Photographic Texture Research Articles

Three-Dimensional Digitization of Documentation and Perpetual Preservation of Cultural Heritage Buildings at Risk of Liquidation and Loss—The Methodology and Case Study of St Adalbert’s Church in Chicago

This paper presents a three-dimensional (3D) digitization methodology for documenting the appearance and geometry of cultural heritage buildings using modern tools for data acquisition and processing. This work presents a method combining laser scanning of building dimensions with photographic texture acquisition techniques in order to develop accurate, photo-realistic 3D models. This work also presents a method for digital reconstruction of the elements of interiors. This case study presents the process and result of scanning the church of St Adalbert in Chicago along with its inner finishing elements, achieved during the interventional 3D scanning of a historical building interior. The obtained colorized point cloud has 3.5 billion points and a volume of 65 GB. Its creation took nearly 3.5 h on a high-end computer. The generated textured mesh model has 1.6 billion triangles and a volume of 60 GB. The analysis of the results showed that the elements of the church furnishings were reproduced with very high accuracy. The developed 3D model of the interior, appearance and dimensions of the church is its perpetual documentation. It can be used for various purposes, such as popularizing the appearance on the Internet, scientific research on interior artefacts, creating files for VR and shooting high-resolution films.

Development of a New Image-Guided Neuronavigation System: Mixed-Reality Projection Mapping Is Accurate and Feasible.

Image-guided systems improve the safety, functional outcome, and overall survival of neurosurgery but require extensive equipment. To develop an image-guided surgery system that combines the brain surface photographic texture (BSP-T) captured during surgery with 3-dimensional computer graphics (3DCG) using projection mapping. Patients who underwent initial surgery with brain tumors were prospectively enrolled. The texture of the 3DCG (3DCG-T) was obtained from 3DCG under similar conditions as those when capturing the brain surface photographs. The position and orientation at the time of 3DCG-T acquisition were used as the reference. The correct position and orientation of the BSP-T were obtained by aligning the BSP-T with the 3DCG-T using normalized mutual information. The BSP-T was combined with and displayed on the 3DCG using projection mapping. This mixed-reality projection mapping (MRPM) was used prospectively in 15 patients (mean age 46.6 yr, 6 males). The difference between the centerlines of surface blood vessels on the BSP-T and 3DCG constituted the target registration error (TRE) and was measured in 16 fields of the craniotomy area. We also measured the time required for image processing. The TRE was measured at 158 locations in the 15 patients, with an average of 1.19±0.14 mm (mean±standard error). The average image processing time was 16.58 min. Our MRPM method does not require extensive equipment while presenting information of patients' anatomy together with medical images in the same coordinate system. It has the potential to improve patient safety.

New metric products, movies, and 3D models from old stereopairs and their application to the in situ palaeontological site of Ambrona

3D modelling tools from photographic pictures have experienced significant improvements in the last years. One of the most outstanding changes is the spread of the photogrammetric systems based on algorithms referred to as Structure from Motion (SfM) in contrast with the traditional stereoscopic pairs. Nevertheless, the availability of important collections of stereoscopic registers collected during past decades invites us to explore the possibilities for re-using these photographs in order to generate new multimedia products, especially due to the fact that many of the documented elements have been largely altered or even disappeared. This article analyses an example of application to the re-use of a collection of photographs from the palaeontological site of Ambrona (Soria, Spain). More specifically, different pieces of software based on Structure from Motion (SfM) algorithms for the generation of 3D models with photographic textures are tested and some derived products such as orthoimages, video or applications of Augmented Reality (AR) are presented.

