A. General Information
- How does PPT work?
Optical sensors mounted on the perimeter track active Light Emitting Diode (LED) targets. As the LED targets make their way through the room, the sensors acquire data. Through rapid processing, the sensors' data are converted to the accurate three-dimensional location of the markers. This data is transmitted by one of many methods to another computer that requires the tracking data.
- Will PPT work for my application?
As long as the workspace meets a few basic requirements, your PPT system will deliver high quality tracking data. Correct lighting and line of sight for at least two cameras are required for PPT to track targets.
PPT requires "cool" lighting, and does not like "warm" lighting. The terms warm and cool refer to the color spectrum that is typically associated with the lighting: blues and whites for cool, and reds and oranges for warm. Cool light source examples include fluorescent lighting, high pressure sodium, mercury vapor, and LED lighting. Warm light source examples include halogen flashlights and lamps, incandescent flashlights and lamps, sunlight, and candlelight.
PPT is an optical tracking system that calculates the 3D position coordinates of an LED target. To acquire the data, two or more PPT sensors need to simultaneously "see" the target. As long as the camera view of the target is maintained, you have satisfied the line-of-sight requirement mentioned earlier.
- Which tracking system is right for me?
PPT systems are recommended if:
A) goal is to track a large area with walking and interaction
B) goal is an 'easy to use' system for virtual reality interaction (like head and hand tracking for walking/looking around and grabbing objects and moving them around)
C) goal is a 'plug-and-play' integration with 'Live Characters', i.e. subject to see self-representation with a virtual body in the simulation
D) goal is to maintain a tight budget for tracking but still need a system for virtual reality interaction in a room or in front of a large screen
Electromagnetic/Magnetic systems like Polhemus or Ascension are recommended if:
A) goal is to track a small volume less than 6 feet (i.e. above a table)
B) objects to be tracked will occlude any optical line-of-sight to a camera
Motion Capture systems like Vicon, Motion Analysis, PhaseSpace, Xsens, Animazoo, etc. are recommended if:
Goal is Motion Capture (i.e. many points all over the body) for film and animation or within Vizard. Vizard works well with the Xsens "Moven" product.
Such systems can be useful if the goal is to do real-time ergonomics studies or interactivity studies with several people interacting in a VR space with full body motion capture.
- Where is the PPT manual
The PPT manual is a help file contained in the Start menu, under WorldViz, PPT Studio 2008 and is also available from the help menu when running the PPT Studio 2008 software.
- How do I set up the PPT?
Please contact WorldViz at support@worldviz.com if you have questions after reading through the manual included with PPT Studio 2008. Alternately, WorldViz may be hired to perform on-site installations.
- What hardware and software do I need?
All PPT systems are supplied with a computer running Windows XP 32-bit, and configured to be ready to use. There is no need to adjust any of the settings on this computer. PPT can provide tracking data by local Shared Memory, a serial RS-232 cable, and VRPN 6 and VRPN 7 over Ethernet. VRPN 7 over Ethernet is the recommended connection protocol.
- Can I connect over VRPN?
Yes. PPT systems are compatible with VRPN 6 and VRPN 7 protocols. See the PPT manual for further instructions.
- How long does it take to set up PPT?
About an hour for most users learning to set up PPT for the first time.
- How long does it take to callibrate PPT?
Between 30 seconds and 1 minute. The user places down a calibration rig which allows the cameras to quickly calculate their position in the tracked space.
- How much does a PPT system cost?
PPT ranges from $11,990 to over $40,000, depending on the type of PPT system, the number and resolution of the cameras, whether you purchase Vizard 3D VR Toolkit , and what other equipment you purchase to go with your hardware.
- Can I upgrade from one system to another?
You can upgrade from a 2 to 4, and 4 to 8 camera PPTX system. PPTH can have anywhere up to 32, but most systems are sold starting with 4 cameras.
- What can I use a PPT system for?
Motion Capture
PPT is capable of capturing up to 8 unique points when using MarkerID. A plugin has been written which allows the human form of a head, two hands, and two feet, to be tracked using MarkerID Targets. To use this feature, start your PPT Studio 2008 Software and enable the Post-Process plugin called MarkerID, then enable the Output plugin called MotionBuilder7.5. You will need a license for LiveCharacters (from WorldViz) and a license for MotionBuilder (from AutoDesk). For further instructions, please see the PPT manual.
