F Fermi National Accelerator Laboratory
`
`FERMILAB-Conf-97/081
`
`Open Inventor and Virtual Reality at Fermilab
`
`Amber Boehnlein, Jeff Kallenbach and Paul Lebrun
`
`Fermi National Accelerator Laboratory
`P.O. Box 500, Batavia, Illinois 60510
`
`April 1997
`
`Presented at CHEP, Berlin, Germany
`
`Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy
`
`MEDIATEK, Ex. 1023, Page 1
`IPR2018-00101
`
`

`

`Disclaimer
`
`This report was prepared as an account of work sponsored by an agency of the United States
`
`Government. Neither the United States Government nor any agency thereof, nor any of
`
`their employees, makes any warranty, expressed or implied, or assumes any legal liability or
`
`responsibility for the accuracy, completeness, or usefulness of any information, apparatus,
`
`product, or process disclosed, or represents that its use would not infringe privately owned
`
`rights. Reference herein to any specic commercial product, process, or service by trade
`
`name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its
`
`endorsement, recommendation, or favoring by the United States Government or any agency
`
`thereof. The views and opinions of authors expressed herein do not necessarily state or reect
`
`those of the United States Government or any agency thereof.
`
`Approved for public release; further dissemination unlimited.
`
`Distribution
`
`MEDIATEK, Ex. 1023, Page 2
`IPR2018-00101
`
`

`

`OPEN INVENTOR AND VR AT FERMILAB
`
`Je Kallenbach, Amber Boehnlein, Paul Lebrun
`
`Fermi National Accelerator Laboratory
`P.O. Box 
`Batavia, IL USA 
`
`Abstract
`
`We discuss our experiences with Open Inventor and with basic tools and
`techniques of Virtual Reality, including some preliminary results from an im-
`mersive system.
`
` Introduction
`
`Fermilab Physics Analysis Tools Group has been investigating Scientic Visual-
`ization Sci-Vis tools and techniques for many years . Much of our graphical
`computing has involved the use of Open GLOGL. In the past , we investigated
`emerging Open GL based Sci-Vis kits such as IRIS Explorer , IBM Data Explorer,
`and Sci-An. Additionally, X-compliant OGL clones such as MESA and VOGL
`have appeared, making OGL based applications accessible from a basic desktop.
`Recently, object oriented languages such as C++ have gained acceptance within
`the HEP community.
`The object oriented paradigm seems particularly well suited for graphics. In
`this article we discuss our experience with the C++ Open Inventor tool kit, and
`our rst venture into Virtual Reality VR.
`
` Open Inventor
`
`Open Inventor OI is an object oriented graphics tool kit that combines a set of
`C++ classes for creating shapes and properties in a scene database of objects with
`an Open GL based rendering system. A strength of the Open Inventor tool kit is
`that the application programmer interacts directly with the objects in the scene
`database, rather than with the graphics elements. The Virtual Reality Modeling-
`Language VRML , the language used to write World Wide Web applications, is an
`extension to the OI le format and provides a convenient format for exchanging les.
`Originally an SGI IRIX product, OI is now available on all major UNIX avors and
`NT platforms . An application programming interface to OI provides the graphics
`portion of IRIS Explorer. Based on our experience with IRIS Explorer and Open
`GL, we have evaluated OI as a tool for creating event displays, and doing scientic
`visualization and begun to study its use in Virtual Reality for particle physics.
`A motivation for using OI came from some limitations we had observed in IRIS
`Explorer. Firstly, the Explorer application interface to OI objects was limited to the
`creation of objects.
`In particular, individual objects in the scene database could
`not be manipulated and modifying an object involved destroying and recreating
`the full scene database. Thus, many of the interactive features in the Explorer
`
`
`
`MEDIATEK, Ex. 1023, Page 3
`IPR2018-00101
`
`