Fotogrametría SFM aplicada a la determinación taxonómica de restos arqueofaunísticos

<p>Photogrammetry has recently been incorporated into archaeological research, replacing much more expensive techniques while still generating high resolution results. This technique converts two dimensional (2D) images into three-dimensional (3D) models, allowing for the complex analysis of geometric and spatial information. It has become one of the most used methods for the 3D recording of cultural heritage objects. Among its possible archaeological uses are: digitally documenting an archaeological dig at low cost, aiding the decision-making process (Dellepiane et al., 2013); spatial surveying of archaeological sites; 3D model generation of archaeological objects and digitisation of archaeological collections (Adami et al., 2018; Aparicio Resco et al., 2014; Cots et al., 2018; Iturbe et al., 2018; Moyano, 2017).</p><p>The objective of this paper is to show the applicability of 3D models based on SfM (Structure from Motion) photogrammetry for archaeofauna analyses. We created 3D models of four camelid (Lama glama) bone elements (skull, radius-ulna, metatarsus and proximal phalange), aiming to demonstrate the advantages of 3D models over 2D osteological guides, which are usually used to perform anatomical and systematic determination of specimens.</p><p>Photographs were taken with a 16 Megapixel Nikon D5100 DSLR camera mounted on a tripod, with the distance to the object ranging between 1 and 3 m and using a 50mm fixed lens. Each bone element was placed on a 1 m tall stool, with a green, high contrast background. Photographs were shot at regular intervals of 10-15º, moving in a circle. Sets of around 30 pictures were taken from three circumferences at vertical angles of 0º, 45º and 60º. In addition, some detailed and overhead shots were taken from the dorsal and ventral sides of each bone element. Each set of dorsal and ventral photos was imported to Agisoft Photoscan Professional. A workflow (Fig. 4) of alignment, tie point matching, high resolution 3D dense point cloud construction, and creation of a triangular mesh covered with a photographic texture was performed. Finally the dorsal and ventral models were aligned and merged and the 3D model was accurately scaled. In order to determine accuracy of the models, linear measurements were performed and compared to a digital gauge measurement of the physical bones, obtaining a difference of less than 0.5 mm.</p><p>Furthermore, five archaeological specimens were selected to compare our 3D models with the most commonly used 2D camelid atlas (Pacheco Torres et al., 1986; Sierpe, 2015). In the particular case of archaeofaunal analyses, where anatomical and systematic determination of the specimens is the key, digital photogrammetry has proven to be more effective than traditional 2D documentation methods. This is due to the fact that 2D osteological guides based on drawings or pictures lack the necessary viewing angles to perform an adequate and complete diagnosis of the specimens. Using new technology can deliver better results, producing more comprehensive information of the bone element, with great detail and geometrical precision and not limited to pictures or drawings at particular angles. In this paper we can see how 3D modelling with SfM-MVS (Structure from Motion-Multi View Stereo) allows the observation of an element from multiple angles. The possibility of zooming and rotating the models (Figs. 6g, 6h, 7d, 8c) improves the determination of the archaeological specimens.</p><p>Information on how the 3D model was produced is essential. A metadata file must include data on each bone element (anatomical and taxonomic) plus information on photographic quantity and quality. This file must also contain the software used to produce the model and the parameters and resolution of each step of the workflow (number of 3D points, mesh vertices, texture resolution and quantification of the error of the model). In short, 3D models are excellent tools for osteological guides.</p>

A Methodology for Planar Representation of Frescoed Oval Domes: Formulation and Testing on Pisa Cathedral

This paper presents an original methodology for planar development of a frescoed dome with an oval plan. Input data include a rigorous geometric survey, performed with a laser scanner, and a photogrammetry campaign, which associates a high-quality photographic texture to the 3D model. Therefore, the main topics include the development of geometry and, contextually, of the associated textures. In order to overcome the inability to directly develop the surface, an orthographic azimuthal projection is used. Starting from a prerequisite study of building methodology, the dome is divided into sectors and bands, each linked with the maximum acceptable deformations and the actual geometric discontinuities detectable by the analysis of Gaussian curvature. Upon definition of the development model, a custom automation script has been devised for geometry projection. This effectively generates a (u,v) map, associated to the model, which is used for model texturing and provides the planar development of the fresco.

