CIMdata Publications
Visualizing Product Data
John MacKrell, Senior Consultant, CIMdata, August 2005
Product Lifecycle Management (PLM) provides access to all kinds of product development information throughout the product development process. Just making information available and easily found provides only part of the value that PLM offers. The greatest benefits of PLM accrue when the complete set of product information is made available to all types of people in the enterprise, including product designers, engineers, manufacturing engineers, management, marketers, maintenance personnel, sales, purchasing, and many others, from the time the information is first created until the product is retired from the market.
Leveraging value from information is not only an issue of allowing people to find what they need. It also entails communicating all information in a manner that people can make use of it and derive value from it while performing their tasks in the product development process. Historically, communication among product development teams has been done via verbal discussions and paper-based documents. However, this need to communicate information applies to all types of data—textual, 2D drawings and photographs, 3D designs, 3D analysis input and results, dynamic data (e.g., flow simulation, motion studies, ergonomic evaluations), product structures, product manufacturing information (PMI), and many other data formats and attributes. While 2D data, i.e., documents and drawings, may help convey certain types of information, it is not suitable for helping people understand and use the highly content rich data that defines and describes products in modern companies today. One of the most glaring examples of this problem is the heavy reliance product developers place on using 2D drawings to define complex products. The third and fourth dimensions of real products are typically ignored—for good reason—the 2D drawing and text paradigms just don’t support the representation of three-dimensional and time-based motions at all well and certainly not in an intuitively obvious manner. Manufacturing companies more and more have trouble hiring factory workers who know how to read technical drawings and even highly trained engineers and draftsmen can and do misread 2D drawings. Clearly, we need new ways to communicate and leverage product definition information. Especially because data communication is also the key to successful collaboration processes. Likewise, collaboration is a primary enabler of innovation; one of the major initiatives pursued by progressive organizations today. To collaborate, people must be able to find information, but they also must be able to see and evaluate that information. Leveraging the value of information-rich design information provides companies with the opportunity to speed products to market, improve quality, increase innovation, and reduce cost.
While you can use many different formats for data viewing, this leads to many issues, some not unlike those encountered when using multiple CAD solutions. First, when multiple formats are used, people usually have to have a number of different software tools to view and work with the data, leading to a proliferation of tools and increased maintenance and IT costs. Second, when data has to be kept in multiple formats, multiple files have to be maintained. This leads to a much higher potential for some data to become inconsistent and out of synch with the original data. When data is being used to do work within the product development process, many problems can arise from the use of outdated information, not limited to propagating errors and problems. People also have to learn how to use multiple tools. And confusion can arise when data in an incorrect format is sent to someone who can’t access it. All of these lead to increased costs and the high probability of increasing the number errors in the product development processes.
A number of formats are available that claim to be able to satisfy the needs of all users by allowing 3D data, and sometimes other data such as 2D drawings and documents, to be viewed from a fairly simple viewing tool. These include formats such as UGS’ JT, Dassault’s 3D XML, 3D Industry Forum’s (3DIF) U3D, Tech Soft’s HOOPS Stream, and Web 3D Consortium’s VRML and X3D, plus others. In addition, a number of companies provide viewing tools that use admittedly proprietary formats, such as Cimmetry, Actify, Spicer, and Informative Graphics. Given all of these choices and the number of claims made by the various vendors, how are you supposed to choose a primary viewing technology?
When choosing a format that will allow one, consistent mechanism for viewing all types of product design information within collaborative and interoperable product development processes, technical and business issues have to be considered within the context of how an extended enterprise needs to use product data and who needs to use that data within the extended enterprise. The technical and business issues are linked to the types of usage that need to be supported. Some of the key issues to be considered are described below.
Things to Consider
Usage Scenarios
Using product information to support the product development process to best advantage requires that companies develop a strategy that embraces the complete product lifecycle. It is tempting to consider using visualization tools as a point solution applied to only one or a few processes within product development, however, this minimizes its value because it does not take advantage of the potential of leveraging high-value data in other areas. Uses of product information abound. It can be used to support enterprise collaboration interoperability, The design process, change processes, manufacturing instructions, service and maintenance processes, in-field use, supply chain support, design and engineering, marketing, manufacturing, management, and many others.
How product information is to be used in an organization will drive the decision to adopt one data format over others. It is important to realize that there may not be one absolutely “correct” choice; that any of a number of the available choices may suite your organization. However, there are considerations, both technical and business, that should be taken into account as well.
Technical Issues
Many different capabilities are needed to some degree to support various uses of information. As users evaluate data formats and viewers, they need to understand and evaluate a number of technical issues based on the usage scenarios required to support their business requirements.