PPT-H is a superior device for tracking mocap style movements because of the greater resolution/precision/accuracy and also because the data capture rate is almost three times as fast.
To properly implement Mocap related tracking, WorldViz recommends using 8 or more cameras to minimize the number of occlusions.
High speed tracking
The PPT-X and PPT-H systems operate at different frequencies of data capture. PPT-X captures data at 60 times per second, or, every 16.6 milliseconds. The PPT-X captures data at 175 times per second, or, every 5.7 milliseconds.
For fast moving models, or work that needs many more data points, faster tracking is crucial. A golf swing is an example of a fast movement. If analyzed with a PPT-H system the information gathered will be much more significant than with a PPT-X system because there will be more data points gathered in the swing.
Multiple Participants
Multiple participants can walk around a shared space using either the PPT-X or PPT-H. The PPT-H is our preferred system, capable of faster update rates and finer resolution of points in an area. Because there is onboard preprocessing performed on the PPT-H sensors, processing load is removed from the PPT-H main computer which allows the system to track more markers with more cameras. Keep in mind that points can swap unless using MarkerID targets. When using PPT-H, swapping will be less likely to occur, and if a target is lost due to occlusion the reacquisition will be much faster with a PPT-H system.
Tool use
Vizard can make use of virtual reality tool models that are linked to sensor data. Position and orientation can be controlled by using a number of different types of trackers, and USB, button boards, or serial interfaces can be programmed to receive real tool manipulation data to effect corresponding visual changes in the virtual tool, which can be used to manipulate a virtual object. Components to make this possible would be: Vizard, 6DOF tracking (optical, inertial, magnetic, or a combination), 3D model of the tool, a method of representing location of tool, and an interface method if necessary (button, switch, etc).
PPT systems are excellent for providing position data for this application.
Programming can become complicated, and WorldViz offers custom programming. See our price list for more details.
Tracking user(s)
VR users can be tracked by optical, inertial, or magnetic tracking systems. Some optical trackers are passive (reflective markers), while others are active (light emitting markers, usually LEDs). A user's head, hands, feet, or all of these can be tracked.
If the goal is to track a person over a large space at an economical price while delivering high resolution position and orientation data, our PPT system for position and inertial orientation sensors are ideal. PPT can track a person's whole body for simple motion capture, but not with the high fidelity that a dedicated but more expensive motion capture system can offer.
In order to track a person's whole body for motion capture, several companies have developed optical, inertial, and magnetic tracking systems. We can speak to you about the strengths and weaknesses of each type of technology. Please contact us for further information and to help you choose a system appropriate for your needs.
Tracking an object(s) for study
PPT can track objects with very high resolution at economical prices over very large areas. PPT can also track objects with ultra high resolution (i.e. less than .25mm) if tracking in small areas like 10x10 foot spaces. Whatever the size of your space, if the goal is to know the precise location and orientation of an object, PPT is likely the best tracking system for your needs.
Virtual Fly-Thru for CGI cinematography applications
Many companies are currently offering cinematography "Fly-Through" hardware systems that allow for fly-thru paths to be captured and the pathway, speed, and orientation to be saved and exported to an editing program of your choice. With Vizard and PPT-H, you can overlay the virtual camera's field of view on the scene as you move, and make adjustments, path smoothing, and orientation adjustments in your software post-capture. WorldViz software can show low fidelity mockups of your scene and you can literally hold and guide a virtual camera's view in real time, and then watch the playback instantaneously. This a very economical way to add flythrough capabilities to a large CGI landscape, capturing your audiences perspective in the palm of your hand.
- What is PPT is not good for:
PPT for face tracking
Face tracking is best done with a system designed for face tracking. These track many points, and PPT systems do not track large point clouds at such close distances.
PPT for outdoor applications
PPT is not meant for outdoor applications that will be exposed to sunlight, which would interfere with the LED markers. Note that PPT will work outdoors at night since there is no interference from the environment.