`

`based displays were nice, but slow and memory intensive. In addition, unnecessary
`memory manipulation can lead to a lack of robustness in the application. Secondly,
`the Explorer geometry scene database and all other Explorer data is stored in
`shared memory, so that the same data can be accessed from multiple processes.
`Shared memory is not as easily extensible as ordinary virtual memory, eectively
`limiting the usage of Explorer on some systems. Following the advice of the NAG
`group, we started coding directly in OI. The Examiner Viewer class provides the
`same visualization functionality as the Explorer Render Module, with closer control
`over the displayed data, including picked items. Other DOE sites are having success
`merging Explorer and OI in application programs .
`Currently, our use of OI has strictly been on SGI platforms, however, we plan
`to investigate the implementations on other platforms. For X-terminal display, the
`MESA library can be used for rendering, however it is quite slow.
`
`. MCFAST
`
`MCFast  is a fast Monte Carlo program for performing detector design studies.
`The detector geometry is dened in a ASCII le and a graphical display of the
`detector subsystems is necessary to verify the geometry. In addition, the display of
`the particle traces is found to be a useful debugging tool. Several Explorer modules
`were written to provide this functionality . The MCFast display is being rewritten
`and extended using OI with a Motif-based graphical user interface. The application
`is designed to create a separate OI scene database for each of the MCFast entities.
`In the current implementation, a scene database can be created on user request for
`the particle traces, the hit calorimeter cells and the detector geometry. The scene
`databases are displayed in standard Inventor Xt Viewer classes and can be viewed
`individually or together. This gives the user the exibility of viewing the traces
`with or without the detector at the same time by using two dierent viewers. As
`with the Explorer application, the user can interact with the scene by picking an
`object in the viewer or through the GUI. Using OI directly, objects can be added
`or removed from the scene database quickly and easily without reproducing the
`entire scene. Additionally, symmetry in the detector system can be exploited by
`reusing objects which are identical in shape, but at a dierent position, leading to
`an ecent use of memory.
`The detector scene database uses the OI switch class to toggle between simple
`and complex representations of the detector . This allows the user to view to
`the individual planes of MCFast detectors or to represent the detectors as simple
`volumes. The user choses between these dierent representations either directly in
`the viewer or with the GUI. The user can also set the color, transparency and style
`of the detector representations.
`The calorimeter cell database is useful for verifying the parameterized shower
`implementation in MCFast. There are eta projections, phi projections and a full
` d view that can be combined with the comparable projections for the trace scene
`database. The calorimeter cell energy is mapped to color to give a visual represen-
`tation of the energy density in jets. The calorimeter display is being adapted for
`use in an educational exhibit at the Ledermann Science Center.
`
`
`
`MEDIATEK, Ex. 1023, Page 4
`IPR2018-00101
`
`

`

`. GEANT
`
`The Geant G project is another opportunity to test the exibility of OI. One of
`the primary goals of Geant is to provide the users with maximum exibility with
`respect to use on an arbitrary desktop. Hookups to the various desktop graphics
`systems, called graphics drivers, are being provided for Open GL and X Windows.
`We have written the G OI driver.
`The details of the Geant design are presented elsewhere . Simply stated, a
`Geant view consists of a Frame window, inside of which is a Scene a collection of
`geometrical components. The dierent components are assembled in a hierarchical
`structure by the geometry section of the program, and passed to the Visualization
`Manager, which sends them to the graphics driver. The data to be displayed is
`assembled in a hierarchical fashion, with a Scene at the top, and progressing down
`into geometrical entities.
`In the case of G OI driver, the frame" consists of an OI XtViewer class with
`a menu bar allowing similar functionality as ivview, the SGI OI le viewer but ex-
`tending the capability to write out an ASCII Inventor le. The basic properties of
`the Viewer panel allow, without writing any code, rotation, zoompan, and switch-
`ing between various display modes e.g. solid and wireframe. Assembly of the
`geometry data into a Scene database is straightforward due to the similarities in
`the structures between G and OI data.
`The HEPVIS class libraries provided the next level of interaction to the G
`Scene. HEPVIS classes were developed for all of the basic G solids. By subclass-
`ing the HEPVIS classes, and constructing the scene using the subclasses, we have
`provided the capability to peel o" components, and to select and modify them.
`Again, much of this capability is provided by OI classes: the Xt Material Editor is
`used to edit the color and transparency properties of the selected component.
`
`.
`
`Informal use of Open Inventor
`
`OI is an ideal prototyping and debugging tool. At the early stage of an HEP exper-
`iments, such as the proposed BTeV experiment at Fermilab  or the Muon Collider
`project, exibility and ease of use are essential when designing tracking detectors
`and pattern recognition schemes. Visualization for these projects has been easily
`and eectively done using OI.
`
` Virtual Reality VR
`
`Advanced graphics has always been an essential tool at the design stage of HEP
`detectors. Besides the modeling of the engineering aspects of these detectors, the
`physicist has to graphically express measurement quantities as well, such as pulse
`heights or time of ight. It is our goal to bring the physicist inside a D represen-
`tation of the detector apparatus as well as to oer eective scientic visualization
`of abstract data. To do this, we are exploring Virtual Reality equipment and tech-
`niques.
`
`
`
`MEDIATEK, Ex. 1023, Page 5
`IPR2018-00101
`
`

