published_or_final_version / abstract / toc / Education / Master / Master of Science in Information Technology in Education

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

published_or_final_version / Zoology / Master / Master of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

A computer algorithm is developed for clipping and capping N-sided polyhedra with arbitrary planes. The algorithm is then expanded to include the processing of general two and three dimensional geometric finite element model data. Data processing is included for the transformation of original model results to match the clipped and capped graphical display model. The algorithms are implemented in a FORTRAN program that may be directly substituted into the MOVIE.BYU/ARIZONA graphics system. The new SECTION program maintains all the functions of the original version while incorporating several major new features. These new features include the expansion of the geometric library to two and three dimensional elements and two new general forms for polygons and polyhedra. Another significant change in the processing is the implementation of the reentrant clipping and capping routines. This feature permits a previously clipped model to be clipped again and again by new and different clipping planes. The above features as well as enhanced input data schemes including a preliminary interface to NASTRAN are offered as a skeleton for future modifications. The major routines in the program have taken advantage of dynamic memory allocation via FORTRAN subroutine argument calls. Through this latter feature new capability can be concatenated to the end of the current processing in a prototype manner for rapid implementation and exploration.

In recent decades, the popularity of freeform shapes in contemporary architecture poses new challenges to digital design. One of them is the process of rationalization, i.e. to make freeform skins or structures affordable to manufacture, which draws the most attention from geometry researchers. In this thesis, we aim to realize this process with simple geometric primitives, circular arcs. We investigate architectural surfaces and structures consisting of circular arcs. Our focus is lying on how to employ them nicely and repetitively in architectural design, in order to decrease the cost in manufacturing. Firstly, we study Darboux cyclides, which are algebraic surfaces of order ≤ 4. We provide a computational tool to identify all families of circles on a given cyclide based on the spherical model of M ̈obius geometry. Practical ways to design cyclide patches that pass through certain inputs are presented. In particular, certain triples of circle families on Darboux cyclides may be suitably arranged as 3-webs. We provide a complete classification of all possible 3-webs of circles on Darboux cyclides. We then investigate the circular arc snakes, which are smooth sequences of circu- lar arcs. We evolve the snakes such that their curvature, as a function of arc length, remains unchanged. The evolution of snakes is utilized to approximate given surfaces by circular arcs or to generated freeform shapes, and it is realized by a 2-step pro- cess. More interestingly, certain 6-arc snake with boundary constraints can produce a smooth self motion, which can be employed to build flexible structures. Another challenging topic is approximating smooth freeform skins with simple panels. We contribute to this problem area by approximating a negatively-curved 5 surface with a smooth union of rational bilinear patches. We provide a proof for vertex consistency of hyperbolic nets using the CAGD approach of the rational B ́ezier form. Moreover, we use Darboux transformations for the generation of smooth sur- faces composed of Darboux cyclide patches. In this way we not only eliminate the restriction to surfaces with negative Gaussian curvature, but, also obtain surfaces consisting of circular arcs.

Η παρούσα μελέτη πραγματοποιήθηκε στα πλαίσια της διπλωματικής εργασίας «Ψηφιακός Επεξεργαστής και Γραφικά Υπολογιστών». Κατά τη διάρκεια αυτής της μελέτης είχαμε την ευκαιρία να προσεγγίσουμε και να κατανοήσουμε την διαδικασία που επιτελείται για την αναπαράσταση γραφικών στην οθόνη του υπολογιστή μας, του κινητού μας τηλεφώνου και κατ’ επέκταση να προτείνουμε νέες ιδέες και τεχνικές οι οποίες αποσκοπούν στην βελτίωση και αύξηση της αποδοτικότητας. Για το λόγο αυτό μελετώντας τους υπάρχοντες αλγόριθμους, καταλήξαμε στην πρόταση ενός νέου ο οποίος προορίζεται κυρίως για συσκευές απεικόνισης μικρού μεγέθους όπως τα κινητά τηλέφωνα και έχει ως βασικό σκοπό τη μείωση σύνθετων υπολογιστικών πράξεων και εξοικονόμηση ενέργειας. Στη παρούσα εργασία παρουσιάζεται η λειτουργία των υπαρχόντων αλγόριθμων καθώς και του προτεινόμενου. Πραγματοποιούνται συγκρίσεις μεταξύ αυτών προκειμένου να δούμε το ποσοστό βελτίωσης που υπεισέρχεται, ενώ αναπτύσσουμε και το υπόβαθρο για την υλοποίηση και εφαρμογή του προτεινόμενου αλγόριθμου στην πράξη. / -

No description available.