PPT as standalone optical 6DOF tracking
Because PPT is a system that focuses on real time tracking in large areas, we do not rely on "rigid body" point clouds to identify the orientation of a point. Instead, we utilize a Hybrid approach that incorporates both 3DOF position and 3DOF orientation tracking. Orientation is provided by inertial sensors, and position is provided by the Precision Position Tracking system (PPT).
However, PPT does have a "rigid body" plugin, which can use multiple markers to calculate orientation in simple scenarios. Refer to the PPT user manual for configuration instructions.
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B. Technical Questions
- PPT as 6 DoF system?
6 Degree of Freedom (DoF) Tracking refers to three axes of position and three axes of orientation. X,Y,Z, and yaw, pitch, roll. Together, these six axes can define the position and orientation of a point. A point can be associated with a head, hand, etc. In the virtual world the point will correctly align the view of the Virtual Environment with your head, place your hand in the correct orientation and position at your side or in front of you.
Because PPT is a system that focuses on real time tracking in large areas, we do not rely on "rigid body" point clouds to identify the orientation of a point, which have a limited range. Instead, we utilize a Hybrid approach that incorporates both 3DOF position and 3DOF orientation tracking. Orientation is provided by inertial sensors, and position is provided by the Precision Position Tracking system, PPT.
However, PPT does have a "rigid body" plugin, which can use multiple markers to calculate orientation in simple scenarios. Refer to the PPT User Manual for configuration instructions.
- What is my maximum tracking area and how do I achieve it?
PPTX and 10x10x10 m tracking space:
To achieve a 10x10x10m tracking space with a PPT-X system, the cameras should be slightly outside of the 10x10x10m tracking zone. Our cameras have a specific field of view, and you must take into account that the cameras have to "see" the entire 10x10x10m area with at least two camera views overlapping at all points in order to track the entire space.
PPTH and 50x50x50m space:
Similar to the PPT-X system, it is important to make sure cameras are outside of the 50x50x50m space with at least one set of camera views overlapping in order to track the entire space.
- What is Marker ID?
Marker ID is used to differentiate one marker from another. PPTH is the most ideal system with which to use MarkerID, however it is possible to use MarkerID Targets with PPTX as well. Because PPTX is a 60Hz system, not a 175Hz system, the MarkerID units are sampled almost 1/3 fewer times per second, meaning there are fewer datapoints recorded per second, or per unit of measure if the marker is moving.
- Can I do full body motion capture with PPT?
Many companies produce full body motion capture products. PPT exists as a lower cost, equally high resolution, and much wider area tracker than some options on the market. PPT, however, is not made to go head to head with data-quality of the exact kinematic data of the subject being tracked.
When you need full body motion, our new PPT Mocap feature can be used to produce smooth full body motion using as few as 5 body markers. Compared to other traditional full body motion capture solutions, ours requires significantly less setup and calibration. Combined with Live Characters, you have a truly low-cost powerful real-time digital human capture system.
- How do I add orientation to my PPT system?
Hybrid optical/inertial tracking with Intersense and Xsens
PPT Studio 2008 can connect to multiple Intersense and Xsens sensors and tie the data to a particular PPT wireless marker. In this way, data returned by PPT is true 6DoF position & orientation data and is ready for use by any compatible application.
Specify the port of your Intersense Tracker, and a PPT light number to associate the tracker with, and you will be using the WorldViz recommended 6DoF tracking solution. You can use MarkerID lights to maintain positive identification of your marker at all times if multiple targets are in use.
PPTeyes: For Multi-Wall-Projection-Screens
Given two PPT wireless markers (3DOF data only), this plug-in will compute the 5DOF position and orientation solution necessary for driving a CAVE-like stereo projection system (recommended for CAVEs & Powerwalls).
Just specify the separation of the markers and the desired tolerance, and click ok. You can purchase a pre-built CAVEyes from WorldViz, or alternatively build your own.
Optical Heading: accounting for magnetic interference
This plugin uses 2 PPT marker lights to correct for magnetic distortions present in a tracking space. A specialized filter is used to preserve the smoothness of the sensor device, while using the overall accuracy of the markers to remove errors.
