March 2, 2004

Design Review: Laser Scanning Advances

Airports, hospitals, bridges, manufacturing plants, offshore platforms – all capital projects of any size undergo rigorous design review. Laser scanning holds promise of being a valuable tool for aligning client expectations with contractor deliverables – except today there’s no good way to bring point clouds into the visualization software used in design walkthroughs. But a race is on to deliver solutions, spurred by contractors and owners impatient for better answers.“The problem with CAD viewers,” one contractor reports, “is you can only work with the graphic component models – the CAD models. We’ve always said, ‘Wouldn’t it be nice to do walkthroughs of the point cloud model in the same way, bringing both sources of data – CAD and point clouds – into a dynamic walkthrough environment?’”

“The primary purpose would be to review with a client the existing conditions in relation to the new design,” this contractor explains. “When we do client reviews, the client says, ‘We want this here or there.’ But right now you don’t have the existing-conditions data so you could immediately see clashes” and other problems. “And it also becomes an issue of constructability. Once we have this new design, what do we have to dismantle or take out in order to put in the new work? What’s the installation sequence, what’s the timing sequence? Being able to see
existing conditions in conjunction with new work in a dynamic walkthrough environment would make all that much easier.”More productive design reviews

The problem is that leading point-cloud management applications communicate with CAD systems, but not directly with CAD viewers. For example, BitWyse’s LASERGen displays volumetric models of point clouds in MicroStation by intercepting view control commands in the CAD environment and interlacing these commands with its own view calls. But practitioners versed in the technology report that Bentley’s plant-related viewing tools use a different graphics engine than the MicroStation graphics system with which LASERGen interacts. Thus, the only way to bring laser scan data into the Bentley viewer is to first convert it to DGN geometry.

A further difficulty, according to another contractor, is the absence of any bridge between point-cloud data and the viewers of several leading plant design systems. With Intergraph Process, Power and Offshore’s PDS, “their viewer is a standalone application in that it’s not MicroStation-applications for working with point clouds in MicroStation, the graphics platform for PDS, “don’t work with either [Intergraph’s] legacy viewer or their newer SmartPlant viewer at the moment.” As for AVEVA’s PDMS,
“without any support at all for point cloud modeling at the moment, there is no solution.” Intergraph and AVEVA have reported to Spar Point that they are developing strategies to support point-cloud data in
SmartPlant and PDMS respectively.

A limited degree of walkthrough-like functionality can be had with CAD systems, though this is far from ideal. After using a point-cloud application to project a “static view of points into the CAD environment,”
as one practitioner describes it, “you can rotate the point cloud by rotating your view in the CAD environment – the point cloud will rotate in conjunction with the CAD model. The problem is that the CAD environment controlling the view is not dynamic.” Trying to use CAD view control commands for design reviews is “very awkward. That’s why viewers were created – to do walkthroughs” with a more natural set of user controls.Virtual-reality technology the answer?

The lack of effective walkthrough tools that can handle both point clouds and CAD data is not surprising in light of the technical difficulties. One challenge is streaming and rendering very large point-cloud datasets in real time. One contractor we spoke to believes that whatever solution emerges will probably be based on virtual-reality technology, because of its “ability to move in real time through detailed models.” He explains, “Whatever tool they use, borrowed from VR, will have to use level-of-detail reduction, probably taking the polygonal model and culling out whatever is not being viewed.” Still others believe this approach is doomed for large models at least because the computational burden
drives performance unacceptably low.

Also challenging, of course, is to bring the two kinds of data – CAD and require technology that can “render the CAD model in real time, and superimpose the point data interleaved to the correct depth. It’s comparatively easy to bring together two MicroStation models and resolve the depthing issues. Likewise, in a CAD environment, BitWyse and Cyra can bring CAD and laser data together by intercepting the view stream and fooling the eye. But there is not yet that openness in the design review tool that would let the point-cloud vendor intercept the viewing commands and repaint the screen with the two data streams interleaved.”Race to deliver

“It’s now a race between vendors,” as one contractor put it. “It comes down to who has the ability to manage the data in large volumes, and also be able to display it in large volumes.” Several kinds of solution provider are pursuing the opportunity, with varying degrees of enthusiasm. Design system vendors may eventually upgrade their viewers to handle point clouds, but today most are still working out their strategy for integrating point clouds with CAD, never mind the viewer.

Among point-cloud software companies, we’ve had firsthand accounts of development in this area. We believe those that have proven adept at integrating existing-conditions data with CAD systems are likely to do equally well with CAD viewers, given time. On the other hand, none has yet delivered, and many face constrained development resources – plus the antagonism that a really successful viewer could cause the CAD companies they have to work with.

A third choice comprises specialty developers of visualization and data streaming software such as TORNADO Technologies, Inc., RealityWave, Inc., VRcontext and the CADView-3D business line of Oracle (based on patents and intellectual property acquired from Assentive Solutions, Inc.,
formerly i-Engineer and Vuent). Of these, today TORNADO appears to be furthest ahead in delivering real-time visualization and streaming of point-cloud data. Web|VIZ Suite, its intranet/extranet offering for
collaborative 3D visualization, supports point-cloud data from 
Trimble/MENSI as well as a wide range of CAD data and standard data exchange formats. One contractor we interviewed noted that “a difference between TORNADO and the CAD viewers is that TORNADO is trying to address multiple CAD design formats in a single viewing environment.” Also appealing to this company are TORNADO’s prices compared with typical CAD viewer licenses. Further, “the CAD viewers require client software, whereas TORNADO can be entirely Web-hosted.” Finally, “TORNADO is shipping today.”

But the race is far from over. We believe the winning solution – whoever delivers it – will be one that:
• Works with data from any scanner and any CAD system• Does not require existing-conditions data to be decimated or segmented
• Lets users navigate a scene in real time without advance programming or intensive preprocessing
• Requires no client software beyond a web browser
• Doesn’t cost a bundle

This material is excerpted from Spar Point’s just-released publication
Capturing Existing Conditions with Terrestrial Laser Scanning: A Report on Opportunities, Challenges and Best Practices for Owners, Operators, Engineering/Construction Contractors and Surveyors of Built Assets and Civil Infrastructure

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