Civil Engineering Reference
In-Depth Information
8.3 Module implementations
Four modules are combined in the iHelmet - an information integration module,
positioning module, manipulation module and display module. The following
sections give detailed descriptions of each of these modules.
8.3.1 Information integration module
The information integration module retrieves building information from a BIM
model and integrates it into an image-basedmodel. Themain advantage of having
an image-based model is its efficiency in loading and displaying the model. The
efficiency depends on the total number of building elements: the more building
elements there are, the more random access memory (RAM) is required. The
memory problem is more apparent in a mobile device, where memory capacity is
usually smaller than that of a desktop computer. The image-based model displays
the building information as images, and only one image at a time. The efficiency of
loading and displaying, therefore, depends solely on the resolution and com-
pression format of the image, instead of the total number of building elements.
This image-based technique can greatly improve the efficiency of browsing
information.
In this research, Autodesk Revit was used to build our BIM model. This BIM
model includes floor plans, cross-sections and MEP details about various building
elements, such as pipe and rebars dimensions, or information on socket inserts.
Information was retrieved from this BIM model in image format and these images
integrated into an image-based model.
The procedure of information retrieval is shown in Figure 8.5. Firstly, the BIM
model was divided into floors and floor plans were retrieved from the BIMmodel in
image format. Secondly, each floor plan was divided into several view units by areas,
including rooms and common spaces. Public areas here included corridors and
lavatories. For each view unit, the floor plan was enlarged to fit the area, in order to
present it more clearly. Thirdly, detailed information about the view units was
retrieved from the BIM model, including information on doors, windows, floors,
walls, and other building elements. Users in a given view unit need only choose a
building element as a target to receive all the details about it. In this research, a wall
was used as an example and all detailed information about this wall retrieved,
including rebar, piping and electrical information. If the users choose this wall as
the target, they can browse the rebar plans, piping plans, and electrical plans of this
wall. Furthermore, they can browse the dimensions of the rebar, the pipes, and
information on the sockets.
8.3.2 Positioning module
The positioning module can specify the location of a user, which is an essential step
in providing location-based information. Figure 8.6 shows the procedure for
positioning. Firstly, users need to select a floor in order to obtain the floor
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