The two LED markers can be affixed to any separation device, usually either a dowel rod composed of wood or a composite material. This plugin is designed to augment another magnetic tracker that is experiencing distortions due to magnetic interference. Configure the plugin with your marker separation, tolerance, and percentage you would like the plugin to influence your magnetic tracker's values. A value of 100% would completely take over your magnetic tracker, while 0% uses no optical information at all.
- What are the specifications for PPTX and PPTH?
|
Edition
|
PPT X
|
PPT H
|
|
Sensor
|
CCD
|
CMOS
|
|
Maximum Number Of Targets
|
8
|
32*
|
|
Maximum Number of Cameras
|
8
|
32*
|
| Maximum Camera Range |
15 m ** (60 Hz)
|
20 m (175 Hz)**
45 m (60 Hz)**
|
|
Suggested Tracking Space
|
10m x 10m x 10m
|
50m x 50m x 50m
|
|
Precision (3m x 3m x 3m volume)
|
< 1 mm
|
< 0.25 mm
|
|
Accuracy (3m x 3m x 3m volume)
|
< 0.5 cm
|
< 0.25 cm
|
| Horizontal Field Of View |
68 deg
|
79 deg
|
|
Update Rate
|
60 Hz
|
175 Hz
|
|
Image Processing
|
central CPU
|
within camera
|
|
Maximum Cable Length
|
75 m
|
100 m
|
|
Camera Interface
|
analog
|
digital
|
|
Processing Interface
|
RS-232, Ethernet
|
RS-232, Ethernet
|
|
Camera Size
|
160 x 70 x 60 mm
|
240 x 57 x 80 mm
|
|
Camera Weight
|
500 g
|
900 g
|
_ * Trade-off between maximum camera / target number. Ask for details.
_** For a marker to be tracked, it must be visible by two or more cameras. Overall tracking space
___dimensions are determined by the camera range, camera layout, and background lighting
- What is the maximum numbers of markers and cameras?
PPTX functions with up to 8 markers. These can be either MarkerID for unique identities, or standard Targets. PPTX functions with up to 8 Cameras, and additional configurations by contract only.
PPTH functions with up to 32 Cameras.
- What are the frequencies of the PPT systems and their significance?
The PPTX and PPTH systems operate at different frequencies of data capture. PPTX captures data at 60 times per second, or, every 16.6 milliseconds. The PPTX captures data at 175 times per second, or, every 5.7 milliseconds.
For fast moving models, or work that needs many more data points, faster tracking is crucial. A golf swing is an example of a fast movement...if analyzed with a PPTH system the information gathered will be much more significant than with a PPTX system because there will be more data points gathered in the swing.
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C. Common Packages
- What other hardware and software do I need?
When using a tracking system, an input output software platform capable of receiving the data and assigning it to an object is important. Our software toolkit, Vizard, is essentially that, with an extravagant lineup of additional features enabling you to realize even the most wild Virtual Reality concepts. Vizard is an indispensible software platform for your purposes. Try it out for free by downloading it from our website.
Next, think about the type of application for which you plan to use the tracking. Decide if you need data gloves, interaction wands, a cubical projection room or an HMD for viewing, MarkerID to maintain unique identities of different points, additional workstations for working with data, haptic force-feedback tools, 3D sound tools, overhead cable management systems for navigating large spaces in an HMD, and more.
A note about the data: Precision Point Tracking systems deliver 3DoF or 6DoF data. This data is processed in a software program that is capable of receiving VRPN 6 and 7 protocols which are used by a wide variety of 3D applications. If you wish to interface to PPT via an RS-232 interface, WorldViz provides sample source code for both Windows and Linux operating environments. In all cases, connecting to a PPT simply involves interfacing via serial RS-232 and accessing the data either in a streamed or polled manner.
- Tracking user(s)
VR users can be tracked by optical, inertial, or magnetic tracking systems. Some optical trackers are passive (reflective markers), while others are active (light emitting markers, usually LEDs). A user's head, hands, feet, or all of these can be tracked.
