GPU ray casting method for visualizing 3D pipelines in a virtual globe

Pipelines are an important part of urban infrastructure development. As part of a virtual globe (VG), the high-efficiency and high-quality visualization of 3D large-scale and high-density urban pipelines is of great importance. This paper proposes a GPU-based pipeline ray casting method for the visualization of urban-scale pipelines in the framework of a VG. The method involves the initial partitioning of the pipeline data into tiles, based on the relationship between the pipeline layer scale and the discrete global grid system (DGGSs). The pipeline centerline in each tile is then segmented and encoded, and a coarser pipeline bounding volume is subsequently constructed using a geometry shader. Finally, the fine 3D pipeline is rendered using a pixel shader. The results of the experimental implementation of the proposed method show that it satisfies the requirements for the multiscale visualization of pipelines in a VG. Moreover, compared with the traditional polygon-based method, the method facilitates a 20% increase in rendering frame rate for the same pixel level accuracy display effect. It also enables the visualization of the thickness of the 3D pipeline without any obvious effect on the rendering efficiency

Remote Collaborative BIM-based Mixed Reality Approach for Supporting Facilities Management Field Tasks

Facilities Management (FM) day-to-day tasks require suitable methods to facilitate work orders and improve performance by better collaboration between the office and the field. Building Information Modeling (BIM) provides opportunities to support collaboration and to improve the efficiency of Computerized Maintenance Management Systems (CMMSs) by sharing building information between different applications/users throughout the lifecycle of the facility. However, manual retrieval of building element information can be challenging and time consuming for field workers during FM operations. Mixed Reality (MR) is a visualization technique that can be used to improve the visual perception of the facility by superimposing 3D virtual objects and textual information on top of the view of real-world building objects. The objectives of this research are: (1) investigating an automated method to capture and record task-related data (e.g., defects) with respect to a georeferenced BIM model and share them directly with the remote office based on the field worker point of view in mobile situations; (2) investigating the potential of using MR, BIM, and sensory data for FM tasks to provide improved visualization and perception that satisfy the needs of the facility manager at the office and the field workers with less visual and mental disturbance; and (3) developing an effective method for interactive visual collaboration to improve FM field tasks. This research discusses the development of a collaborative BIM-based MR approach to support facilities field tasks. The research framework integrates multisource facilities information, BIM models, and hybrid tracking in an MR-based setting to retrieve information based on time (e.g., inspection schedule) and the location of the field worker, visualize inspection and maintenance operations, and support remote collaboration and visual communication between the field worker and the manager at the office. The field worker uses an Augmented Reality (AR) application installed on his/her tablet. The manager at the office uses an Immersive Augmented Virtuality (IAV) application installed on a desktop computer. Based on the field worker location, as well as the inspection or maintenance schedule, the field worker is assigned work orders and instructions from the office. Other sensory data (e.g., infrared thermography) can provide additional layers of information by augmenting the actual view of the field worker and supporting him/her in making effective decisions about existing and potential problems while communicating with the office in an Interactive Virtual Collaboration (IVC) mode. The contributions of this research are (1) developing a MR framework for facilities management which has a field AR module and an office IAV module. These modules can be used independently or combined using remote IVC, (2) developing visualization methods for MR including the virtual hatch and multilayer views to enhance visual depth and context perception, (3) developing methods for AR and IAV modeling including BIM-based data integration and customization suitable for each MR method, and (4) enhancing indoor tracking for AR FM systems by developing a hybrid tracking method. To investigate the applicability of the research method, a prototype system called Collaborative BIM-based Markerless Mixed Reality Facility Management System (CBIM3R-FMS) is developed and tested in a case study. The usability testing and validation show that the proposed methods have high potential to improve FM field tasks