Critical Factors and Guidelines for 3D Surveying and Modelling in Cultural Heritage
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paper_title: Heritage Recording and 3D Modeling with Photogrammetry and 3D Scanning

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The importance of landscape and heritage recording and documentation with optical remote sensing sensors is well recognized at international level. The continuous development of new sensors, data capture methodologies and multi-resolution 3D representations, contributes significantly to the digital 3D documentation, mapping, conservation and representation of landscapes and heritages and to the growth of research in this field. This article reviews the actual optical 3D measurement sensors and 3D modeling techniques, with their limitations and potentialities, requirements and specifications. Examples of 3D surveying and modeling of heritage sites and objects are also shown throughout the paper.
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paper_title: Image-based 3D Modelling: A Review

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In this paper the main problems and the available solutions are addressed for the generation of 3D models from terrestrial images. Close range photogrammetry has dealt for many years with manual or automatic image measurements for precise 3D modelling. Nowadays 3D scanners are also becoming a standard source for input data in many application areas, but image-based modelling still remains the most complete, economical, portable, flexible and widely used approach. In this paper the full pipeline is presented for 3D modelling from terrestrial image data, considering the different approaches and analysing all the steps involved.
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paper_title: Building reconstruction using manhattan-world grammars

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We present a passive computer vision method that exploits existing mapping and navigation databases in order to automatically create 3D building models. Our method defines a grammar for representing changes in building geometry that approximately follow the Manhattan-world assumption which states there is a predominance of three mutually orthogonal directions in the scene. By using multiple calibrated aerial images, we extend previous Manhattan-world methods to robustly produce a single, coherent, complete geometric model of a building with partial textures. Our method uses an optimization to discover a 3D building geometry that produces the same set of facade orientation changes observed in the captured images. We have applied our method to several real-world buildings and have analyzed our approach using synthetic buildings.
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paper_title: LiDAR or Photogrammetry? Integration is the answer

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In the last few years, LiDAR and image-matching techniques have been employed in many application fields because of their quickness in point cloud generation. Nevertheless, the use of only one of these techniques is not sufficient to extract automatically reliable information. In this paper, an integration approach of these techniques is proposed in order to overcome their individual weakness. The goal of this work is the automated extraction of manmade object outlines in order to reduce the human intervention during the data processing simplifying the work of the users. This approach has been implemented on both terrestrial and aerial applications, showing the reliability and the potentiality of this kind of integration.
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paper_title: Airborne and terrestrial laser scanning

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Whittles Publishing is delighted to announce that Airborne and Terrestrial Laser Scanning has been awarded the Karl Kraus Medal by the ISPRS with the presentation being made on 31st August at the XXII Congress in Melbourne. We are also very pleased for all the authors who have contributed to the book and especially to George Vosselman and Hans-Gerd Maas for their commitment and expertise which has resulted in such an acclaimed and highly successful book. It is gratifying that our growing list of geomatics titles continues to receive recognition and we are endeavouring to create more books that will be equally well-received and useful. ::: ::: Written by a team of international experts, this book provides a comprehensive overview of the major applications of airborne and terrestrial laser scanning. The book focuses on principles and methods and presents an integrated treatment of airborne and terrestrial laser scanning technology. ::: ::: Laser scanning is a relatively young 3D measurement technique offering much potential in the acquisition of precise and reliable 3D geodata and object geometries. However, there are many terrestrial and airborne scanners on the market, accompanied by numerous software packages that handle data acquisition, processing and visualization, yet existing knowledge is fragmented over a wide variety of publications, whether printed or electronic. ::: ::: This book brings together the various facets of the subject in a coherent text that will be relevant for advanced students, academics and practitioners. After consideration of the technology and processing methods, the book turns to applications. The primary use thus far has been the extraction of digital terrain models from airborne laser scanning data, but many other applications are considered including engineering, forestry, cultural heritage, extraction of 3D building models and mobile mapping.
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paper_title: Best practices for the 3D documentation of the Grotta dei Cervi of Porto Badisco, Italy