The breadth and depth of data coverage for documents, CAD, CAE and FEM, PMI, PDM, ECAD, and other types of attributes and data determines how well the visual data format can be used to support a broad range of users and usage scenarios. The more complete the data is, that is, its richness, the more different types people can take advantage of it in their work areas. Some viewable formats allow users to predetermine what parts and types of data are transmitted, helping protect proprietary information.
The compression ratio determines how much a viewable data file can be reduced in size. Smaller files can be transmitted more quickly through lower bandwidth communication systems (see the following figure). However, when files are compressed, the may loose some fidelity, becoming less accurate or less meaningful. The level of compression varies due to a number of factors that include the geometry used for the viewable data, the amount of data loss that is acceptable, and the desired fidelity of the compressed data to the original data (that is, the data accuracy retained). Some use cases, such as on-line sales catalogs, do not require high compression ratios.
The Interrelationship of Data Compression and Communication Bandwidth
Measurable accuracy is desirable in some cases. For some uses, such as shipping studies, low accuracy of measurements (say to the nearest millimeter) can be tolerated. For other use cases, such as using the viewable data during a design process, the accuracy may need to be equal to that found in CAD models. Some viewable formats are based on triangular tessellation of the surfaces of CAD designs. When this is done, the chordal deviation (or sagitta) of the planar triangles when compared to the original surface determines measurable accuracy. The smaller the triangles used, the closer they approximate the original geometry, but the larger the viewable data becomes. Accuracy that is good enough for one user may not be sufficient for other users so it is important that the viewable data files can be generated at user-specified fidelity. Boundary representations (B-reps) or surfaces may also be embedded in the viewable data file, providing CAD model measurable accuracy.
Data streaming is a set of techniques that build up a viewable display of data over time, starting with a rough, incomplete view, and refining the quality of the view until it is either completely detailed or the user moves their point of view. Traditionally, applications have needed to retrieve an entire data file before the user or the application could begin to see, access, or work with the data contained therein. This slows down work and can frustrate users. Streaming applications partially alleviate this issue by enabling access to the data before the entire file is downloaded. In order to maximize the effectiveness of a streaming application, data must be delivered in an order dependant on the user’s interaction. A streaming application determines what the user is viewing and sends data in an order that is specific to the user’s viewpoint. Some viewing formats can store multiple sets of data at various levels of fidelity to facilitate streaming the data to the user from the lowest resolution of data to the highest.
Most product definitions are assemblies of many parts. To be able to understand the structure of the overall design, the assembly or product structure relationships and configurations of the parts of the assembly must be available for users to navigate. When the data is to be used to perform digital mockup studies, this structure may need to be augmented with information that describes how parts move with respect to their connected parts.
Business Issues
Beyond the technical issues that determine how well a particular data format works, are the business issues surrounding the format’s program. These determine its viability as part of a long-term strategy for viewing, sharing, and collaborating on data throughout the product development process.
Free viewers tend to improve adoption of a technology, which drives its acceptance and long-term viability. While the free viewer may not have all of the capabilities an organization needs to support its business processes, they can be helpful in certain cases, such as when data needs to be published to people in the supply chain who do not have the wherewithal to buy special viewing tools.
The capabilities of most free viewers are fairly basic; for instance, they generally provide the user with the ability to rotate parts or assemblies, but lack precise measurement, cross sectioning, and assembly structure management commonly found in current commercial viewers. But they can be used quite satisfactorily under certain circumstances. For instance, for people who are basic consumers of information or for reviewers, the ability to peruse product data may be sufficient.
The adoption of the format by both end users and companies that create viewers and other data manipulation tools indicates if others believe that the format is viable.
Likewise, the number of integrations to CAD and other tools that generate viewable data (such as generalized drawing tools) can be used to gauge the breadth of the format’s applicability.
Finally, you will want to gauge the vision and maturity of the supplier as well. The length of time they have provided viewing tools and the number of years they have spent developing such technologies.
Summary and Conclusions
Of course there are many other issues that need to be considered, but the important thing is that you understand why your organization (including your extended enterprise of suppliers and customers) needs 3D data viewing and what benefits you expect to receive from it. You also need to develop a process for visual data sharing and collaboration—both for internal users and with your partners. Build a lifecycle story based on business needs, not just support for discreet events. As much as practical, adopt a consistent, common format, not separate formats for different users. And don’t forget PDM, you have to be able to manage the data and assure that people are always working with the most up-to-date and consistent data.