If the goal is to track a person over a large space at an economical price while delivering high resolution position and orientation data, our PPT system for position and inertial orientation sensors are ideal. PPT can track a person's whole body for simple motion capture, but not with the high fidelity that a dedicated but more expensive motion capture system can offer.
In order to track a person's whole body for motion capture, several companies have developed optical, inertial, and magnetic tracking systems. We can speak to you about the strengths and weaknesses of each type of technology. Please contact us for further information and to help you choose a system appropriate for your needs.
- Motion capturing with PPT
PPT is capable of capturing up to 8 unique points when using MarkerID. A plugin has been written which allows the human form of a head, two hands, and two feet, to be tracked using MarkerID Targets. To use this feature, start your PPT Studio 2008 Software and enable the Post-Process plugin called 5-point Mocap, then enable the Output plugin called MotionBuilder7.5. You will need a license for LiveCharacters (from WorldViz) and a license for MotionBuilder (from AutoDesk). For further instructions, please see the PPT manual.
PPTH is a superior device for tracking mocap style movements because of the greater resolution/precision/accuracy but because the data capture rate is almost three times as fast.
To properly implement Mocap related tracking, WorldViz recommends using an 8 or more camera system.
- High speed tracking with PPT
The PPTX and PPTH systems operate at different frequencies of data capture. PPTX captures data at 60 times per second, or, every 16.6 milliseconds. The PPTX captures data at 175 times per second, or, every 5.7 milliseconds.
For fast moving models, or work that needs many more data points, faster tracking is crucial. A golf swing is an example of a fast movement...if analyzed with a PPTH system the information gathered will be much more significant than with a PPTX system because there will be more data points gathered in the swing.
- Tracking multiple participants with PPT
Multiple participants can walk around a shared space using either the PPTX or PPTH. The PPTH is our preferred system, capable of faster update rates and finer resolution of points in an area. Keep in mind that points can swap unless using MarkerID Targets. When using PPTH, swapping will be less likely to occur and if a Target is lost due to occlusion, reacquisition will be much faster with a PPTH system.
VR users can be tracked by optical, inertial, or magnetic tracking systems. Some optical trackers are passive (reflective markers), while others are active (light emitting markers, usually LEDs). A user's head, hands, feet, or all of these can be tracked.
If the goal is to track a person over a large space at an economical price while delivering high resolution position and orientation data, our PPT system for position and inertial orientation sensors are ideal. PPT can track a person's whole body for simple motion capture, but not with the high fidelity that a dedicated motion capture system can offer.
In order to track a person's whole body for motion capture, several companies have developed optical, inertial, and magnetic tracking systems. We can speak to you about the strengths and weaknesses of each type of technology. Please contact us for further information.
- Tracking tools in a virtual world
Vizard can make use of virtual reality tool models that are linked to sensor data. Position and orientation can be controlled by using a number of different types of trackers, and USB, buttonboards, or serial interfaces can be programmed to receive real tool manipulation data to effect corresponding visual changes in the virtual tool, which can be used to manipulate a virtual object. Components to make this possible would be: Vizard, 6DOF tracking (optical, inertial, magnetic, or a combination), 3D model of tool, method of representing location of tool, interface method if necessary (button, switch, etc).
PPT systems are excellent for providing position data for this application.
Programming can become complicated, and WorldViz offers custom programming. See our pricelist for more details.
- Tracking an object(s) for studies
PPT can track objects with very high resolution at economical prices over very large areas. PPT can also track objects with ultra high resolution (i.e. less than .25mm) if tracking in small areas like 10x10 foot spaces. Whatever the size of your space, if the goal is to know the precise location and orientation of an object, PPT is likely the best tracking system for your needs. It is possible to place markers around a room to specify object locations.
- Virtual Fly-Thru for CGI cinematography applications
Many companies are currently offering cinematography "Fly-Through" hardware systems that allow for fly-thru paths to be captured and the pathway, speed, and orientation to be saved and exported to an editing program of your choice. With Vizard and PPTH, you can overlay the virtual camera's field of view on the scene as you move, and make adjustments, path smoothing, and orientation adjustments in your software post-capture. WorldViz software can show low fidelity mockups of your scene and you can literally hold and guide a virtual camera's view in real time, and then watch the playback instantaneously. This a very economical way to add flythrough capabilities to a large CGI landscape, capturing your audiences perspective in the palm of your hand.
