In our paper we will present results of an on-going project connected with monitoring the condition of 12 fragments of the Museum of King Jan III’s Palace at Wilanów (Warsaw, Poland) building façade by 3D structured-light scanning method. During 30 months, 7 series of three-dimensional measurements have been planned. In each of the twelve elevation fragments, chosen by the conservation and architecture departments as particularly interesting, an area of 120 mm x 120 mm was scanned with 2500 points/mm2 resolution. This article describes the methodology of the measurement process, the hardware setup developed especially for this purpose, as well as the data processing path and analysis algorithms. In addition to having such accurate measurement data, we must still be able to match the measurements carried out in the same place at intervals of several months. For this purpose the areas of interest were marked with special aluminum targets, embedded with three intersecting planes. The algorithm of their detection, analysis and use for aligning data from subsequent measurement series is discussed. A portable SLS 3D-measurement head with two cameras, integrated with linear drive has been developed for scanning purposes and adopted to use in outdoor condition. The 3D scanner has a measurement volume limited to 45 mm x 50 mm x 10 mm for a single scan, due to high-resolution requirements. In less than 25 minutes, 40 measurements are acquired at various positions, covering the entire area, with the support of a controlled linear stage stand. Individual scans are pre-aligned with limited accuracy and then fitted using the Iterative Closest Point algorithm. The final representation of each fragment is a cloud of points with color containing more than 200 million 3D measurement points. We present the results of 3D measurements and a proposition of a monitoring procedure for assessing the change in 3D surfaces over time.
The pace of development of information systems nowadays demonstrates the magnitude of the demand for digitization of all aspects of our lives, such as medicine, industry, and documentation of cultural heritage. Digitization is the process of converting objects from the real world into their digital representations. In order to acquire complete and detailed information about the whole surface of an object, several 3D scans have to be taken from different perspectives. The resulting 3D object can be acquired in a form of a numerous amount of 3D point clouds overlaying each other. Sometimes, depending on a quality of a 3D scanner and surface properties, the point clouds can represent a noisy geometrical surface and an incorrect colour. Moreover, the directional point clouds are not perfectly aligned and a registration between them must be applied. The registration of the point clouds is a complex task which is not always possible to automate. Usually, the entire process of registration has to be supervised by a skilled operator. The registration is usually divided into two parts: initial and final matching. Initial matching is a more complex one and in this scenario, it is supported by the known system calibration, which includes, e.g., robotic arm, head of the scanner, sources of lights. Using ICP based algorithms afterward is usually enough to get appropriate final matching. The difficulty of point cloud registration increase accordingly to the number of directional clouds of points to integrate. The aim of this paper is to propose a methodology to decrease or even fully eliminate some of the presented registration issues encountered during the reconstruction of Museum of King Jan III’s Palace at Wilanów.
As forensic science technologies progress, digital photography in the crime scene documentation is being replaced in favor of high-precision 3D measurements. Three-dimensional documentation presents every object in the context of the entire crime scene and allows accurate measurements between potentially important traces, like bloodstains or weapons. These and other advanced 3D documentation and analysis tools have improved the possibilities of investigation to a previously unattainable level. We present a novel solution for detailed 3D documentation, which overcomes the limitations of commonly used 3D measurement techniques, e.g. highly accurate Structured Light Scanning or convenient to use Structure from Motion. Our solution, called active-SfM, involves the use of special projection devices to project a random pattern on the part of the scene under measurement. This modification makes the measurement process robust and reliable, even when measuring featureless surfaces. The reconstructed 3D model has better quality and surface uniformity than the result of standard Structure from Motion measurements. Moreover, the acquisition process remains as quick and easy to use as before the modifications.
We present newly developed equipment: wireless projection devices and controllers, that were designed especially to be used by forensic technicians on crime scenes and that are compatible with stock cameras used by them in everyday practice. We also present a full set of developed algorithms that transform input images into the final 3D model.
The proposed solution complements the hierarchical, three-dimensional measurement system developed in recent years by Polish Central Forensic Laboratory of the Police, CYBID Ltd., and Warsaw University of Technology, designed especially for crime scene documentation. The whole documentation process is supervised by a specialized CrimeView3D application, a software platform for measurement management and data visualization. We also present the outcome of measurement sessions that were conducted on both simulated and real crime scenes with the cooperation of Technicians from Central Forensic Laboratory of Police.
KEYWORDS: 3D scanning, Scanners, 3D metrology, Laser scanners, Blood, 3D modeling, 3D visualizations, Forensic science, Surveillance, Computing systems
Three dimensional measurements (such as photogrammetry, Time of Flight, Structure from Motion or Structured Light techniques) are becoming a standard in the crime scene documentation process. The usage of 3D measurement techniques provide an opportunity to prepare more insightful investigation and helps to show every trace in the context of the entire crime scene. In this paper we would like to present a hierarchical, three-dimensional measurement system that is designed for crime scenes documentation process. Our system reflects the actual standards in crime scene documentation process – it is designed to perform measurement in two stages. First stage of documentation, the most general, is prepared with a scanner with relatively low spatial resolution but also big measuring volume – it is used for the whole scene documentation. Second stage is much more detailed: high resolution but smaller size of measuring volume for areas that required more detailed approach. The documentation process is supervised by a specialised application CrimeView3D, that is a software platform for measurements management (connecting with scanners and carrying out measurements, automatic or semi-automatic data registration in the real time) and data visualisation (3D visualisation of documented scenes). It also provides a series of useful tools for forensic technicians: virtual measuring tape, searching for sources of blood spatter, virtual walk on the crime scene and many others. In this paper we present our measuring system and the developed software. We also provide an outcome from research on metrological validation of scanners that was performed according to VDI/VDE standard. We present a CrimeView3D – a software-platform that was developed to manage the crime scene documentation process. We also present an outcome from measurement sessions that were conducted on real crime scenes with cooperation with Technicians from Central Forensic Laboratory of Police.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.