Flight Simulator as Geospatial Visualisation Platform
John Hildebrandt (POC) DSTO C3 Research Centre Fernhill Park Department of Defence Canberra ACT 2600 Australia Phone: (02) Fax: (02) Email: john.Hildebrandt@dsto.defence.gov.au Daryl Bossert Royal Australian Air Force Department of Defence Australia
Abstract The use of 3D visualizations is increasing in Defence applications. However the cost of high-end visualization tools still limit the extent of their deployment. In this paper a common commercial flight simulator package is adapted for use in terrain visualization, situation displays and as a low cost simulation engine. A JAVA application has been developed to ingest military geospatial formats and convert these into a format usable by the flight simulator package. Multiplayer interfaces within the flight simulator package have been leveraged to allow extraction of track information into simulation systems and ingest of track information to support the generation of 3D situation displays.
Introduction The planning and execution of military operations involves the visualization of geospatial data. For example, the terrain appreciation process will benefit from terrain visualization, and situation displays typically use some form of geospatial display. The use of 3D visualizations and displays are increasing as they give the user a fuller representation of the battle space. However high-end 3D visualization packages can often be expensive assets that restrict their use to specialized areas. The game industry is now one of the key drivers in the development of 3D visualizations and these products are provided at mass market cost levels. Further the performance of commodity PC graphics hardware now offers performance levels previously only available in high-end 3D workstations and these performance levels are improving at an exponential rate. In this paper we report on our experiences in adapting a commercial off the shelf (COTS) 3D visualization tool, namely Microsoft Flight Simulator 2000 to visualize terrain and geospatial information. This has the potential to deliver a very low cost 3D geospatial visualization capability, which fully
exploits commodity PC graphics engines, for situations where high-end capabilities are not required or unaffordable. We have developed software to ingest military geospatial formats [CIB], [DTED] and convert this data into a form usable by Flight Simulator. This JAVA software allows the user to select CIB and DTED level 1 data of a region and then converts this into the terrain format used by Flight Simulator 2000 (FS2000). Other commercial software can perform similar conversions for a single image and terrain datasets [TERRABUILDER], however our software takes a full CIB dataset that consists of multiple images and generates a dataset covering the full region covered by these images. The use of the FS2000 platform to visualize simulated platform locations and to output simulated platform locations was investigated. This allows the tool to provide a low-end 3D situation display and inject data into other simulation systems. An XML output format was employed to facilitate connection to multiple applications. In the future connection to standard simulation protocols such as DIS and HLA is planned. In enterprise settings it is likely that the imagery and geospatial information will be obtained via libraries or repositories. In the future we intend to investigate ways to link the data transformation software to back end data repositories to simplify the steps the user must take to generate 3D terrain visualization.
Flight Simulator 2000 and DirectX Microsoft Flight Simulator 2000 is a commercial off the shelf flight simulator for Windows PCs developed for the entertainment market. It provides a worldwide terrain database and a collection of aircraft types for use in simulation. Although it is designed and marketed primarily for the entertainment area the software has been used as an adjunct to other commercial and military training programs. An instance of flight simulator can be designated as a game server and then other instances of flight simulator can connect to it. This allows multiple players to fly within the same simulated world. A variety of software developer kits (SDK) are available for Microsoft Flight Simulator [MSSDK] to support adding terrain information, developing custom aircraft, and to support multi player interfaces. These interfaces were essential for interfacing to Flight Simulator in this work and were the reason it was chosen over other commercial simulator packages. Currently the SDKs available include the following: Adventure Programming Language SDK Used for building lessons and scenarios. Multiplayer SDK Used to connect into the products Multiplayer Infrastructure. Aircraft Container SDK Used to design aircraft exteriors. Panels SDK Used to design internal aircraft control panel layouts.

