{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"id":[{"id":"https:\/\/ror.org\/03mb6wj31","id-type":"ROR","asserted-by":"publisher"},{"id":"https:\/\/www.isni.org\/000000041937028X","id-type":"ISNI","asserted-by":"publisher"},{"id":"https:\/\/www.wikidata.org\/entity\/Q1640731","id-type":"wikidata","asserted-by":"publisher"}],"name":"Universitat Polit\u00e8cnica de Catalunya","acronym":["UPC"]}],"indexed":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T17:17:06Z","timestamp":1770398226174,"version":"3.49.0"},"reference-count":0,"publisher":"Universitat Polit\u00e8cnica de Catalunya","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:p>Per al c\u00e0lcul de la il\u00b7luminaci\u00f3 global per a la s\u00edntesi d'imatges d'escenaris virtuals s'usen m\u00e8todes f\u00edsicament acurats com a radiositat o el ray-tracing. Aquests m\u00e8todes s\u00f3n molt potents i capa\u00e7os de generar imatges de gran realisme, per\u00f2 s\u00f3n molt costosos. A aquesta tesi presenta algunes t\u00e8cniques per simular i\/o accelerar el c\u00e0lcul de la il\u00b7luminaci\u00f3 global. La t\u00e8cnica de les obscurances es basa en la suposici\u00f3 que com m\u00e9s amagat \u00e9s un punt a l'escena, m\u00e9s fosc s'ha de veure. Es calcula analitzant l'entorn geom\u00e8tric del punt i ens d\u00f3na un valor per a la seva il\u00b7luminaci\u00f3 indirecta, que no \u00e9s f\u00edsicament acurat, per\u00f2 s\u00ed aparentment realista.&lt;br\/&gt;Aquesta t\u00e8cnica es millora per a entorns en temps real com els videojocs. S'aplica tamb\u00e9 a entorns de ray-tracing per a la generaci\u00f3 d'imatges realistes. En aquest context, el c\u00e0lcul de seq\u00fc\u00e8ncies de frames per a l'animaci\u00f3 de llums i c\u00e0meres s'accelera enormement reusant informaci\u00f3 entre frames.&lt;br\/&gt;&lt;br\/&gt;Les obscurances serveixen per a simular la il\u00b7luminaci\u00f3 indirecta d'una escena. La llum directa es calcula apart i de manera independent. El desacoblament de la llum directa i la indirecta \u00e9s una gran avantatge, i en treurem profit. Podem afegir f\u00e0cilment l'efecte de coloraci\u00f3 entre objectes sense afegir temps de c\u00e0lcul. Una altra avantatge \u00e9s que per calcular les obscurances nom\u00e9s hem d'analitzar un entorn limitat al voltant del punt.&lt;br\/&gt;&lt;br\/&gt;Per escenes virtuals difuses, la radiositat es pot precalcular i l'escena es pot navegar amb apari\u00e8ncia realista, per\u00f2 si un objecte de l'escena es mou en un entorn din\u00e0mic en temps real, com un videojoc, el rec\u00e0lcul de la il\u00b7luminaci\u00f3 global de l'escena \u00e9s prohibitiu. Com les obscurances es calculen en un entorn limitat, es poden recalcular en temps real per a l'entorn de l'objecte que es mou a cada frame i encara aconseguir temps real.&lt;br\/&gt;&lt;br\/&gt;A m\u00e9s, podem fer servir les obscurances per a calcular imatges de gran qualitat, o per seq\u00fc\u00e8ncies d'imatges per una animaci\u00f3, com en el ray-tracing. Aix\u00f2 ens permet tractar materials no difusos i investigar l'\u00fas de t\u00e8cniques normalment difuses com les obscurances en entorns generals. Quan la c\u00e0mera est\u00e0 est\u00e0tica, l'\u00fas d'animaci\u00f3 de llum nom\u00e9s afecta la il\u00b7luminaci\u00f3 directa, i si usem obscurances per a la llum indirecta, gr\u00e0cies al seu desacoblament, el c\u00e0lcul de s\u00e8ries de frames per a una animaci\u00f3 \u00e9s molt r\u00e0pid. El seg\u00fcent pas \u00e9s afegir animaci\u00f3 de c\u00e0mera, reusant els valors de les obscurances entre frames. &lt;br\/&gt;&lt;br\/&gt;Aquesta \u00faltima t\u00e8cnica de re\u00fas d'informaci\u00f3 de la il\u00b7luminaci\u00f3 del punt d'impacte entre frames la podem usar per a t\u00e8cniques acurades d'il\u00b7luminaci\u00f3 global com el path-tracing, i nosaltres estudiem com reusar aquesta informaci\u00f3 de manera no esbiaixada. &lt;br\/&gt;&lt;br\/&gt;A m\u00e9s, estudiem diferents t\u00e8cniques de mostreig per a la semi-esfera, i les obscurances es calculen amb una nova t\u00e8cnica, aplicant depth peeling amb GPU.