A two-part paleolimnological study was conducted to: i) understand the important factors that are related to the present-day distribution of scaled-chrysophytes; ii) investigate changes in the scaled-chrysophyte assemblages in the Experimental Lakes Area northwestern Ontario, in response to recent climate warming. Scaled-chrysophyte assemblages were analyzed in the modern sediments of 40 ELA lakes to determine their relationship to measured environmental variables. The sediment record from 210Pb dated cores from six ELA lakes were analyzed at a sub-decadal resolution to evaluate if chrysophytes were changing in a consistent fashion and if these changes could be accounted for by measured climatic factors. Ordination analysis of the modern chrysophyte flora was significantly related to pH, lake depth, and the degree of thermal stratification, as well as water temperature. Mallomonas punctifera ‘small’ and Mallomonas acaroides were indicators of warm surface-waters. High-resolution analysis of six ELA lakes revealed pronounced shifts in the chrysophyte assemblages over the last ca. 150 years. The most notable shift in the chrysophyte assemblage was characterized by an overall shift towards higher relative abundances of colonial taxa. In several lakes increases in unicellular warm-water taxa were also observed. Breakpoint Analysis identified significant changes in the chrysophyte assemblages beginning in the late-1800s to mid-1900s in most lakes. An interclass correlation coefficient (ri) was used to assess the temporal coherency of the chrysophyte assemblages over the past ca. 100 years. All lakes displayed a similar directional change which was significantly coherent (p<0.05). A Brien’s Test identified sub-sets of lakes that were temporally coherent and homogenous. The high coherency of two groups, (Group A, grand mean=0.89, p-value=5.3x10-15; Group B, grand mean=0.38, p-value=0.038), suggests the dominance in extrinsic factors in governing the lake responses. The average PCA axis-1 scores of Group A (r-value=0.62, p=0.03) and Group B (r-value=0.60, p=0.038) were significantly correlated to regional mean annual temperature. Collectively, the results of this study suggest that changes observed in the scaled-chrysophyte assemblages in the ELA region are consistent with recent climate warming. / Thesis (Master, Biology) -- Queen's University, 2011-09-29 16:42:06.753

Background. Draw calls in interactive applications are often recorded on a per-frame basis, despite already residing in memory after recording in the previous one. At the same time, scenes tend to be structurally stable; what exists during one frame is likely to exist in the next ones as well. Objectives. By exploiting the observed temporal coherence in scene structures, this thesis aims to devise a solution to record draw calls incrementally. The purpose of such recording is to reuse what has been recorded previously instead of recording it anew. Two approaches to incremental recording are implemented and compared to regular naïve recording in terms of overhead time. One of them makes use of an extension to the Vulkan graphics application programming interface (API) to evaluate indirect pipeline changes. Methods. A simulation is used as the method of evaluation, using a simple scene where triangles are rendered in individual draw calls. Two sizes of the scene are used. One matches the upper end of draw call count in samples of modern games and the other is an exaggerated size to test viability for even larger ones. Graphics processing unit (GPU) time is measured along with total execution time to provide numbers on the overhead time caused by the different recording strategies. Results. When considering the frequency of incremental updates, the multi-draw indirect (MDI) strategy performs very well, outperforming the other strategies even with 100% updates compared to 0% of the others. However, it scales poorly with increasing number of pipeline switches, where the other incremental recording strategy performs best instead. In this case, MDI soon becomes more expensive than regular recording. Conclusions. It is shown that the incremental recording strategies have an observable reduction in overhead time, and may be worth considering. With few pipeline switches, MDI is a viable candidate for its performance and ease of implementation. A large ratio of pipeline switches may not be a realistic scenario, but in those cases the device generated commands (DGC) strategy is a better choice than MDI. Note that the DGC strategy does not perform true incremental recording because calls are still recorded by the GPU. Overhead margins are comparatively low in the smaller scene, but even in that case incremental recording could be beneficial because depending on the implementation, one could avoid traversing parts of data structures that remain unchanged. / Bakgrund. Ritanrop i interaktiva applikationer spelas ofta in för varje bild, trots att de redan existerar i minnet från den föregående. Samtidigt har scener en tendens att vara strukturellt stabila; det som existerar för en bild kommer sannolikt existera även för de påföljande. Syfte. Genom att utnyttja observerad tidskoherens i scenstrukturer avser denna uppsats att utforma en lösning för att stegvis spela in ritanrop. Syftet med sådan inspelning är att återanvända det som spelats in tidigare istället för att spela in det på nytt. Två lösningar för inkrementell inspelning implementeras och jämförs med vanlig naiv inspelning med avseende på kringkostnader. En av dem drar nytta av en utökning till grafikgränssnittet Vulkan för att utvärdera indirekta byten av pipeline. Metod. En simulering används som utvärderingsmetod, med en simpel scen där trianglar renderas med individuella ritanrop. Två scenstorlekar används. En av dem matchar övre gränsen för antalet ritanrop i ett urval av moderna spel, och den andra är en överdriven storlek för att testa lämpligheten i ännu större scener. GPU-tid mäts tillsammans med total exekveringstid för att tillhandahålla siffror på den kringkostnad som orsakas av de olika inspelningsstrategierna. Resultat. När frekvensen av inkrementella uppdateringar beaktas presterar multi-draw indirect (MDI) mycket bra, som vinner över de övriga strategierna även med 100% uppdateringar jämfört med de övrigas 0%. Den skalar dock undermåligt då antal pipeline-byten ökar, där den andra inkrementella inspelningsstrategin istället presterar bäst. I detta fall blir MDI snabbt dyrare än vanlig inspelning. Slutsatser. Det visas att de inkrementella inspelningsstrategierna märkbart reducerar kringkostnad och att de därmed är värda att ha i åtanke. Vid få pipeline-byten är MDI en lämplig kandidat tack vare dess prestanda och enkla implementation. Större förhållanden av pipeline-byten är inte nödvändigtvis ett realistiskt scenario, men i dessa fall är device generated commands (DGC) ett bättre val än MDI. Notera att DGC-strategin inte utför sann inkrementell inspelning eftersom kommandon fortfarande spelas in på GPU:n. Kringkostnadsmarginaler är förhållandevis låga i den mindre scenen, men även där kan inkrementell inspelning vara förmånlig eftersom man då, beroende på implementation, skulle kunna undvika att vandra genom delar av datastrukturer som förblivit oförändrade.