Terrain SDK Used to ingest Digital Elevation data. Scenery SDK Contains details on adding data to scenery files.
Microsoft Flight Simulator is built on the DirectX libraries. DirectX provides a 3D graphics library supported by most graphics card manufacturers and in addition provides libraries for sound, multimedia, and multiplayer collaboration. The multiplayer features of Flight Simulator are provided via the DirectX multiplayer interface that is referred to as DirectPlay. The DirectX libraries will also be supported in the future X-Box gaming console that would offer an even lower cost option for deploying low cost visualations and simulations.
Other systems Several other systems exist for providing terrain displays for example we have examined higher end tools such as Autometrics BattleScape [BAT] and ERDAS VirtualGIS [ERDAS] to provide 3D terrain visualization. While these tools provide greater functionality we thought it was useful to examine how far a common low cost tool could be taken. The Virtual Terrain Project (VTP) [VTP] are providing free tools for terrain visualization so would offer good support for the visualization component of this work but does not address the simulation aspects. Open source flight simulator tools are also becoming available and would provide full access to source code for customization purposes.
Data Ingest Client The FS2000 terrain and scenery software developer kits (SDK) provided information on the formats used in FS2000 to describe terrain information. Terrain in Flight simulator 2000 is described using a scenery description assembly language that is then compiled into a binary format for use by the software. The scenery description includes height information for tiles on the Earths surface and descriptions of any objects within the world. To support draping of image textures over terrain the scenery file includes file name references to bit map files. An extract of a scenery file showing a reference to a texture file and embedded terrain height information is shown in figure 1.
Header(1 -8.976982 -9.046036 126.049861 125.975069) LatRange( -9.046036 -8.976982) set( areamx 64 ) GRP( -9.046036 125.975069 ) Area(B -8.988491 125.987535 60) PerspectiveCall(:L000001) Jump(:L000000) :L000001 Perspective RefPoint( 2 :L000002 1.000000 -9.000000 125.975069 v1= 0 v2= 0 E= 0.000000) SurfaceColor( ) Smoothing( 1 ) Bitmap( db000000.bmp ) BitmapMode( 0 ) TexRelief( 120; -9.000000 125.0 146; -9.000000 125.0 178; -9.000000 125.0 129; -9.000000 125.0 112; -9.000000 125.0 142; -9.000000 125.0 132; -9.000000 125.0 156; -9.000000 125.0 92; -9.000000 126.31 137; -8.997123 125.975069

Figure 1:

Scenery file (.sca) extract.
Our source of terrain information was Digital Terrain Elevation Data (DTED) that provides terrain heights over a spatial grid. It was important to be able to use this format to enable the use of data from military geospatial information (MGI) producing agencies. To provide a realistic 3D view we overlaid overhead imagery of the region onto the terrain surface. One source of imagery that we addressed was the Controlled Image Base (CIB) imagery that is produced by combining several satellite scenes of a region into a multi file standard product. So the task required was to transform the DTED and CIB data into the formats required by the FS2000 application. To achieve this we developed a JAVA application that allowed input of any image format supported by the JAVA Advanced Imaging (JAI) libraries and would output bitmap (BMP) formatted image tiles as required by FS2000. The DTED data and the coverage region of the supplied imagery were combined to generate the scenery description file that included references to the bitmap texture files. This file was then compiled to the binary format required by FS2000. Compilers for Microsoft scenery files are available from a variety of sources on the web. Importantly this application could convert a complete CIB dataset that consisted of multiple images in one session without user intervention. This was the main driver leading us to develop our own application rather than using commercial transformation tools. This process is an example of a data transformation process where to use a collection of data one must transform the data between various formats. Such transformations are common where a variety of imagery and geospatial products are in use. These
transformations can become a burden for the end user and in the longer term we would seek to automate the production of the data in the required formats.
Outputting track information To access positional information from a linked set of flight simulator packages a C++ application that links to the flight simulator server using the DirectPlay interfaces was developed. This application connected to the FS2000 server and extracted the navigational information for all aircraft registered with the server. The information was then packaged in an XML format and broadcast for use by other applications. Each XML message included an aircraft identifier, position and other information as available from the DirectPlay infrastructure. In the future outputting to some standard simulation protocol such as IEEE DIS could be implemented. Simple web based map display clients were developed which connected to the XML stream and displayed aircraft positions in 2D and 3D. In the future it is intended to use standard situation displays via the support for the required interfaces.