<\/jats:p>\n                <jats:p>To compute global illumination solutions for rendering virtual scenes, physically accurate methods based on radiosity or ray-tracing are usually employed. These methods, though powerful and capable of generating images with high realism, are very costly. In this thesis, some techniques to simulate and\/or accelerate the computation of global illumination are studied. The obscurances technique is based on the supposition that the more occluded is a point in the scene, the darker it will appear. It is computed by analyzing the geometric environment of the point and gives a value for the indirect illumination for the point that is, though not physically accurate, visually realistic. This technique is enhanced and improved in real-time environments as videogames. It is also applied to ray-tracing frameworks to generate realistic images. In this last context, sequences of frames for animation of lights and cameras are dramatically accelerated by reusing information between frames.&lt;br\/&gt;&lt;br\/&gt;The obscurances are computed to simulate the indirect illumination of a scene. The direct lighting is computed apart and in an independent way. The decoupling of direct and indirect lighting is a big advantage, and we will take profit from this. We can easily add color bleeding effects without adding computation time. Another advantage is that to compute the obscurances we only need to analyze a limited environment around the point.&lt;br\/&gt;    &lt;br\/&gt;For diffuse virtual scenes, the radiosity can be precomputed and we can navigate the scene with a realistic appearance. But when a small object moves in a dynamic real-time virtual environment, as a videogame, the recomputation of the global illumination of the scene is prohibitive. Thanks to the limited reach of the obscurance computation, we can recompute the obscurances only for the limited environment of the moving object for every frame and still have real-time frame rates.&lt;br\/&gt;    &lt;br\/&gt;Obscurances can also be used to compute high quality images, or sequences of images for an animation, in a ray-tracing-like. This allows us to deal with non-diffuse materials and to research the use of a commonly diffuse technique as obscurances in general environments. For static cameras, using light animation only affects to direct lighting, and if we use obscurances for the indirect lighting, thanks to the decoupling of direct and indirect illumination, the computation of a series of frames for the animation is very fast. The next step is to add camera animation, reusing the obscurances results between frames.&lt;br\/&gt;    &lt;br\/&gt;Using this last technique of reusing the illumination of the hit points between frames for a true global illumination technique as path tracing, we study how we can reuse this information in an unbiased way.&lt;br\/&gt;    &lt;br\/&gt;Besides, a study of different sampling techniques for the hemisphere is made, obscurances are computed with the depth-peeling technique and using GPU.<\/jats:p>","DOI":"10.5821\/dissertation-2117-93960","type":"dissertation","created":{"date-parts":[[2023,10,7]],"date-time":"2023-10-07T01:29:27Z","timestamp":1696642167000},"approved":{"date-parts":[[2007,6,15]]},"source":"Crossref","is-referenced-by-count":0,"title":["Fast photorealistic techniques to simulate global illumination in videogames and virtual environments"],"prefix":"10.5821","author":[{"sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"\u00c0lex","family":"M\u00e9ndez Feliu","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"3865","container-title":[],"original-title":[],"deposited":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T06:32:28Z","timestamp":1770359548000},"score":1,"resource":{"primary":{"URL":"https:\/\/hdl.handle.net\/2117\/93960"}},"subtitle":[],"editor":[{"given":"Mateu","family":"Sbert","sequence":"first","affiliation":[],"role":[{"role":"editor","vocabulary":"crossref"}]}],"short-title":[],"issued":{"date-parts":[[null]]},"references-count":0,"URL":"https:\/\/doi.org\/10.5821\/dissertation-2117-93960","relation":{},"subject":[]}}