D. Support
- 30 Day Money Back guarantee!
We offer a money back guarantee for a system returned in perfect condition.
- What does PPT support consist of?
All purchases of WorldViz hardware products include a 12 month warranty on all parts and 3 months of free priority
e-support and telephone support.
Priority e-support guarantees you'll have an answer within 1 business day. Very often, you actually have your answer in less than 4 hours.
Extended support contracts can be purchased.
If at any time during your support contract your system fails unexpectedly you can contact WorldViz for immediate support which will consist of a round of troubleshooting. If the problem is not fixed WorldViz will pay shipping costs for the transportation of the hardware back to our headquarters for testing and repair. All fees are waived for support holders whose equipment has failed due to a manufacturers defect.
- Can WorldViz guarantee up-time?
Guaranteed up-time is different from support because although fees will be waived, a contingency plan needs to be in place to keep the customer up and running in the event of failure. These support contracts are tailored to the customer's needs. Please inquire with your WorldViz sales person if you require guaranteed up-time.
- I dropped a camera and it seems to be damaged, what should I do now?
At this time WorldViz does not offer insurance for damage caused by users to their own equipment. It may be possible for a lab to purchase this type of comprehensive insurance independently. If damaged and not covered by your lab's/business's warranty, WorldViz sells replacement equipment.
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E. Using PPT (for those already using the system)
- How do I calibrate the system?
For an immediate overview, access the Help menu at the top of the PPT Studio 2008 screen. Calibration should be a straightforward procedure. First, lighting conditions need to be controlled. Second, all cameras should be able to see the included Calibration Rig and the point registering in the software side camera views. The Calibration Rig should be correctly oriented with Z+ pointed in the direction you want Virtual North to be. Start the calibration by clicking on the "calibrate" button.
- How do I enable a PPT Studio 2008 plugin?
For help with a particular function, access the Help menu at the top of the PPT Studio 2008 screen. PPT Studio 2008 has many plugins that are accessed on the Configuration menu on the left side of the Graphical User Interface. If you can't see this menu, turn on the Pane by accessing it in the View menu by clicking Panes, then clicking Configuration.
- How do I use the +/- marquis?
It is possible to remove bright spots from the camera views that are showing up as Tracking Targets by using the Tracking Area Adjustment + and - Marquis.
Clicking the + or - buttons and selecting the areas of interest will allow manual addition and subtraction of tracking area.
 The blank button will restore the entire tracking area.
 The last button will automatically remove bright spots from the processed camera view. Note that all markers should be turned off, or their locations will be removed.
- How do I talk with other hardware over VRPN?
Please search the PPT Help for "Talking to a host application or system", "Using PPT with other Applications", and "VRPN".
- PPT Output to TrackD
Please contact WorldViz at support@worldviz.com
- Maximizing PPT performance with Gain and Sensitivity settings
Please contact WorldViz at support@worldviz.com
- Setup and Operating Environment
Setup time for permanent positions
The steps included here are:
1. Mounting cameras to walls.
2. Running cables, either through ceilings, walls, conduit, or simply attaching them to walls with cable hangers.
3. Setting up computer.
4. Connecting all cables.
5. Optimizing camera settings and possibly changing environmental lighting conditions and calibrating.
It is likely that a standard permanent installation of a 4-camera PPT system will take one to two days working normal hours.3. Setting up computer
4. Connecting all cables
5. Optimizing camera settings and possibly changing environmental lighting conditions to exclude warm lighting sources and calibrating.
It is likely that a standard mobile installation of a 4-camera PPT will take approximately 2 hours.
During calibration, it is important for PPT to know which direction will end up being Virtual North. The Calibration Rig has a +Z axis that you should align with your desired "front" of your virtual environments. You will need to ensure that any Intersense or Xsens sensors you are using are also aligned to the same virtual north direction.
