS

Development and improvement of 3D digitizing systems provide for the ability to digitize a growing number of materials and geometrical forms of greater complexity. This paper presents the application of 3D digitizing system using close range photogrammetry on the upper jaw cast in plaster in order to obtain its 3D model. Because of the low visual characteristics of gypsum, such as color and texture, many questions arise about the possibility of applying this particular method to this type of physical models. In order to overcome bad visual properties of gypsum, this paper analyzes the possibility of the photogrammetry method application supported by the projected light texture which is based on patterns in the form of noise-obtained  mathematically modeled functions. In order to determine the selected image for light texture which gives the better results, an experiment was designed and carried out. Only two images were tested. One image is selected based on previous research and the other one was generated by the Matlab function for uniformly distributed random numbers. For validation and a comparative analysis of the results, an object of 3D digitization was generated with and without projected light texture. CAD inspection was applied for the analysis of the obtained 3D digitizing results. 3D model obtained by approved professional optical 3D scanner as a reference was used. The results in this paper confirm better accuracy of 3D models obtained with the use of light textures, but this approach requires additional hardware and setup adjustment for images acquisition

Reconstruction of 3D models of cast sculptures using close-range photogrammetry

This paper presents the possibilities of application of close-range photogrammetry, based on the Structure-from- Motion (SfM) approach, in 3D model’s reconstruction of bronze cast sculptures. Special attention was dedicated to the analysis of image processing strategy, and its impact on the 3D model reconstruction quality. For the purpose of analysis a bust of Nikola Tesla, placed in front of the Faculty of Technical Sciences University of Novi Sad was used. Experimental results indicate that the strategy employing multi-group photo processing provides substantial reductions in processing time while providing satisfactory results in 3D reconstruction

Modelling of micro-turning process based on constant cutting force

In this research, an evaluation of the external transverse micro-turning with conventional cutting inserts was performed with a constant cutting force in a dry environment. During machining, the number of revolutions, machining time and cutting forces was varied. Before and after machining, the diameter of the workpiece, circularity and the roughness of the machined surface was measured. The obtained results indicate that with increasing number of revolutions, time and cutting force, the cutting depth increases. The results show that this type of machining can achieve very small cutting depths and reduce circularity deviation and roughness of the machined surface. Based on the experimental results, the modelling of the artificial neural network (ANN) was performed which reliably predicted the change in diameter, cylindricity, and roughness after micro-turning operation, with a mean percentage error smaller than 3 %. It can be concluded that the application of ANN is adequate during the machining process with the constant cutting force, since the output parameters can be predicted with small error, while also reducing effort and costs