Photogrammetric texture mapping: A method for increasing the Fidelity of 3D models of cultural heritage materials

Accurately recording information is the single most important stage of an archaeological project. The biggest technological improvement to documentation techniques in the last 15 years has been the spread of various 3D digitization technologies, such as computer vision photogrammetry and 3D laser scanning. These technologies have allowed archaeologists to quickly and accurately capture and reconstruct the geometry and colors of the subjects being studied. Each of the various methods for 3D digitization of cultural heritage materials has advantages and disadvantages, such as processing speed, cost of equipment, and the accuracy of the captured data. Laser scanned data is among the most accurate geometrical data available in modern scanning techniques, but it lacks in its ability to accurately capture textures and diagnostic coloration information. Photogrammetric data produces highly detailed photographic textures on models, but the geometric data tends to be of a lower definition than the laser scanned data. In this paper, the authors discuss a new methodology that combines the advantages of computer vision photogrammetry with those of laser scanning by applying the photographic textures produced with photogrammetry to the geometric data obtained from laser scanning. This method allows archaeologists to achieve the best possible fidelity 3D models for interpretation and study.

RECOVERING OLD STEREOSCOPIC NEGATIVES AND PRODUCING DIGITAL 3D MODELS OF FORMER APPEARANCES OF HISTORIC BUILDINGS

Abstract. Three-dimensional models with photographic textures have become a usual product for the study and dissemination of elements of heritage. The interest for cultural heritage also includes evolution along time; therefore, apart from the 3D models of the current state, it is interesting to be able to generate models representing how they were in the past. To that end, it is necessary to resort to archive information corresponding to the moments that we want to visualize. This text analyses the possibilities of generating 3D models of surfaces with photographic textures from old collections of analog negatives coming from works of terrestrial stereoscopic photogrammetry of historic buildings. The case studies presented refer to the geometric documentation of a small hermitage (done in 1996) and two sections of a wall (year 2000). The procedure starts with the digitization of the film negatives and the processing of the images generated, after which a combination of different methods for 3D reconstruction and texture wrapping are applied: techniques working simultaneously with several images (such as the algorithms of Structure from Motion – SfM) and single image techniques (such as the reconstruction based on vanishing points). Then, the features of the obtained models are described according to the geometric accuracy, completeness and aesthetic quality. In this way, it is possible to establish the real applicability of the models in order to be useful for the aforementioned historical studies and dissemination purposes. The text also wants to draw attention to the importance of preserving the documentary heritage available in the collections of negatives in archival custody and to the increasing difficulty of using them due to: (1) problems of access and physical conservation, (2) obsolescence of the equipment for scanning and stereoplotting and (3) the fact that the software for processing digitized photographs is discontinued.

High-resolution 3D surface modeling of a fossil oyster reef

The world’s largest fossil oyster reef, formed by the giant oyster Crassostrea gryphoides and located in Stetten (north of Vienna, Austria), is studied in this article. Digital documentation of the unique geological site is provided by terrestrial laser scanning (TLS) at the millimeter scale. Obtaining meaningful results is not merely a matter of data acquisition with a suitable device; it requires proper planning, data management, and postprocessing. Terrestrial laser scanning technology has a high potential for providing precise 3D mapping that serves as the basis for automatic object detection in different scenarios; however, it faces challenges in the presence of large amounts of data and the irregular geometry of an oyster reef. We provide a detailed description of the techniques and strategy used for data collection and processing. The use of laser scanning provided the ability to measure surface points of 46,840 (estimated) shells. They are up to 60-cm-long oyster specimens, and their surfaces are modeled with a high accuracy of 1 mm. In addition, we propose an automatic analysis method for identifying and enumerating convex parts of shells. Object surfaces were detected with a completeness of 69% and a correctness of over 75% by means of a fully automated workflow. Accuracy of 98% was achieved in detecting the number of objects. In addition to laser scanning measurements, more than 300 photographs were captured, and an orthophoto mosaic was generated with a ground sampling distance (GSD) of 0.5 mm. This high-resolution 3D information and the photographic texture serve as the basis for ongoing and future geological and paleontological analyses. Moreover, they provide unprecedented documentation for conservation issues at a unique natural heritage site.