Setup time for mobile installations
The steps included here are:
1. Setting up tripods.
2. Running cables.
Lighting Limitations
PPT cameras can be set within the software to work in a range of environmental lighting conditions. Ideal lighting conditions consist of a room isolated from sunlight, lit only by fluorescent bulbs.
Alternate lighting conditions under which PPT will also be able to perform are high pressure sodium, LED, and mercury vapor. Because threshold sensitivity and gain can be adjusted on both the software and hardware sides, it is possible for PPT to function in the presence of very low levels of sunlight or incandescent penetration into the environment. "Hot spots" can also be cut out of the tracking view on the software side using the +/- Marquis.
Specify Virtual North
During calibration, it is important for PPT to know which direction will end up being Virtual North. The Calibration Rig has a +Z axis that you should align with your desired "front" of your virtual environments. You will need to ensure that any Intersense or Xsens sensors you are using are also aligned to the same virtual north direction.
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F. Details
- Operating Systems compatibility?
Any OS that can run VRPN is capable of communicating with PPT. PPT software only runs on the Windows platform, and is node locked to the machine that is supplied by WorldViz.
- Connecting to PPT
Precision Point Tracking systems (PPT) deliver 3DoF or 6DoF data. This data is processed in a software program that is capable of receiving VRPN 6 and 7 protocols which are used by a wide variety of 3D applications. If you wish to interface to PPT via an RS-232 interface, WorldViz provides sample source code for both Windows and Linux operating environments. In all cases, connecting to a PPT simply involves interfacing via serial RS-232 and accessing the data either in a streamed or polled manner.
- With cameras close together, what is the new position and accuracy?
When cameras have view angles that are as close to perpendicular as possible tracking accuracy will be the best. As cameras move closer to either parallel or 180 degrees facing each other, the ability to determine a 3D location by triangulation points becomes more difficult, and so errors will increase. If two cameras are mounted very closely to either parallel or 180 degrees facing each other, a 3D solution may not be possible.
- PPT Specification Sheet
|
Edition
|
PPT X
|
PPT H
|
|
Sensor
|
CCD
|
CMOS
|
|
Maximum Number Of Targets
|
8
|
32*
|
|
Maximum Number of Cameras
|
8
|
32*
|
| Maximum Camera Range |
15 m ** (60 Hz)
|
20 m (175 Hz)**
45 m (60 Hz)**
|
|
Suggested Tracking Space
|
10m x 10m x 10m
|
50m x 50m x 50m
|
|
Precision (3m x 3m x 3m volume)
|
< 1 mm
|
< 0.25 mm
|
|
Accuracy (3m x 3m x 3m volume)
|
< 0.5 cm
|
< 0.25 cm
|
| Horizontal Field Of View |
68 deg
|
79 deg
|
|
Update Rate
|
60 Hz
|
175 Hz
|
|
Image Processing
|
central CPU
|
within camera
|
|
Maximum Cable Length
|
75 m
|
100 m
|
|
Camera Interface
|
analog
|
digital
|
|
Processing Interface
|
RS-232, Ethernet
|
RS-232, Ethernet
|
|
Camera Size
|
160 x 70 x 60 mm
|
240 x 57 x 80 mm
|
|
Camera Weight
|
500 g
|
900 g
|
_ * Trade-off between maximum camera / target number. Ask for details.
_** For a marker to be tracked, it must be visible by two or more cameras. Overall tracking space
___dimensions are determined by the camera range, camera layout, and background lighting
G. Use Case
- Virtual Environment: 1 user, 1 marker, 1 orientation marker
A single user with one marker being tracked, and one orientation sensor, one ideal solution from our experience is to use:
- Vizard Development Edition software toolkit
- nVis MX60 HMD
- InterSense IC2
- High end Dell XPS computer with nVidia GeForce GTX280 by EVGA
- PPT-X4 or PPT-H Tracking system
- Fluorescent lighting
A user would be able to wear the HMD, mount a single Target to the HMD, mount the IC2 on the built -in mounting plate, and walk around a Virtual Environment.
The same user could hold the marker, mount the IC2 on the HMD, and stand stationary and model the Virtual Environment to allow the user to point the marker at interest areas to enable manual selections of Visual Content for review.
H. Questions or Comments?
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