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Item Interactive Depixelization of Pixel Art through Spring Simulation(The Eurographics Association and John Wiley & Sons Ltd., 2023) Matusovic, Marko; Parakkat, Amal Dev; Eisemann, Elmar; Myszkowski, Karol; Niessner, MatthiasWe introduce an approach for converting pixel art into high-quality vector images. While much progress has been made on automatic conversion, there is an inherent ambiguity in pixel art, which can lead to a mismatch with the artist's original intent. Further, there is room for incorporating aesthetic preferences during the conversion. In consequence, this work introduces an interactive framework to enable users to guide the conversion process towards high-quality vector illustrations. A key idea of the method is to cast the conversion process into a spring-system optimization that can be influenced by the user. Hereby, it is possible to resolve various ambiguities that cannot be handled by an automatic algorithm.Item A Multi-pass Method for Accelerated Spectral Sampling(The Eurographics Association and John Wiley & Sons Ltd., 2021) Ruit, Mark van de; Eisemann, Elmar; Zhang, Fang-Lue and Eisemann, Elmar and Singh, KaranSpectral Monte Carlo rendering can simulate advanced light phenomena, such as chromatic dispersion, but typically shows a slow convergence behavior. Properly sampling the spectral domain can be challenging in scenes with many complex spectral distributions. To this end, we propose a multi-pass approach. We build and store coarse screen-space estimates of incident spectral radiance and use these to then importance sample the spectral domain. Hereby, we lower variance and reduce noise with little overhead. Our method handles challenging scenarios with difficult spectral distributions, many different emitters, and participating media. Finally, it can be integrated into existing spectral rendering methods for an additional acceleration.Item Editing Compressed High-resolution Voxel Scenes with Attributes(The Eurographics Association and John Wiley & Sons Ltd., 2023) Molenaar, Mathijs; Eisemann, Elmar; Myszkowski, Karol; Niessner, MatthiasSparse Voxel Directed Acyclic Graphs (SVDAGs) are an efficient solution for storing high-resolution voxel geometry. Recently, algorithms for the interactive modification of SVDAGs have been proposed that maintain the compressed geometric representation. Nevertheless, voxel attributes, such as colours, require an uncompressed storage, which can result in high memory usage over the course of the application. The reason is the high cost of existing attribute-compression schemes which remain unfit for interactive applications. In this paper, we introduce two attribute compression methods (lossless and lossy), which enable the interactive editing of compressed high-resolution voxel scenes including attributes.Item Pacific Graphics 2021 - CGF 40-7: Frontmatter(The Eurographics Association and John Wiley & Sons Ltd., 2021) Zhang, Fang-Lue; Eisemann, Elmar; Singh, Karan; Zhang, Fang-Lue and Eisemann, Elmar and Singh, KaranItem Geometric Sample Reweighting for Monte Carlo Integration(The Eurographics Association and John Wiley & Sons Ltd., 2021) Guo, Jerry Jinfeng; Eisemann, Elmar; Zhang, Fang-Lue and Eisemann, Elmar and Singh, KaranNumerical integration is fundamental in multiple Monte Carlo rendering problems. We present a sample reweighting scheme, including underlying theory, and analysis of numerical performance for the integration of an unknown one-dimensional function. Our method is simple to implement and builds upon the insight to link the weights to a function reconstruction process during integration. We provide proof that our solution is unbiased in one-dimensional cases and consistent in multi-dimensional cases. We illustrate its effectiveness in several use cases.