Inputting track information Once one is connected to the Flight Simulator server via DirectPlay one can also inject navigational information for other entities. This allows us to use the package to visualize tracks of other objects in 3D space. Again an XML format for the track information is employed to facilitate simple connection to other systems, but in the future a standard DIS connection could also be implemented. By identifying the entity as an aircraft type known to the FS2000 application it will then render a representation of the aircraft at the indicated position. To display abstract track symbols a special purpose aircraft type could be defined using the aircraft construction SDK. The operation of inputting and outputting track information is illustrated in figure 2. FS2000 Clients

XML reflector

Other Applications

FS2000 Server Figure 2:

DirectPlay to XML Process Exchanging DirectPlay position data with other applications.
Future Work The experiments with Microsoft flight simulator 2000 (FS2000) have proved that a low cost package can provide useful terrain visualizations on commodity hardware. In this work a JAVA application was developed that took CIB imagery and DTED level 1 data as input and output data files compatible with FS2000. This is an example of the need for a service that will take datasets of some formats and transform those into data formats required by some over application or service. In a large enterprise system the imagery and geospatial information will be stored in managed repositories rather than requiring knowledge of the file systems location of the data. The next logical step in developing the FS2000 capability is to demonstrate it as an example Data Transformation service that provides a direct link to Imagery and Geospatial services to source data for conversion into the files required by FS2000. One could envisage a web based application that allows the user to select the region of the world they are interested in. Then the service would connect to the image and geospatial service to obtain imagery and DTED data of the area and convert it into the FS2000 files. The files would then be placed at some location for use in FS2000. A further enhancement to a transformation service to a file would be to provide on the fly access to the data services from the client application. In the case of Flight Simulator this is difficult due to the lack of an on the fly API to obtain terrain data. However a partially dynamic solution could be provided in the following manner. One of the FS2000 files describes the terrain domain for a session and is loaded up front. As this is loaded at application startup it must be precompiled. Since it contains terrain height information this means all the DTED data is required up front. This file also lists the file names for the texture files that are generated from the imagery, so the file names must be determined up front. However the actual image texture files could be generated on an as required basis. This would require the system to keep track of the position one is at in the world and then use this to direct the population of the image texture files in a cache file system that FS2000 is directed to. To obtain the position information the multi-player features and API of FS2000 would be leveraged. If a large number of image tiles are involved a cache management system would be required to delete least recently used tiles as the cache file system is filled. The approach used here could be used to provide data transformation services to support other client applications. Particularly those that dont provide API access for data. This could lead to a family of data transformation services targeted at multiple applications and scenarios.

Conclusions In this paper we have shown how a low cost simulation package can be leveraged to obtain significant visualization and simulation capability at very low cost. While the capability will not match fidelity or flexibility of high-end tools it would be useful to provide limited capabilities to a much wider audience. For example the high cost of
many visualization tools in the past has limited their use to specialist cells within an organization. The availability of a low cost option would allow deployment of some capability to all users that could take advantage of it.
Bibliography BAT Autometrics Battlescape web site. http://www.autometric.com/AUTO/PRODUCTS/EDGE/BScape.html
CIB Controlled Image Base: Military Standard MIL-PRF-89041, available at NIMA web site, http://164.214.2.59/publications/specs/index.html. DTED Digital Terrain Elevation Data: Military Standard MIL-PRF-89020A, available at NIMA web site, http://164.214.2.59/publications/specs/index.html. ERDAS ERDAS Web Site http://www.erdas.com/
MSSDK Flight Simulator SDKs http://www.microsoft.com/games/fs2000/devdesk_sdk_fs2000.asp TERRABUILDER VTP http://www.terrabuilder.com/ http://vterrain.org/

Virtual Terrain Project

Testing the Hardware
You can test your Flight Sim Yoke and the gameport its using with the JCENTER test program included on the Flight Sim Yoke CD or diskette. It can be run directly from the CD or floppy in Windows 95/98 or DOS. Follow these steps: 1. To test your gameport in Windows: Click on: Start> Programs> CH Products> Flight Sim Yoke PC> Jcenter. To test in DOS mode: Click Start, Shut down, and select the Restart the computer in MS-DOS mode option, then click Yes. Insert the Flight Sim Yoke CD or diskette into your drive. At the DOS prompt (C:\), type: d:\jcenter [Enter] [where d is the letter of your drive]. 2. A blue screen will appear with a table on the left displaying a set of numbers. These numbers indicate the yokes current position. Compare your results with those in JCENTER Results: below.