The goal of this research is to develop new, interactive methods for creating very high genus 2-manifold meshes. The various approaches investigated in this research can be categorized into two groups -- interactive methods, where the user primarily controls the creation of the high-genus mesh, and automatic methods, where there is minimal user interaction and the program automatically creates the high-genus mesh. In the interactive category, two different methods have been developed. The first allows the creation of multi-segment, curved handles between two different faces, which can belong to the same mesh or to geometrically distinct meshes. The second method, which is referred to as ``rind modeling'', provides for easy creation of surfaces resembling peeled and punctured rinds. The automatic category also includes two different methods. The first one automates the process of creating generalized Sierpinski polyhedra, while the second one allows the creation of Menger sponge-type meshes. Efficient and robust algorithms for these approaches and user-friendly tools for these algorithms have been developed and implemented.

Nuo pat vaikystės, kai pirmą kartą paėmiau į rankas popieriaus lapą ir piešimo priemones, pajutau potraukį piešti gyvąją gamtą. Ypač mėgau įamžinti popieriuje gyvūnus, vabzdžius, augalus. Nuo pat mažens mane žavėjo jų įvairovė, spalvos, kūno formos, faktūros ir dar daugybė nuostabių dalykų, kuriais aš labai domėjausi. Juos parsinešdavau į namus, stebėdavau ir mėgindavau nupiešti - norėdavosi įamžinti juos popieriaus lape. Vėliau ėmiau perpiešinėti įvairių gyvūnų,vabzdžių bei augalų nuotraukas iš knygų, enciklopedijų . Taip tobulinau piešimo įgūdžius. Savo bakalauro darbui atlikti pasirinkau piešimo discipliną. Piešimas –tai priemonė kurti vaizdą, naudojant bet kuriuos būdus, technikas bei technologijas. Jis paprastai susijęs su ženklais ant paviršiaus, taikant įspaudimo priemonę. Pagrindinės piešimo priemonės: grafitinis pieštukas, plunksna, rašalas, teptukai, vaškas, spalvoti pieštukai, pastelės, anglis, sangvinas. Skaitmeniniai įrenginiai, kurie imituoja šių priemonių poveikį, irgi plačiai naudojami. 1 Bakalauro darbą sudaro trijų darbų ciklas, pavadinimu „Išlikimas“. Darbams atlikti pasirinkau mišrią techniką – piešimą, bei kompiuterinę grafiką. Kuriant daugiasluoksnes kompozicijas naudojau „Adobe Photoshop CS3“ programą. Savo baigiamajame darbe „Išlikimas“ pasirinktą temą stengiausi interpretuoti savaip. Tai realių, kruopščiai ir tiksliai nupieštų formų ir abstrakčių vaizdų mišinys, kuriuo siekiau atskleisti savo požiūrį į meninę kūrybą. Diplominio darbo teorinėje dalyje... [toliau žr. visą tekstą] / I had an appeal to drawing living nature since my early childhood when I touched a sheet of paper and drawing tools for the first time. I especially liked memorializing animals, insects, plants on paper. Since the early childhood I was fascinated by their variety, colours, body shapes, facture and many other things that had drawn my interest towards them. I used to take lots of them home, I used to observe them and I tried to draw them – I wanted to memorialize them on a sheet of paper. Later I used to copy photographs with animals, insects, and plants form various books, encyclopaedias. This is the way how I improved my drawing skills. I have chosen the subject of drawing for my diploma work. Drawing is a means for creating a picture by using any means and technologies. It is usually related to signs and using a pressure tool on the surface. Major tools: a lead pencil, a nib, ink, paint-brushes, wax, coloured pencils, pastels. Digital devices1 imitating the effect of these tools were often used as well. The diploma work consists of a collection of three works named as “Išlikimas” (“Survival”). I have chosen a mixed technique for doing the pieces of creation – drawing and computer graphics. I used “Adobe Photoshop CS3” program for creating multilayer compositions. I tried to interpret the selected subject in my own manner in my final work “Išlikimas” (“Survival”). It is a mix of realistic, thoroughly drawn shapes and abstract images by means of which I sought to show my... [to full text]