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The Grotta dei Cervi is a Neolithic cave where human presence has left many unique pictographs on the walls of many ::: of its chambers. It was closed for conservation reasons soon after its discovery in 1970. It is for these reasons that a 3D ::: documentation was started. Two sets of high resolution and detailed three-dimensional (3D) acquisitions were captured ::: in 2005 and 2009 respectively, along with two-dimensional (2D) images. From this information a textured 3D model ::: was produced for most of the 300-m long central corridor. Carbon dating of the guano used for the pictographs and ::: environmental monitoring (Temperature, Relative humidity, and Radon) completed the project. This paper presents this ::: project, some results obtained up to now, the best practice that has emerged from this work and a description of the ::: processing pipeline that deals with more than 27 billion 3D coordinates.
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paper_title: Basic theory on surface measurement uncertainty of 3D imaging systems

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Three-dimensional (3D) imaging systems are now widely available, but standards, best practices and comparative data ::: have started to appear only in the last 10 years or so. The need for standards is mainly driven by users and product ::: developers who are concerned with 1) the applicability of a given system to the task at hand (fit-for-purpose), 2) the ::: ability to fairly compare across instruments, 3) instrument warranty issues, 4) costs savings through 3D imaging. The ::: evaluation and characterization of 3D imaging sensors and algorithms require the definition of metric performance. The ::: performance of a system is usually evaluated using quality parameters such as spatial resolution/uncertainty/accuracy ::: and complexity. These are quality parameters that most people in the field can agree upon. The difficulty arises from ::: defining a common terminology and procedures to quantitatively evaluate them though metrology and standards ::: definitions. This paper reviews the basic principles of 3D imaging systems. Optical triangulation and time delay (timeof- ::: flight) measurement systems were selected to explain the theoretical and experimental strands adopted in this paper. ::: The intrinsic uncertainty of optical distance measurement techniques, the parameterization of a 3D surface and ::: systematic errors are covered. Experimental results on a number of scanners (Surphaser®, HDS6000®, Callidus CPW ::: 8000®, ShapeGrabber® 102) support the theoretical descriptions.
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paper_title: Close-range photogrammetry vs. 3D scanning: Comparing data capture, processing and model generation in the field and the lab

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With the introduction of several affordable and/or free close-range photogrammetric software packages that require minimal processing labor over the past year, much discussion has developed regarding how useful such a cheap and easy 3D capture solution is for archaeologists. When is a point-and-shoot camera sufficient for documenting an excavation or ceramic vessel and when would an expensive laser scanner be required? How does the accuracy and repeatability of these newer close-range photogrammetry options compare with 3D scanning? This paper reviews a variety of non-metric, close-range photogrammetric data capture methods (e.g. calibrated vs. non-calibrated, wide-angle vs. normal lens, etc.) and assess how each resulting data set performs through a comparison of at least three photogrammetric software packages including Eos Systems' PhotoModeler Scanner, AutoDesk's 123D Catch and AgiSoft's PhotoScan. The resulting data sets will be compared to scan data of the same objects as captured by a Leica C10 mid-range laser scanner and the Breuckmann SmartScan HE close-range scanner. Test data will include rock art and architecture from Knowth, Ireland; Defiance House Ruin, United States; architectural sculptures from El Zotz, Guatemala; Wadi Abu Subeira I, El Hosh, Egypt as well as controlled lab tests.
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paper_title: Design and implement a reality-based 3D digitisation and modelling project

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3D digitisation denotes the process of describing parts of our physical world through finite measurements and representations that can be processed and visualised with a computer system. Reality-based 3D digitisation is essential for the documentation, conservation and preservation of our Cultural Heritage. This article composes a critical review of the digitisation pipeline, ranging from sensor selection and planning to data acquisition, processing and visualisation.
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paper_title: From deposit to point cloud: a study of low-cost computer vision approaches for the straightforward documentation of archaeological excavations

