Real-time content-aware texturing for deformable surfaces

Animation of models often introduces distortions to their parameterisation, as these are typically optimised for a single frame. The net effect is that under deformation, the mapped features, i.e. UV texture maps, bump maps or displacement maps, may appear to stretch or scale in an undesirable way. Ideally, what we would like is for the appearance of such features to remain feasible given any underlying deformation. In this paper we introduce a real-time technique that reduces such distortions based on a distortion control (rigidity) map. In two versions of our proposed technique, the parameter space is warped in either an axis or a non-axis aligned manner based on the minimisation of a non-linear distortion metric. This in turn is solved using a highly optimised hybrid CPU-GPU strategy. The result is real-time dynamic content-aware texturing that reduces distortions in a controlled way. The technique can be applied to reduce distortions in a variety of scenarios, including reusing a low geometric complexity animated sequence with a multitude of detail maps, dynamic procedurally defined features mapped on deformable geometry and animation authoring previews on texture-mapped models. © 2013 ACM

Live Texturing of Augmented Reality Characters from Colored Drawings

Coloring books capture the imagination of children and provide them with one of their earliest opportunities for creative expression. However, given the proliferation and popularity of digital devices, real-world activities like coloring can seem unexciting, and children become less engaged in them. Augmented reality holds unique potential to impact this situation by providing a bridge between real-world activities and digital enhancements. In this paper, we present an augmented reality coloring book App in which children color characters in a printed coloring book and inspect their work using a mobile device. The drawing is detected and tracked, and the video stream is augmented with an animated 3-D version of the character that is textured according to the child's coloring. This is possible thanks to several novel technical contributions. We present a texturing process that applies the captured texture from a 2-D colored drawing to both the visible and occluded regions of a 3-D character in real time. We develop a deformable surface tracking method designed for colored drawings that uses a new outlier rejection algorithm for real-time tracking and surface deformation recovery. We present a content creation pipeline to efficiently create the 2-D and 3-D content. And, finally, we validate our work with two user studies that examine the quality of our texturing algorithm and the overall App experience

Extracting Triangular 3D Models, Materials, and Lighting From Images

We present an efficient method for joint optimization of topology, materials and lighting from multi-view image observations. Unlike recent multi-view reconstruction approaches, which typically produce entangled 3D representations encoded in neural networks, we output triangle meshes with spatially-varying materials and environment lighting that can be deployed in any traditional graphics engine unmodified. We leverage recent work in differentiable rendering, coordinate-based networks to compactly represent volumetric texturing, alongside differentiable marching tetrahedrons to enable gradient-based optimization directly on the surface mesh. Finally, we introduce a differentiable formulation of the split sum approximation of environment lighting to efficiently recover all-frequency lighting. Experiments show our extracted models used in advanced scene editing, material decomposition, and high quality view interpolation, all running at interactive rates in triangle-based renderers (rasterizers and path tracers). Project website: https://nvlabs.github.io/nvdiffrec/ .Comment: Project website: https://nvlabs.github.io/nvdiffrec

Survey of texture mapping techniques for representing and rendering volumetric mesostructure

Representation and rendering of volumetric mesostructure using texture mapping can potentially allow the display of highly detailed, animated surfaces at a low performance cost. Given the need for consistently more detailed and dynamic worlds rendered in real-time, volumetric texture mapping now becomes an area of great importance.In this survey, we review the developments of algorithms and techniques for representing volumetric mesostructure as texture-mapped detail. Our goal is to provide researchers with an overview of novel contributions to volumetric texture mapping as a starting point for further research and developers with a comparative review of techniques, giving insight into which methods would be fitting for particular tasks.We start by defining the scope of our domain and provide background information regarding mesostructure and volumetric texture mapping. Existing techniques are assessed in terms of content representation and storage as well as quality and performance of parameterization and rendering. Finally, we provide insights to the field and opportunities for research directions in terms of real-time volumetric texture-mapped surfaces under deformation

