Practical 3D Reconstruction of Cultural Heritage Artefacts from Photographs – Potentials and Issues

[EN] A new technology is on the rise that allows the 3D-reconstruction of Cultural Heritage objects from image sequences taken by ordinary digital cameras. We describe the first experiments we made as early adopters in a community-funded research project whose goal is to develop it into a standard CH technology. The paper describes in detail a step-by-step procedure that can be reproduced using free tools by any CH professional. We also give a critical assessment of the workflow and describe several ideas for developing it further into an automatic procedure for 3D reconstruction from images.We gratefully acknowledge the funding from the European Commission for the FP7-IP 3D-COFORM under grant No. 231809. With this support, we are confident to provide solutions for the mentioned problems soon.Fellner, DW.; Havemann, S.; Beckmann, P.; Pan, X. (2011). Practical 3D Reconstruction of Cultural Heritage Artefacts from Photographs – Potentials and Issues. Virtual Archaeology Review. 2(4):95-103. https://doi.org/10.4995/var.2011.4564OJS9510324CROFTS N., DOERR M., GILL T., STEAD S., STIFF M.: Definition of the CIDOC Conceptual Reference Model, version 4.2 ed. CIDOC Documentation Standards Working Group, June 2005. Also ISO/PRF 21127, available from cidoc.ics.forth.gr.LONDON CHARTER INITIATIVE (HUGH DENARD): The london charter, June 2006. www.londoncharter.org.PAN, X., BECKMANN, P., HAVEMANN, S., TZOMPANAKI, K., DOERR, M., FELLNER, D.W., A distributed Object Repository for Cultural Heritage, Proc. VAST 2010 conference, Eurographics Press, 201

Fine‐Grained Memory Profiling of GPGPU Kernels

Memory performance is a crucial bottleneck in many GPGPU applications, making optimizations for hardware and software mandatory. While hardware vendors already use highly efficient caching architectures, software engineers usually have to organize their data accordingly in order to efficiently make use of these, requiring deep knowledge of the actual hardware. In this paper we present a novel technique for fine‐grained memory profiling that simulates the whole pipeline of memory flow and finally accumulates profiling values in a way that the user retains information about the potential region in the GPU program by showing these values separately for each allocation. Our memory simulator turns out to outperform state‐of‐the‐art memory models of NVIDIA architectures by a magnitude of 2.4 for the L1 cache and 1.3 for the L2 cache, in terms of accuracy. Additionally, we find our technique of fine grained memory profiling a useful tool for memory optimizations, which we successfully show in case of ray tracing and machine learning applications

LIFE-SHARE Project: Developing a Digitisation Strategy Toolkit

This poster will outline the Digitisation Strategy Toolkit created as part of the LIFE-SHARE project. The toolkit is based on the lifecycle model created by the LIFE project and explores the creation, acquisition, ingest, preservation (bit-stream and content) and access requirements for a digitisation strategy. This covers the policies and infrastructure required in libraries to establish successful practices. The toolkit also provides both internal and external resources to support the service. This poster will illustrate how the toolkit works effectively to support digitisation with examples from three case studies at the Universities of Leeds, Sheffield and York

OLBVH: octree linear bounding volume hierarchy for volumetric meshes

We present a novel bounding volume hierarchy for GPU-accelerated direct volume rendering (DVR) as well as volumetric mesh slicing and inside-outside intersection testing. Our novel octree-based data structure is laid out linearly in memory using space filling Morton curves. As our new data structure results in tightly fitting bounding volumes, boundary markers can be associated with nodes in the hierarchy. These markers can be used to speed up all three use cases that we examine. In addition, our data structure is memory-efficient, reducing memory consumption by up to 75%. Tree depth and memory consumption can be controlled using a parameterized heuristic during construction. This allows for significantly shorter construction times compared to the state of the art. For GPU-accelerated DVR, we achieve performance gain of 8.4×–13×. For 3D printing, we present an efficient conservative slicing method that results in a 3×–25× speedup when using our data structure. Furthermore, we improve volumetric mesh intersection testing speed by 5×–52×

Reconstructing Bounding Volume Hierarchies from Memory Traces of Ray Tracers

The ongoing race to improve computer graphics leads to more complex GPU hardware and ray tracing techniques whose internal functionality is sometimes hidden to the user. Bounding volume hierarchies and their construction are an important performance aspect of such ray tracing implementations. We propose a novel approach that utilizes binary instrumentation to collect memory traces and then uses them to extract the bounding volume hierarchy (BVH) by analyzing access patters. Our reconstruction allows combining memory traces captured from multiple ray tracing views independently, increasing the reconstruction result. It reaches accuracies of 30% to 45% when comparing against the ground-truth BVH used for ray tracing a single view on a simple scene with one object. With multiple views it is even possible to reconstruct the whole BVH, while we already achieve 98% with just seven views. Because our approach is largely independent of the data structures used internally, these accurate reconstructions serve as a first step into estimation of unknown construction techniques of ray tracing implementations

Dithered Color Quantization

Image quantization and digital halftoning are fundamental problems in computer graphics, which arise when displaying high-color images on non-truecolor devices. Both steps are generally performed sequentially and, in most cases, independent of each other. Color quantization with a pixel-wise defined distortion measure and the dithering process with its local neighborhood optimize different quality criteria or, frequently, follow a heuristic without reference to any quality measure. In this paper we propose a new method to simultaneously quantize and dither color images. The method is based on a rigorous cost–function approach which optimizes a quality criterion derived from a generic model of human perception. A highly efficient algorithm for optimization based on a multiscale method is developed for the dithered color quantization cost function. The quality criterion and the optimization algorithms are evaluated on a representative set of artificial and real–world images as well as on a collection of icons. A significant image quality improvement is observed compared to standard color reduction approaches

Human-Centric Chronographics:Making Historical Time Memorable

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Depth of Field Segmentation for Near-Lossless Image Compression and 3D Reconstruction

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Alignment and Reassembly of Broken Specimens for Creep Ductility Measurements

Designing new types of heat-resistant steel components is an important and active research field in material science. It requires detailed knowledge of the inherent steel properties, especially concerning their creep ductility. Highly precise automatic state-of-the-art approaches for such measurements are very expensive and often times invasive. The alternative requires manual work from specialists and is time consuming and unrobust. In this paper, we present a novel approach that uses a photometric scanning system for capturing the geometry of steel specimens, making further measurement extractions possible. In our proposed system, we apply calibration for pan angles that occur during capturing and a robust reassembly for matching two broken specimen pieces to extract the specimen's geometry. We compare our results against µCT scans and found that it deviates by 0.057mm on average distributed over the whole specimen for a small amount of 36 captured images. Additionally, comparisons to manually measured values indicate that our system leads to more robust measurements