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Stratigraphic archaeological excavations demand high-resolution documentation techniques for 3D recording. Today, this is typically accomplished using total stations or terrestrial laser scanners. This paper demonstrates the potential of another technique that is low-cost and easy to execute. It takes advantage of software using Structure from Motion (SfM) algorithms, which are known for their ability to reconstruct camera pose and threedimensional scene geometry (rendered as a sparse point cloud) from a series of overlapping photographs captured by a camera moving around the scene. When complemented by stereo matching algorithms, detailed 3D surface models can be built from such relatively oriented photo collections in a fully automated way. The absolute orientation of the model can be derived by the manual measurement of control points. The approach is extremely flexible and appropriate to deal with a wide variety of imagery, because this computer vision approach can also work with imagery resulting from a randomly moving camera (i.e. uncontrolled conditions) and calibrated optics are not a prerequisite. For a few years, these algorithms are embedded in several free and low-cost software packages. This paper will outline how such a program can be applied to map archaeological excavations in a very fast and uncomplicated way, using imagery shot with a standard compact digital camera (even if the ima ges were not taken for this purpose). Archived data from previous excavations of VIAS-University of Vienna has been chosen and the derived digital surface models and orthophotos have been examined for their usefulness for archaeological applications. The a bsolute georeferencing of the resulting surface models was performed with the manual identification of fourteen control points. In order to express the positional accuracy of the generated 3D surface models, the NSSDA guidelines were applied. Simultaneously acquired terrestrial laser scanning data – which had been processed in our standard workflow – was used to independently check the results. The vertical accuracy of the surface models generated by SfM was found to be within 0.04 m at the 95 % confidence interval, whereas several visual assessments proved a very high horizontal positional accuracy as well.
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paper_title: Low-Cost and Open-Source Solutions for Automated Image Orientation – A Critical Overview

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The recent developments in automated image processing for 3D reconstruction purposes have led to the diffusion of low-cost and open-source solutions which can be nowadays used by everyone to produce 3D models. The level of automation is so high that many solutions are black-boxes with poor repeatability and low reliability. The article presents an investigation of automated image orientation packages in order to clarify potentialities and performances when dealing with large and complex datasets.
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Title: Critical Factors and Guidelines for 3D Surveying and Modelling in Cultural Heritage

Section 1: Introduction
Description 1: Introduce the importance of 3D digital documentation in archaeology and cultural heritage, including the different types of survey techniques and their advantages.

Section 2: The 3D Digitization Pipeline
Description 2: Describe the steps involved in the 3D digitization process, from site examination to data acquisition and processing, emphasizing the key steps often skipped by non-experts.

Section 3: Test Sites and Objects
Description 3: Provide an overview of the five case studies used to illustrate the practical application of the 3D digitization pipeline on different movable and unmovable heritage objects.

Section 4: The Byzantine walls of Aquileia
Description 4: Detail the specific case study of the Byzantine walls of Aquileia, including the project's scope, constraints, and selected 3D recording techniques.

Section 5: San Galgano abbey
Description 5: Describe the case study involving the San Galgano abbey, focusing on the goals, constraints, and the 3D digitization method used.

Section 6: The etruscan Bartoccini's tomb
Description 6: Explain the 3D digitization of the Etruscan Bartoccini's tomb, covering the project's objective, constraints, and the specific surveying and modeling techniques implemented.

Section 7: The bronze statue of the Archangel Gabriel
Description 7: Highlight the 3D digitization project of the Archangel Gabriel statue, including the intricacies and constraints faced during the process.

Section 8: Archaeological museum objects
Description 8: Discuss various archaeological objects from the museum in Milan, illustrating the differences in 3D digitization methods based on the type and material of objects.

Section 9: Conclusions
Description 9: Summarize the overall conclusions, emphasizing the importance of combining photogrammetry and laser scanning, the need for interdisciplinary collaboration, and discussing the current challenges and future perspectives in the field of 3D digitization.