FLIGHT SIM YOKE

QUICK START: HOW TO INSTALL THE CH FLIGHT SIM YOKE PC
Congratulations on your purchase of the CH Flight Sim Yoke! We are confident that you will find it to be one of the most precise and durable flight yoke controllers available. The CH Flight Sim Yoke PC is a snap to setup for your favorite DOS or Windows 95/98 flight games or simulators. It was carefully designed and manufactured in the U.S.A. by real aviation enthusiasts, so strap yourself in and get ready to experience a whole new level of simulation realism!
Figure 2. Typical JCENTER Readings (numbers will vary)
JOYSTICK A X 132 (Ailerons) Y 133 (Elevators) JOYSTICK B X NONE (Rudders if applicable) Y 224 (Throttle)
As you move the yoke the numbers under JOY A-X and A-Y should change. As you move the throttle the number under JOY B-Y should change. As you press the fire buttons and P.O.V. (hat) switch, the BTN 1-4s should light up on screen. (For more information, see JCENTER Results below).

Contents of the Box

One CH Flight Sim Yoke PC (IBM compatible gameport version) Two Clamping Arms and Two Bolts One CD or Floppy Diskette One Quick Start Sheet (this piece of paper)
JCENTER Results: If test displays numbers over 400 when the yoke is centered. Your gameport is too slow for your computer. You may need to install a faster game card such as the CH Gamecard 3 Automatic (sold separately). If test displays NONE under each axis in the table Your gameport is not enabled. If youve never connected a joystick into this computer before, chances are the gameport on the back of the computer has never been activated. No joystick will work until this is done. Many computer systems are sold without their gameports turned on. See your computers documentation or contact the manufacturer for information on how to enable the gameport.

Overview

Throttle Control Push Buttons (Buttons 7 & 8) Trigger/Mic. Button (Button 1) Rocker Trim Switch #2 (Buttons 9 &10) 4-way Hat Switch (Point of View)

Technical Support

To get the most efficient support, we recommend that you do a little research on your computer system so you can have answers ready for the questions the technicians may ask you. Please write down answers to the following questions before you contact us: What kind of computer do you have? How many/what kind of gameport(s) does your system have? With which programs (specifically) are you having problems? Do you have any other controllers (i.e. throttles, gamepads) plugged in? You can contact CH Products Technical Support at any of the areas listed below. Mailing Address: CH Products 970 Park Center Dr. Vista, CA 92083 Web site: Tech Support form (best): www.chproducts.com www.chproducts.com/support/form Fax number: Voice number: 760.598.2524 760.598.7833
Rocker Trim Switch #1 (Buttons 3 & 4) Gear & Flaps Toggle Switches (Buttons 2, 5, & 6) Desk clamps install into the yoke base and attach to your desk for a secure flight.
Elevator Trim Wheel (On Base)
CH Flight Sim Yoke PC Installation

Hardware Installation

Warranty
The CH Flight Sim Yoke is warranted to the original purchaser to be free from defects in materials and workmanship for a period of three (3) years from the date of purchase. During this warranty period, CH PRODUCTS will, at its option, repair or replace, at no charge, any component determined to be defective. The liability under this warranty is limited to the repair of and/or replacement of the defect or defective part at our factory, and does not include shipping expenses. This warranty does not apply if, in the opinion of CH PRODUCTS, the Flight Sim Yoke has been damaged by accident, abuse, improper usage, or as a result of service or modification by other than CH PRODUCTS. "NO OTHER WARRANTIES ARE EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF SALABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CH PRODUCTS IS NOT RESPONSIBLE FOR CONSEQUENTIAL DAMAGES." SOME STATES DO NOT ALLOW EXCLUSION OR LIMITATION OF INCIDENTICAL OR CONSEQUENTIAL DAMAGES, SO THE ABOVE LIMITATION OR EXCLUSION MAY NOT APPLY TO YOU. This warranty gives you specific legal rights, and you may also have other rights which vary from state to state. To obtain warranty services, send the Flight Sim Yoke, postage prepaid, with a check for $6.00 to cover shipping and handling, together with a dated proof of purchase and RMA# (Return Merchandise Authorization) obtained from CH PRODUCTS at 760.598.7833 to: CH PRODUCTS, 970 Park Center Dr., Vista, CA 92083. The enclosed software is made available as is, and without warranties of any kind. All warranty claims made on CH PRODUCTS relating to defects which may be present are expressly excluded where this is legally permissible. CH PRODUCTS assumes no liability for the correctness, precision, or currency of the software or of its accompanying documentation, nor for the suitability of the software for a specific purpose or for normal market quality. The risk relating to usability of the running characteristics of the software and the accompanying hardware lies with the user of the software. CH PRODUCTS shall not be liable for the performance of the software or for its functional capability in a multiple users association. The user shall bear the costs for correction of defects, costs for maintenance, repair or improvement work and not CH PRODUCTS, its dealers, distributors, representatives or employees.