L'un des buts principaux de l'imagerie numérique est d'une part la capture et d'autre part la reproduction de scènes réelles ou synthétiques sur des dispositifs d'affichage aux capacités restreintes. Les techniques d'imagerie traditionnelles sont limitées par la gamme de luminance qu'elles peuvent capturer et afficher. L'imagerie à grande gamme de luminance (High Dynamic Range – HDR) vise à dépasser cette limitation en capturant, représentant et affichant les quantités physique de la lumière présente dans une scène. Cependant, les technologies d'affichage existantes ne vont pas disparaitre instantanément, la compatibilité entre ces nouveaux contenus HDR et les contenus classiques est donc requise. Cette compatibilité est assurée par une opération de réduction des gammes de luminance (tone mapping) qui adapte les contenus HDR aux capacités restreintes des écrans. Bien que de nombreux opérateurs de tone mapping existent, ceux-ci se focalisent principalement sur les images fixes. Les verrous scientifiques associés au tone mapping de vidéo HDR sont plus complexes du fait de la dimension temporelle. Les travaux recherche menés dans la thèse se sont focalisés sur la préservation de la cohérence temporelle du vidéo tone mapping. Deux principaux axes de recherche ont été traités : la qualité subjective de contenus tone mappés et l'efficacité de la compression des vidéos HDR. En effet, tone mapper individuellement chaque image d'une séquence vidéo HDR engendre des artefacts temporels. Ces artefacts affectent la qualité visuelle de la vidéo tone mappée et il est donc nécessaire de les minimiser. Au travers de tests effectués sur des vidéos HDR avec différents opérateurs de tone mapping, nous avons proposé une classification des artefacts temporels en six catégories. Après avoir testé les opérateurs de tone mapping vidéo existants sur les différents types d'artefacts temporels, nous avons observé que seulement trois des six types d'artefacts étaient résolus. Nous avons donc créé une technique de post-traitement qui permet de réduire les 3 types d'artefacts non-considérés. Le deuxième aspect considéré dans la thèse concerne les relations entre compression et tone mapping. Jusque là, les travaux effectués sur le tone mapping et la vidéo compression se focalisaient sur l'optimisation du tone mapping de manière à atteindre des taux de compression élevés. Ces techniques modifient fortement le rendu, c'est à dire l'aspect de la vidéo, modifiant ainsi l'intention artistique initiale en amont dans la chaine de distribution (avant la compression). Dans ce contexte, nous avons proposé une technique qui permet de réduire l'entropie d'une vidéo tone mappée sans en modifier son rendu. Notre méthode adapte la quantification afin d'accroitre les corrélations entre images successives d'une vidéo. / One of the main goals of digital imagery is to improve the capture and the reproduction of real or synthetic scenes on display devices with restricted capabilities. Standard imagery techniques are limited with respect to the dynamic range that they can capture and reproduce. High Dynamic Range (HDR) imagery aims at overcoming these limitations by capturing, representing and displaying the physical value of light measured in a scene. However, current commercial displays will not vanish instantly hence backward compatibility between HDR content and those displays is required. This compatibility is ensured through an operation called tone mapping that retargets the dynamic range of HDR content to the restricted dynamic range of a display device. Although many tone mapping operators exist, they focus mostly on still images. The challenges of tone mapping HDR videos are more complex than those of still images since the temporal dimensions is added. In this work, the focus was on the preservation of temporal coherency when performing video tone mapping. Two main research avenues are investigated: the subjective quality of tone mapped video content and their compression efficiency. Indeed, tone mapping independently each frame of a video sequence leads to temporal artifacts. Those artifacts impair the visual quality of the tone mapped video sequence and need to be reduced. Through experimentations with HDR videos and Tone Mapping Operators (TMOs), we categorized temporal artifacts into six categories. We tested video tone mapping operators (techniques that take into account more than a single frame) on the different types of temporal artifact and we observed that they could handle only three out of the six types. Consequently, we designed a post-processing technique that adapts to any tone mapping operator and reduces the three types of artifact not dealt with. A subjective evaluation reported that our technique always preserves or increases the subjective quality of tone mapped content for the sequences and TMOs tested. The second topic investigated was the compression of tone mapped video content. So far, work on tone mapping and video compression focused on optimizing a tone map curve to achieve high compression ratio. These techniques changed the rendering of the video to reduce its entropy hence removing any artistic intent or constraint on the final results. That is why, we proposed a technique that reduces the entropy of a tone mapped video without altering its rendering.