Novel Views of Objects from a Single Image

Taking an image of an object is at its core a lossy process. The rich information about the three-dimensional structure of the world is flattened to an image plane and decisions such as viewpoint and camera parameters are final and not easily revertible. As a consequence, possibilities of changing viewpoint are limited. Given a single image depicting an object, novel-view synthesis is the task of generating new images that render the object from a different viewpoint than the one given. The main difficulty is to synthesize the parts that are disoccluded; disocclusion occurs when parts of an object are hidden by the object itself under a specific viewpoint. In this work, we show how to improve novel-view synthesis by making use of the correlations observed in 3D models and applying them to new image instances. We propose a technique to use the structural information extracted from a 3D model that matches the image object in terms of viewpoint and shape. For the latter part, we propose an efficient 2D-to-3D alignment method that associates precisely the image appearance with the 3D model geometry with minimal user interaction. Our technique is able to simulate plausible viewpoint changes for a variety of object classes within seconds. Additionally, we show that our synthesized images can be used as additional training data that improves the performance of standard object detectors

Viewpoint-Free Photography for Virtual Reality

Viewpoint-free photography, i.e., interactively controlling the viewpoint of a photograph after capture, is a standing challenge. In this thesis, we investigate algorithms to enable viewpoint-free photography for virtual reality (VR) from casual capture, i.e., from footage easily captured with consumer cameras. We build on an extensive body of work in image-based rendering (IBR). Given images of an object or scene, IBR methods aim to predict the appearance of an image taken from a novel perspective. Most IBR methods focus on full or near-interpolation, where the output viewpoints either lie directly between captured images, or nearby. These methods are not suitable for VR, where the user has significant range of motion and can look in all directions. Thus, it is essential to create viewpoint-free photos with a wide field-of-view and sufficient positional freedom to cover the range of motion a user might experience in VR. We focus on two VR experiences: 1) Seated VR experiences, where the user can lean in different directions. This simplifies the problem, as the scene is only observed from a small range of viewpoints. Thus, we focus on easy capture, showing how to turn panorama-style capture into 3D photos, a simple representation for viewpoint-free photos, and also how to speed up processing so users can see the final result on-site. 2) Room-scale VR experiences, where the user can explore vastly different perspectives. This is challenging: More input footage is needed, maintaining real-time display rates becomes difficult, view-dependent appearance and object backsides need to be modelled, all while preventing noticeable mistakes. We address these challenges by: (1) creating refined geometry for each input photograph, (2) using a fast tiled rendering algorithm to achieve real-time display rates, and (3) using a convolutional neural network to hide visual mistakes during compositing. Overall, we provide evidence that viewpoint-free photography is feasible from casual capture. We thoroughly compare with the state-of-the-art, showing that our methods achieve both a numerical improvement and a clear increase in visual quality for both seated and room-scale VR experiences

Simulation of 3D Model, Shape, and Appearance Aging by Physical, Chemical, Biological, Environmental, and Weathering Effects

Physical, chemical, biological, environmental, and weathering effects produce a range of 3D model, shape, and appearance changes. Time introduces an assortment of aging, weathering, and decay processes such as dust, mold, patina, and fractures. These time-varying imperfections provide the viewer with important visual cues for realism and age. Existing approaches that create realistic aging effects still require an excessive amount of time and effort by extremely skilled artists to tediously hand fashion blemishes or simulate simple procedural rules. Most techniques do not scale well to large virtual environments. These limitations have prevented widespread utilization of many aging and weathering algorithms. We introduce a novel method for geometrically and visually simulating these processes in order to create visually realistic scenes. This work proposes the ``mu-ton system, a framework for scattering numerous mu-ton particles throughout an environment to mutate and age the world. We take a point based representation to discretize both the decay effects and the underlying geometry. The mu-ton particles simulate interactions between multiple phenomena. This mutation process changes both the physical properties of the external surface layer and the internal volume substrate. The mutation may add or subtract imperfections into the environment as objects age. First we review related work in aging and weathering, and illustrate the limitations of the current data-driven and physically based approaches. We provide a taxonomy of aging processes. We then describe the structure for our ``mu-ton framework, and we provide the user a short tutorial how to setup different effects. The first application of the ``mu-ton system focuses on inorganic aging and decay. We demonstrate changing material properties on a variety of objects, and simulate their transformation. We show the application of our system aging a simple city alley on different materials. The second application of the ``mu-ton system focuses organic aging. We provide details on simulating a variety of growth processes. We then evaluate and analyze the ``mu-ton framework and compare our results with ``gamma-ton tracing. Finally, we outline the contributions this thesis provides to computer-based aging and weathering simulation