4. 1. 2. 3.

Turn the computer OFF. Attach the Flight Sim Yoke to the edge of a flat table using the provided desk clamps. Simply slide the clamp arms into the base and then screw the bolts into the clamps. Tighten the clamp knobs until secure. Do not over-tighten! Plug the Flight Sim Yokes 15-pin connector into the gameport on your computer. If your gamecard has two ports, only use the primary one (sometimes labeled A). Pedal and Throttle Users: If you have a separate throttle controller or rudder pedals system, plug them into the computers primary gameport first, then plug your Flight Sim Yokes 15-pin connector into the throttle or pedals joystick port Turn the computer on and follow the directions below.
Software Installation (Windows 95/98 only)
Insert the provided 3.5 diskette or CD into the drive of your computer. Click Start, Run, and type: X:setup Enter [where X is the letter of your drive]. Select Install Drivers then select Flight Sim Yoke PC and follow the directions.

PN: 800-427 rev. 2.0

Windows 95/98, 2000, and MS-DOS are registered trademarks of the Microsoft Corporation 2000 by CH Products

Windows 95/98 Setup

After the Flight Sim Yoke driver has been installed (see Installation Software), you must configure and calibrate the yoke in the Windows 95/98 Game Controllers Control Panel. To set the correct driver in Windows 95/98: 1. Single Click on Start, Settings, and Control Panel. 2. Make sure that the general tab is empty of all controllers, then click on Add 3. From the list, select CH Flight Sim Yoke PC (win95) or CH Flight Sim Yoke PC (win98). Note: If you are running version Direct X 7.0 or later, place a checkmark in the rudder/pedals checkbox in this area. 4. Single click on OK To calibrate your CH Flight Sim Yoke PC: 1. Highlight the CH Flight Sim Yoke PC in your game controllers list and single click on Properties 2. Single click on the Settings tab. 3. Single click on Calibrate 4. Follow the onscreen instructions carefully. How to calibrate your CH Flight Sim Yoke PC (step by step):
Calibration is one thing you should repeat every time you plan to use your yoke. A good calibration can go a long way in giving you the control you expect while flying your simulator. 1. First, center the trim wheel on the base of the FSY, then jiggle the yoke handle and let it come to rest and press button 1 (trigger) on the left handle. Note: Each time you press a button you will advance to the next step in the calibration, so be careful. Click on back if you make a mistake. 2. Fully but gently, move the yoke to all extremes (in, out, left, and right) holding the yoke at each extent for a second or two. Four times around the box is generally enough, then press button 1 (trigger) on the left handle to advance to the next step. Note: During calibration the + may not go full range, this is normal. 3. Let the handle come to rest and press button 1 again to confirm the center position. 4. You are now ready to calibrate the throttle. Move the throttle handle forward and back, at least twice, slowly and completely. Then, press button 1 to advance to the next step. Note: It is normal for the red bar to not reach the top or bottom. When you test the controller after calibration it will work correctly. 5. Press enter on the keyboard four times to capture the P.O.V. (Point of View) hat. The arrow should move to all four directions. Then, press button one to complete the calibration. 6. Click on Finish, Apply, then OK. 7. After you have finished calibration, click on Test. Test all the buttons and movement. All movement and centering should now be correct. If any part of the test looks incorrect, calibrate the yoke again carefully. You are now ready to fly your favorite Windows 95/98 simulator! Note: Be aware that some games also have their own setup options within the game. If you have problems check the troubleshooting section or open the Flight Sim Yoke PC Help file for detailed information.