This masters thesis is focused around the comparison of time dependent video grayscale conversion methods based on a user experiment. The test methodology is based on the pairwise comparison method 2AFC. It is composed of two test variants: a test with a reference video and a test without a reference video. The coefficients of agreement, consistency and correlation are utilized in the result analysis. The testing was done on 60 subjects which have done 7200 pairwise comparisons. The test results show that the time dependent method Hu14 is the most universal. Time dependent method Kim09 was bested by some non-dependent methods. The results also indicate that there is some correlation between the two test variants and that the choice of the input video can have impact on the method performance. The main contribution of this thesis is that non-dependent methods can under certain circumstances rival the performance of dependent methods and that the addition of a reference video did not have a meaningful impact on the test subjects judgements.

The diploma thesis provides the theoretical background needed to understand the complex topic of high dynamic range, and deals with the implementation of an innovative method for temporal video tone-mapping. At first, high dynamic range image acquisition, storage and processing are described. Afterwards, a general introduction to tone-mapping, description of undesirable image artifacts and an overview of existing state-of-the-art algorithms are presented. The part which follows focuses on the implementation of the chosen method and proposes several additional enhancements of the initially selected algorithm. Based on the information provided, an application with an intuitive graphical interface, which can be used for temporal HDR video tone-mapping, has been created. Finally, the the achieved results are demonstrated and visually compared with existing methods for temporal video tone-mapping.

Made available in DSpace on 2014-12-17T15:48:13Z (GMT). No. of bitstreams: 1 LaurindoSBN.pdf: 1520391 bytes, checksum: 86f5072a56e661766a5174bce88b82d5 (MD5) Previous issue date: 2007-09-21 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Non-Photorealisitc Rendering (NPR) is a class of techniques that aims to reproduce artistic techniques, trying to express feelings and moods on the rendered scenes, giving an aspect of that they had been made "by hand". Another way of defining NPR is that it is the processing of scenes, images or videos into artwork, generating scenes, images or videos that can have the visual appeal of pieces of art, expressing the visual and emotional characteristics of artistic styles. This dissertation presents a new method of NPR for stylization of images and videos, based on a typical artistic expression of the Northeast region of Brazil, that uses colored sand to compose landscape images on the inner surface of glass bottles. This method is comprised by one technique for generating 2D procedural textures of sand, and two techniques that mimic effects created by the artists using their tools. It also presents a method for generating 21 2D animations in sandbox from the stylized video. The temporal coherence within these stylized videos can be enforced on individual objects with the aid of a video segmentation algorithm. The present techniques in this work were used on stylization of synthetic and real videos, something close to impossible to be produced by artist in real life / Renderiza??o N?o Fotoreal?stica (NPR) ? uma classe de t?cnicas que almejam reproduzir t?cnicas art?sticas, tentado expressar sentimentos e emo??es nas cenas renderizadas, dando um aspecto de que foram feitas "manualmente". Outra forma de definir a NPR ? como o processamento de cenas, imagens ou v?deos para gera??o de trabalhos de arte, gerando cenas, imagens ou v?deos que podem ter o atrativo visual de pe?as art?sticas, expressando caracter?sticas visuais e emocionais do estilo art?stico. Esta disserta??o apresenta um novo m?todo de NPR para estiliza??o de imagens e v?deos baseado em uma express?o art?stica t?pica da regi?o Nordeste do Brasil, que usa areia colorida para compor imagens de paisagens na superf?cie interna de garrafas de vidro. Este m?todo possui uma t?cnica para gera??o de texturas procedurais de areia 2D, e duas t?cnicas que imitam os efeitos criados pelos artes?es usando sua ferramenta. Al?m disso, essa disserta??o apresenta tamb?m um m?todo para gera??o de anima??es 21 2D em caixas de areia a partir do v?deo estilizado. A coer?ncia temporal nos v?deos estilizados pode ser for?ada nos objetos individuais do v?deo com aux?lio de um algoritmo de segmenta??o de v?deo. As t?cnicas apresentadas neste trabalho s?o usadas na estiliza??o de v?deos reais e sint?ticos, algo quase imposs?vel de ser produzido pelo artes?o na vida real