A system Architecture and Simulation Environment for Building Information Modeling in Virtual Worlds

3.1.BIM Simulation System Prototype Architecture

The diagram reflects the research team’s current understanding of client requirements for the prototype under development. It is expected that changes to the system’s architecture will occur as users add new requirements or modify the ways that components interact with one another. The processes and interactions between clients, design team, data bases, OLIVE and BIM are based on use cases developed to date. As additional use cases are explored, lessons will be incorporated into the software system, component design and into the system’s architecture.

3.2.OLIVE 2.4.0

Importing an object into OLIVE 2.4.0, illustrated here using a building, begins with the instantiation of a structure in Autodesk® Revit which is then exported to Autodesk® 3DS Max as a .fbx file. In Autodesk® 3DS Max, each object must be manually tagged according to a hierarchical taxonomy for grouping and coupling objects. It is also necessary to manually establish an object’s spatial references and geometric relationships between the imported object under consideration and other objects in OLIVE. These remain tedious, laborious and time consuming tasks.

Figure 3.2 below illustrates a basic building rendered by the research team in Autodesk® Revit which took the team several hours to import into OLIVE 2.4.0.



Figure 3.2. OLIVE 2.4.0 Building

Research and analysis to improve OLIVE 2.4.0 functionality across several areas was conducted by the team during the past year. This effort led to a number of recommendations being accepted as possible improvements to the processes outlined above and in OLIVE 3.0.

The team analyzed OLIVE’s collision mesh protocol that prevents avatars and other objects from passing through or colliding with each other or other objects. The collision mesh reference system uses up to 400 distinct vertices for rendering and positioning complex shapes [8]. Another research area was related to the level of detail (LOD) mesh used for rendering object appearances. Typically, BIM object features are specified as attributes developed in Autodesk® 3DS Max. The upper bound for the LOD mesh is approximately 8000 vertices which gives developers a significant range for attribute specification [8]; something that also significantly increases object attribute complexity. Although these remain manual processes, the team developed algorithms that simplified and streamlined the process of decomposing complex shapes into simpler objects with their own LODs and collision meshes.

Both the collision and LOD meshes must be parented to the master-root which serves as an invisible (to the user) dummy object to which object attributes are anchored within the taxonomy. This establishes a coordinate reference position relative to the master-root for each component that forms the object’s physical structure [8]. The specific attributes of each component, such as, materials, surfaces, textures and finishes must be assigned in Autodesk® 3DS Max because the direct draw surface (.dds) extension is not supported by Autodesk® Revit. This requires objects to be imported from Autodesk® 3DS Max into OLIVE as .om or .model formats using appropriate plugins. The team’s analysis of these areas led to development of new methods and guidelines for categorizing attributes and clarifying relationships between and among objects using Autodesk® 3DS Max. The research team’s new methods and processes streamlined the process of decomposing and incorporating complex objects into OLIVE.

3.3.OLIVE 3.0

As part of the joint SAIC-PKI research initiative, the research team undertook development of new OLIVE capabilities. Once the capabilities are fully developed and integrated into OLIVE 3.0, it will enable users to port objects from Autodesk® Revit into OLIVE without making the necessary intermediate adjustments or refinements in Autodesk® 3DS Max in order to port objects into the virtual world.

Figure 3.5 below illustrates a building ready to be exported into OLIVE 3.0 that the team instantiated in Autodesk® 3DS Max. It was rendered, including edits, in less than 30 minutes. This illustrates a potential significant improvement of OLIVE 3.0’s development environment over 2.4.0 where it took the team several hours to develop the same building.



Figure 3.5. OLIVE 3.0 Building

Finally, building OLIVE 3.0 on the Unity game engine platform makes it widely and easily available as a web application with only a web browser required to view, edit and develop objects in OLIVE 3.0. This overcomes user limitations and restrictions which slow object development in OLIVE 2.4.0.

4.results and findings

In working with the architectural and engineering communities and SAIC programmers, the team quickly found that the process of porting building information models into OLIVE 2.4.0 was far from ideal due to several factors. First, development time required for objects in Autodesk® 3DS Max is the most onerous and most difficult to overcome. Second, the burdensome requirement for OLIVE 2.4.0 files to be loaded onto user computers as a precursor to collaboration significantly limited participation during both synchronous and asynchronous work sessions. OLIVE 3.0, on the other hand, offers a much improved platform with its improved graphics, web-based access, and easy-to-use object development environment.

Although a mature capability for importing and editing objects during runtime is far from being fully developed in OLIVE 3.0, its potential to import a wide range of 3D models in varying formats and accompanying capability to rapidly develop, edit and modify object functionality and attributes such as position, size, rotation, material, and finishes of objects are significantly improved over 2.4.0. By way of illustration, two figures are presented below of a building rendered in OLIVE 2.4.0 and Unity to compare and contrast these differences. The building rendered in Unity will appear identical in OLIVE 3.0 when the system is fully integrated.

Figure 3.3 depicts outside and inside views, respectively, of a building created in OLIVE 2.4.0. It took the development team, which has become quite proficient at using OLIVE, approximately three hours to render the building in 2.4.0. From the illustrations, one can readily see the building’s lack of detail and texture which clearly illustrates a prominent shortcoming with OLIVE 2.4.0; namely, its inability to enhance object features to reflect user-desired functionality and level of detail.

In contrast, Figure 3.4 illustrates the same building developed in Unity which shows a much richer environment for developing and customizing objects. As compared to OLIVE 2.4.0, object resolution, quality of graphics, textures and finishes and enhancements to objects are much improved in OLIVE 3.0.

As mentioned, rendering a detailed OLIVE 2.4.0 object remains a tedious, manual process that requires system users to spend a significant amount of time and effort making enhancements in Autodesk® 3DS Max before a detailed object can be exported into OLIVE 2.4.0. Even a modest amount of detail for a simple building takes an experienced user several hours to organize the object’s attribute hierarchy, and to add features, materials and finishes. In OLIVE 3.0, on the other hand, it is possible to significantly reduce the time required to render the same object by up to 5-fold with much improved detail and graphics.

Other advantages of OLIVE 3.0 include the following:

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  The completed 3.0 toolkit will allow users to easily and quickly position objects in the virtual environment in relation to other objects enabling the user to rapidly transition to an immersive game environment;
  
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  3D objects developed or imported into 3.0 could be easily positioned in any 3.0 scene;
  
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  Other game objects such as lights, terrain and miscellaneous objects can be imported to enhance the quality of 3D buildings in the virtual environment in Unity and can be modified using the Unity editor;
  
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  Current OLIVE functionality such as mesh colliders that provide physical barriers which ‘attach’ to each object and supported file formats including those with the following extensions .fbx, .dae, and .obj are transferable from 2.4.0 to 3.0; and
  
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  A new graphical user interface (GUI) was developed by the team as part of this phase of research for easily and quickly changing the position, size, and rotation of any object or that is a sub-component of an existing object.