Products> Flight Sim Yoke PC> GamingCenter. Once Gaming Center is open, click on Help for instructions on how to use it. Click on the X to exit Gaming Center. Remember, Gaming Center is generally used with games that do not have built in joystick button remapping. If you can assign the buttons to do certain functions in your game then it is best to use the games utility, and not Gaming Center. Check with your games instruction manual for more information on assigning specific functions to your buttons.

Troubleshooting

I cant enable the Flight Sim Yoke in any games. Make sure that the Flight Sim Yoke is securely plugged into the primary gameport and that the gameport is enabled. You can check this by using a joystick test program such as JCENTER (see Testing the Hardware). If OK, make sure that youve correctly activated and calibrated the yoke within the game according to the manufacturer. Windows users, make sure that Flight Sim Yoke PC is listed as controller ID 1 in Game Controllers (Advanced tab). My Flight Sim Yoke wont center up correctly or drifts in the game. It is not properly calibrated. Re-calibrate the joystick in the game as well as in Windows Game Controllers. Before calibrating, make sure that the computer is warmed up (let it run a few minutes) and the yokes trim wheel is centered. During calibration, move the controls slowly and fully to the desired positions. Be sure to follow all directions carefully. If the Flight Sim Yoke still does not correctly calibrate, make sure the gameport in your system is fast enough for your computer by testing it in JCENTER (see Testing the Hardware). Remember, the yoke itself will not have a true center point. Therefore, your crosshair in the calibration test will not always be perfectly centered. My Flight Sim Yoke works in Windows 95/98 but doesnt in true DOS games. Your gameport is either 1) not enabled for DOS mode, 2) too slow for your DOS game, or 3) not setup in the game correctly. Some gameports require special setup in order to work in true DOS mode though they work fine in Windows 95/98. Also, many DOS games require a faster gameport for accurate joystick functionality. Check your gameport as described in Testing the Hardware. Enable or replace it as necessary. If it tests OK, make sure that you have activated the joystick in the game correctly as described by the games manufacturer. The Windows 95/98 control panel does not have a Game Controllers icon, or I cant select a joystick within the Game Controllers control panel. This usually means your system is not setup correctly and there is nothing wrong with your Flight Yoke or its software. What has happened is; 1) your gameport was not setup correctly when it was installed or 2) someone has deleted the Windows gameport driver. In either case, you must contact your soundcard/gamecard manufacturer for more information on reinstalling the gameport drivers that are damaged. Check your manuals for more information. Gaming Center does not work. When I program my buttons in Gaming Center they are completely ignored by my game. You will only be able to use Gaming Center with games that support Direct X 5 joystick inputs. Many games support Direct X 5 video and sound protocols but still use Direct X 3 joystick inputs for backwards compatibility. Check with your game manufacturer for more information. Remember, you may also have the ability to reprogram the buttons within your game, which is usually the better option in terms of compatibility. Check with your games instruction manual or technical support for more information.

Windows 2000 Setup

1. Single Click on Start, Settings, and Control Panel. 2. Make sure that the general tab is empty of all controllers, then click on Add 3. From the list, select 6-button joystick w/two POVs and throttle 4. Single click on OK Calibration is performed the same as Windows 95/98. Refer to the instructions above for more information.

MS-DOS Setup

There is no special driver required for DOS-based games, just make sure that the game supports a joystick or yoke. To enable the Flight Sim Yoke in a DOS game (even those that can be launched from within Windows), you must first setup and calibrate it within the game. Though joystick setup procedures vary from game to game, you can usually do it from the games Controls or Options menu. For more information, please see the games user manual. MS-DOS games that can be launched from Windows 95/98 still use their own built-in joystick drivers and thus will require setup within the actual game.
Gaming Center (Button Programming Software)
Gaming Center allows you to map your Flight Sim yoke buttons to keyboard functions for almost all of your Windows 95/98 games. To open Gaming Center, click Start> Programs> CH