6 research outputs found
Motion enriching using humanoide captured motions
Animated humanoid characters are a delight to watch. Nowadays they are extensively
used in simulators. In military applications animated characters are used for training
soldiers, in medical they are used for studying to detect the problems in the joints of a
patient, moreover they can be used for instructing people for an event(such as weather
forecasts or giving a lecture in virtual environment). In addition to these environments
computer games and 3D animation movies are taking the benefit of animated characters
to be more realistic. For all of these mediums motion capture data has a great impact
because of its speed and robustness and the ability to capture various motions.
Motion capture method can be reused to blend various motion styles. Furthermore we
can generate more motions from a single motion data by processing each joint data
individually if a motion is cyclic. If the motion is cyclic it is highly probable that each
joint is defined by combinations of different signals. On the other hand, irrespective of
method selected, creating animation by hand is a time consuming and costly process for
people who are working in the art side. For these reasons we can use the databases
which are open to everyone such as Computer Graphics Laboratory of Carnegie Mellon
University.Creating a new motion from scratch by hand by using some spatial tools (such as 3DS
Max, Maya, Natural Motion Endorphin or Blender) or by reusing motion captured data
has some difficulties. Irrespective of the motion type selected to be animated
(cartoonish, caricaturist or very realistic) human beings are natural experts on any kind
of motion. Since we are experienced with other peoples’ motions, and comparing each
motion to the others, we can easily judge one individual’s mood from his/her body
language. As being a natural master of human motions it is very difficult to convince
people by a humanoid character’s animation since the recreated motions can include
some unnatural artifacts (such as foot-skating, flickering of a joint)
Doctor of Philosophy
dissertationReal-time global illumination is the next frontier in real-time rendering. In an attempt to generate realistic images, games have followed the film industry into physically based shading and will soon begin integrating global illumination techniques. Traditional methods require too much memory and too much time to compute for real-time use. With Modular and Delta Radiance Transfer we precompute a scene-independent, low-frequency basis that allows us to calculate complex indirect lighting calculations in a much lower dimensional subspace with a reduced memory footprint and real-time execution. The results are then applied as a light map on many different scenes. To improve the low frequency results, we also introduce a novel screen space ambient occlusion technique that allows us to generate a smoother result with fewer samples. These three techniques, low and high frequency used together, provide a viable indirect lighting solution that can be run in milliseconds on today's hardware, providing a useful new technique for indirect lighting in real-time graphics
Fast photorealistic techniques to simulate global illumination in videogames and virtual environments
Per al cà lcul de la il·luminació global per a la sÃntesi d'imatges d'escenaris virtuals s'usen mètodes fÃsicament acurats com a radiositat o el ray-tracing. Aquests mètodes són molt potents i capaços de generar imatges de gran realisme, però són molt costosos. A aquesta tesi presenta algunes tècniques per simular i/o accelerar el cà lcul de la il·luminació global. La tècnica de les obscurances es basa en la suposició que com més amagat és un punt a l'escena, més fosc s'ha de veure. Es calcula analitzant l'entorn geomètric del punt i ens dóna un valor per a la seva il·luminació indirecta, que no és fÃsicament acurat, però sà aparentment realista.Aquesta tècnica es millora per a entorns en temps real com els videojocs. S'aplica també a entorns de ray-tracing per a la generació d'imatges realistes. En aquest context, el cà lcul de seqüències de frames per a l'animació de llums i cà meres s'accelera enormement reusant informació entre frames.Les obscurances serveixen per a simular la il·luminació indirecta d'una escena. La llum directa es calcula apart i de manera independent. El desacoblament de la llum directa i la indirecta és una gran avantatge, i en treurem profit. Podem afegir fà cilment l'efecte de coloració entre objectes sense afegir temps de cà lcul. Una altra avantatge és que per calcular les obscurances només hem d'analitzar un entorn limitat al voltant del punt.Per escenes virtuals difuses, la radiositat es pot precalcular i l'escena es pot navegar amb apariència realista, però si un objecte de l'escena es mou en un entorn dinà mic en temps real, com un videojoc, el recà lcul de la il·luminació global de l'escena és 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.A més, podem fer servir les obscurances per a calcular imatges de gran qualitat, o per seqüències d'imatges per una animació, com en el ray-tracing. Això ens permet tractar materials no difusos i investigar l'ús de tècniques normalment difuses com les obscurances en entorns generals. Quan la cà mera està està tica, l'ús d'animació de llum només afecta la il·luminació directa, i si usem obscurances per a la llum indirecta, grà cies al seu desacoblament, el cà lcul de sèries de frames per a una animació és molt rà pid. El següent pas és afegir animació de cà mera, reusant els valors de les obscurances entre frames. Aquesta última tècnica de reús d'informació de la il·luminació del punt d'impacte entre frames la podem usar per a tècniques acurades d'il·luminació global com el path-tracing, i nosaltres estudiem com reusar aquesta informació de manera no esbiaixada. A més, estudiem diferents tècniques de mostreig per a la semi-esfera, i les obscurances es calculen amb una nova tècnica, aplicant depth peeling amb GPU.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.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. 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. 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. 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. Besides, a study of different sampling techniques for the hemisphere is made, obscurances are computed with the depth-peeling technique and using GPU
Abstract Real-Time Ambient Occlusion for Dynamic Character Skins
Figure 1: Time-lapse screen capture showing ambient occlusion values calculated in real-time. We present a single-pass hardware accelerated method to reconstruct compressed ambient occlusion values in real-time on dynamic character skins. This method is designed to work with meshes that are deforming based on a low-dimensional set of parameters, as in character animation. The inputs to our method are rendered ambient occlusion values at the vertices of a mesh deformed into various poses, along with the corresponding degrees of freedom of those poses. The algorithm uses k-means clustering to group the degrees of freedom into a small number of pose clusters. Because the pose variation in a cluster is small, our method can define a low-dimensional pose representation using principal component analysis. Within each cluster, we approximate ambient occlusion as a linear function in the reduced-dimensional representation. When drawing the character, our method uses moving least squares to blend the reconstructed ambient occlusion values from a small number of pose clusters. This technique offers significant memory savings over storing uncompressed values, and can generate plausible ambient occlusion values for poses not seen in training. Because we are using linear functions our output is smooth, fast to evaluate, and easy to implement in a vertex or fragment shader. CR Categories: I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism—Color, shading, shadowing, and textur