Reutilización de pares fotogramétricos de elementos arquitectónicos para la obtención de modelos 3D y ortofotografías a partir de técnicas SFM

This paper analyzes the possibility of re-use of photogrammetric stereopairs -originally taken so as to make line drawings (stereoplotting)- and generate 3D models with photographic textures and orthophotographs by means of the techniques called “ structure from motion ” (SFM). The text includes many case studies so it is possible to see the factors defining the quality of the results. Finally, some conclusions are drawn concerning the usefulness of these algorithms for the Building Archaeology.

A Photogrammetric and Computer Vision-Based Approach for Automated 3D Architectural Modeling and Its Typological Analysis

Thanks to the advances in integrating photogrammetry and computer vision, as well as in some numeric algorithms and methods, it is possible to aspire to turn 2D (images) into 3D (point clouds) in an automatic, flexible and good-quality way. This article presents a new method through the development of PW (Photogrammetry Workbench) (and how this could be useful for architectural modeling). This tool enables the user to turn images into scale 3D point cloud models, which have a better quality than those of laser systems. Moreover, the point clouds may include the respective orthophotos with photographic texture. The method allows the study of the typology of architecture and has been successfully tested on a sample of ten religious buildings located in the region of Aliste, Zamora (Spain).

Visualization of Large-Scale Urban Models through Multi-Level Relief Impostors

In this paper, we present an efficient approach for the interactive rendering of large-scale urban models, which can be integrated seamlessly with virtual globe applications. Our scheme fills the gap between standard approaches for distant views of digital terrains and the polygonal models required for close-up views. Our work is oriented towards city models with real photographic textures of the building facades. At the heart of our approach is a multi-resolution tree of the scene defining multi-level relief impostors. Key ingredients of our approach include the pre-computation of a small set of zenithal and oblique relief maps that capture the geometry and appearance of the buildings inside each node, a rendering algorithm combining relief mapping with projective texture mapping which uses only a small subset of the pre-computed relief maps, and the use of wavelet compression to simulate two additional levels of the tree. Our scheme runs considerably faster than polygonal-based approaches while producing images with higher quality than competing relief-mapping techniques. We show both analytically and empirically that multi-level relief impostors are suitable for interactive navigation through large urban models.

Performance-driven facial animation

As computer graphics technique rises to the challenge of rendering lifelike performers, more lifelike performance is required. The techniques used to animate robots, arthropods, and suits of armor, have been extended to flexible surfaces of fur and flesh. Physical models of muscle and skin have been devised. But more complex databases and sophisticated physical modeling do not directly address the performance problem. The gestures and expressions of a human actor are not the solution to a dynamic system. This paper describes a means of acquiring the expressions of real faces, and applying them to computer-generated faces. Such an "electronic mask" offers a means for the traditional talents of actors to be flexibly incorporated in digital animations. Efforts in a similar spirit have resulted in servo-controlled "animatrons," high-technology puppets, and CG puppetry [1]. The manner in which the skills of actors and puppetteers as well as animators are accommodated in such systems may point the way for a more general incorporation of human nuance into our emerging computer media.The ensuing description is divided into two major subjects: the construction of a highly-resoved human head model with photographic texture mapping, and the concept demonstration of a system to animate this model by tracking and applying the expressions of a human performer.

Quantification of textures-textural parameters and their significance for classifying agricultural crop types from colour aerial photographs

This study demonstrates how aerial photographic textures of agricultural crops can be quantified by deriving measures from small square areas that have been converted to digitized arrays. A Zeiss Scanning-Microscope-Photometer 05 was used as a scanning digitizing instrument and measurements were repeated with light of three different wave-lengths. The output in form of a matrix was processed further by statistical methods to evaluate various types of textural parameters: 1. (1) the standard deviation as value for the overall variation around an average value; 2. (2) the average distance between picture elements belonging to the same density class in row direction and in column direction; 3. (3) the average run-length, i.e., the number of picture elements with values in the same class following each other in row direction and in column direction; 4. (4) the probability that a picture element has a neighbouring point with a value in a particular density class in row direction and in column direction. A discriminant analysis was then employed to determined how many crop fields could be classified correctly with these textural parameters.