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Title:Interaktivna tvorba in prikaz obsežnih področij geometrijsko raznolikih dreves : doktorska disertacija
Authors:Kohek, Štefan (Author)
Strnad, Damjan (Mentor) More about this mentor... New window
Files:.pdf DOK_Kohek_Stefan_2019.pdf (23,68 MB)
 
Language:Slovenian
Work type:Doctoral dissertation (mb31)
Typology:2.08 - Doctoral Dissertation
Organization:FERI - Faculty of Electrical Engineering and Computer Science
Abstract:V doktorski disertaciji predstavimo nov pristop za upodabljanje obsežnejših področij geometrijsko raznolikih dreves. Najprej predstavimo nov pristop za tvorbo geometrijskih modelov dreves, ki deluje s simulacijo toka delcev v smeri od listja proti deblu in tako omogoča določitev oblike drevesa na podlagi ovojnice krošnje. V nadaljevanju predlagamo vzporedno implementacijo za grafične procesne enote, ki omogoča interaktivno tvorbo geometrijsko raznolikih dreves med samim upodabljanjem brez opaznih zakasnitev. Večje število dreves prikažemo z interaktivno hitrostjo tako, da bližnja drevesa prikažemo v višjem nivoju podrobnosti in oddaljena v nižjem nivoju podrobnosti brez potrebe po obdelavi že ustvarjenih geometrijskih podatkov. Ker pri upodabljanju obsežnih gozdnih področij z geometrijskim pristopom ne moremo tvoriti vseh dreves naenkrat, v nadaljevanju disertacije predlagamo še nov pristop za volumetrično upodabljanje krošenj najbolj oddaljenih dreves znotraj grafičnega cevovoda. Predlagani pristop tvori listje implicitno med delovanjem algoritma metanja žarkov na grafični procesni enoti in ne zahteva tvorbe geometrijskih podatkov vnaprej. Tudi pri tem pristopu izhajamo iz opisa ovojnice krošnje, s čimer dosežemo enak videz krošenj kot v primeru tvorbe geometrijskih podatkov dreves. V nadaljevanju oba pristopa združimo v celovit pristop za interaktivno sprotno tvorbo in upodabljanje večjega števila dreves med sprehodom po sceni. V eksperimentalnem delu doktorske disertacije ovrednotimo hitrost tvorbe in upodabljanja dreves, s čimer demonstriramo primernost predlaganega pristopa za interaktivno upodabljanje večjega števila dreves. Na trenutno dostopni strojni opremi lahko tvorimo drevesa, sestavljena iz več kot 400.000 členkov, v manj kot 25 ms, kar omogoča sprotno tvorbo večjega števila dreves med upodabljanjem. S tem ko tvorimo drevesa neposredno v želenem nivoju podrobnosti, oddaljena drevesa ustvarimo in prikažemo v krajšem času. Na koncu še pokažemo, da je volumetrično upodabljanje krošenj oddaljenih dreves brez vmesne tvorbe geometrijskih podatkov hitrejše kot na podlagi vnaprej pripravljenih geometrijskih podatkov.
Keywords:algoritmi, modeliranje in simulacija, tvorba dreves, simulacija toka delcev, GPU, GPGPU, paralelno računanje, nivo podrobnosti, volumetrično upodabljanje, grafični cevovod, algoritem metanja žarkov
Year of publishing:2019
Place of performance:Maribor
Publisher:[Š. Kohek]
Number of pages:VIII, 105 str.
Source:Maribor
UDC:004.92(043.3)
COBISS_ID:22497046 Link is opened in a new window
NUK URN:URN:SI:UM:DK:0AYTXOPO
License:CC BY-NC-ND 4.0
This work is available under this license: Creative Commons Attribution Non-Commercial No Derivatives 4.0 International
Views:178
Downloads:23
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Categories:KTFMB - FERI
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Secondary language

Language:English
Title:Interactive synthesis and visualization of vast areas with geometrically diverse trees
Abstract:This thesis proposes a new approach for large-scale forest visualization with geometrically diverse trees. First, we propose a new approach for tree geometry synthesis that is based on particle flow simulation. The simulation constructs the trees in the direction from the leaves towards the trunk. Therefore, the final tree structure is defined by a tree crown envelope. This approach is later adapted for tree synthesis on graphics processing units to enable interactive tree geometry synthesis of diverse trees during visualization without noticeable delays. To visualize a larger number of trees, the nearest trees are generated at a higher level of detail, while the distant ones are generated directly at a lower level of detail, without the need for post-processing of existing geometric data. However, all the trees cannot be synthesized simultaneously, therefore, we propose a new approach for volumetric tree crown visualization of distant trees within the graphics pipeline. The proposed approach generates the leaves implicitly during a ray casting algorithm on a graphics processing unit, without requirements for intermediate geometric representation. This approach also considers the tree crown envelope representation, and, thus, enables achieving the same tree crown appearance in respect to the tree crown based on geometric representation. In the continuation, both approaches are combined within a new comprehensive framework for interactive on-the-fly generation and visualization of large-scale forests, while navigating through the scene. In the results, tree synthesis and visualization speed are evaluated, and the suitability of the proposed approach is demonstrated for interactive large scale forest visualization. Currently available hardware allows generating trees consisting of 400,000 internodes in less than 25 ms, which enables generating larger numbers of trees between individual frames. Additionally, generating trees directly at a specific level of detail allows faster generation and visualization of the trees at the lower level of detail. Finally, we demonstrate that the procedural volumetric tree crown visualization of distant trees achieves higher rendering rates in relation to the visualization based on existing geometric representation.
Keywords:algorithms, modeling and simulation, generation of trees, particle flow simulation, GPU, GPGPU, parallel computing, level of detail, volumetric rendering, graphics pipeline, ray casting algorithm


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