`

` . Equipment
`
`To make an immersive" VR system involves connecting a costly display unit to
`high-end graphical workstation. We did a study of a few basic Virtual Reality
`systems, including projector systems, head-mounted BOOM devices, and desktop
`systems. In F.Y. , we purchased a desktop BOOM unit from FakeSpace, Inc .
`This unit provides an immersive environment right on the user’s desktop at some-
`what less cost than the projector-based units. This has been connected to an SGI
`R based Reality Engine through a multi-channel output board. We expect
`over time to expand our system to other types of display, such as high quality video
`projection systems. In this way, we will create a laboratory for VR studies.
`
` . Software
`
` D immersive systems are a distinct quantum leap away from constraints imposed
`by a D monitor.
`It would be a mistake not to establish bridges between the
`work using desktop technologies and advanced rendering made available through
`VR hardware. In particular, we want to avoid using a dierent graphical system
`to take advantage of the VR system as is used on the desktop. Such conversion of
`the graphics model could take longer than solving the problem using conventional
`graphics. Thus, compatibility with OI and VRML is necessary for the VR system.
`FakeSpace provides VLIB, a library of Open GL-based utilities and drivers for their
`hardware. VLIB is also capable to read OI les with minor changes. Note that
`computer aided design applications CAD can generate VRML les.
`
` Conclusions and The Future
`
`Open Inventor is a powerful, extensible and exible high-level object oriented toolkit.
`We have found it to be well documented and easy to use. It has support in the
`graphics community and has been ported to non-SGI platforms. The le format
`has become a de facto standard for graphics les, and has been extended to VRML
`for WWW use. Open Inventor can provide the basis for the desktop graphics our
`needs. We plan to investigate its use on other computing platforms.
`We still have insucient experience to declare whether or not Virtual Reality
`can be cost-eective and useful for HEP. We anticipate shortly that we will involve
`engineers and physicists in the VR project, and that they will be able to use the
`system to perform -D manipulation of particle detector components using their
`own input les and intuitive interaction with the system. The Open Inventor and
`VRML software systems are a good starting point for VR studies.
`
`References
`
` . J Kallenbach, P. Lebrun,Aspects Of Scientic Visualization For HEP Analysis
`at Fermilab, Proceedings of the International Conference on Computing in
`High Energy Physics ’ , Ed. R. Shellard, T. Nguyen, World Scientic, .
`. Open GL is a registered trademark of Silicon Graphics, Inc.
`
`
`
`MEDIATEK, Ex. 1023, Page 6
`IPR2018-00101
`
`

`

` . IRIS ExplorerT M was originally written by Silicon Graphics, Inc. and is now
`available through the Numerical Algorithms Group NAG consortium.
`. Data ExplorerT M is a trademark of IBM.
`. E. Pepke et al SciAn Scientic Visualization System, c. - , Florida
`State University
`. Open InventorT M is a trademark of Silicon Graphics, Inc.
`. MESA Graphics Libraries - Copyright -  Brian Paul, are available at
`iris.ssec.wisc.edu: ftppubMesa
`. E. Echidna A Very Ordinary GL Like Library, c. , , University of
`Melbourne
` . Connect to
`http:www.sdsc.eduSDSCPartnersvrmlsoftwarebrowsers.html
` . Template Graphics Systems http:www.tgs.com
` . E. Thornton, Batelle Pacic Northwest Laboratory, private conversation
` . R. Kutschke, these proceedings.
` . J. Boudreau, The HEPVis class library, these procedings
` . J. Allison, Geant Visualization Package, these procedings
` . Connect to http:fnsimu .fnal.govbtev.html
` . J. Boudreau, Unix. of Pittsburgh, A Tracking Class Library with built-in -D
`Visualization - http:fnpspa.fnal.govworkshoptalksboudreaupage .html
` . HEPVIS , Workshop on Visualization in HEP -
`http:axcn .cern.chhepvis.html
` . Connect to http:www.fakespace.com
`
`
`
`MEDIATEK, Ex. 1023, Page 7
`IPR2018-00101
`
`