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== Ambient Lighting Frequency==
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== Capturing without eStrobes==
 
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When capturing high-speed videos, the brightness of the captured frames may vary depending on which type of ambient light source is used.
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When capturing without eStrobes, the camera entirely relies on the ambient lighting to capture the image, and the brightness of the captured frames may vary depending on which type of light source is used. In general, when capturing without an eStrobe, we recommend setting the camera at a lower framerate (30~120 FPS) and increasing the camera exposure to allow for longer exposure time so that the imager can take in more light.
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====Indoor====
 
====Indoor====
 
[[Image:ColorCam AmbientLight.gif|thumb|Incandescent light flickering. The video was captured at (121 FPS).]]
 
[[Image:ColorCam AmbientLight.gif|thumb|Incandescent light flickering. The video was captured at (121 FPS).]]
:When capturing indoors without the eStrobe, you will be relying on the ambient room lighting for brightening up the volume. It is important to note that every type of artificial light source illuminates, or flickers, at a certain frequency (e.g. fluorescent light bulbs typically flicker at 120Hz). This is usually fast enough so that the flickering is not noticeable to human eyes, however, with high-speed cameras, the flickering may become apparent.
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:When capturing indoors without the eStrobe, you will be relying on the room lighting for brightening up the volume. Here, it is important to note that every type of artificial light source illuminates, or flickers, at a certain frequency (e.g. fluorescent light bulbs typically flicker at 120Hz). This is usually fast enough so that the flickering is not noticeable to human eyes, however, with high-speed cameras, the flickering may become apparent.
  
 
:When Prime Color captures at a frame rate higher than the ambient illumination frequency, you will start noticing brightness changes between consecutive frames. This happens because, with mismatching frequencies, the cameras are exposing at different points of the illumination phase. For example, if you capture at 240FPS with 120Hz light bulbs lighting up the volume, brightness of captured images may be different in even and odd numbered frames throughout the capture. Please take this into consideration and provide appropriate lighting as needed.
 
:When Prime Color captures at a frame rate higher than the ambient illumination frequency, you will start noticing brightness changes between consecutive frames. This happens because, with mismatching frequencies, the cameras are exposing at different points of the illumination phase. For example, if you capture at 240FPS with 120Hz light bulbs lighting up the volume, brightness of captured images may be different in even and odd numbered frames throughout the capture. Please take this into consideration and provide appropriate lighting as needed.

Revision as of 11:43, 17 April 2018

Main PageActive Marker Tracking

Page Scope

This page provides instructions on how to set up, configure, and use the Prime Color video camera.

Overview


Prime Color

The Prime Color is a full-color video camera that is capable of recording synchronized high-speed and quality videos, and it can also be hooked up to a mocap system as a reference camera. The camera enables recording of high frame rate videos (up to 500 FPS at 480p) with resolutions up to 1080p (at 250 FPS) by performing onboard compression (H.264) of captured frames.
PrimeColor Overview PrimeC.png

eStrobe

When capturing high-speed videos, camera exposure times are very short, and providing sufficient lighting becomes critical in order to obtain clear images. The eStrobe is designed to optimally brighten the image taken by Prime Color camera. This is achieved by precisely synchronizing the illuminations of the eStrobe to each camera exposure. This capability allows the LEDs to illuminate at a right timing, producing the most efficient lighting for the high-speed video capture.
  • PrimeColor Overview eStrobe.png
  • PrimeColor Overview eStrobe2.png

Hardware Setup


Focus and F-Stop

A Prime Color camera can be equipped with either the 12mm F#1.8 lens or the 6mm F#1.6 lens. The 12mm lens is zoomed in more and is more suitable for capturing at long ranges. On the other hand, the 6mm lens has a larger field of view and is more suitable for capturing wide area. Both lenses have adjustable f-stop and focus settings, which can be optimized for different capture environments and applications.

  • F-Stop: Set the f-stop to a low value to make the aperture size bigger. This will allow in more light onto the imager, improving the image quality. However, this may also decrease the camera's depth of field, requiring the lens to be focused specifically on the target capture area.
  • Focus: For best image quality, make sure the lenses are focused on the target tracking area.

Info2.png

Note for 6mm F#1.6 lens: When capturing 1080p images with 6mm F#1.6 lens, you may see vignetting in each corner of the captured frames due to imager size limitations.

Load Balancing

Data Bandwidth

Before going into details of setting up a system with Prime Color cameras, it is important to go over the data bandwidth availability within the camera network. One Prime Color camera can transmit data at a rate of up to ~100 Megabytes-per-second (MBps), or ~800 Megabits-per-second (Mbps), at its maximum bit-rate setting for capturing the best quality image. In comparison, a tracking camera in Object Mode outputs data at a rate less than 1MBps, which is several magnitudes smaller than the output from a Prime Color camera. A standard network switch (1 Gb switch) and network card only support network traffic of up to 1000 Mbps (or 1 Gbps). When Prime Color camera(s) are used, they can take up a large portion, or all, of the available bandwidth, and for this reason, extra attention to bandwidth use will be needed when first setting up the system.
When there is not enough available bandwidth, captured 2D frames may drop out due to the data bottleneck. Thus, it is important to take the bandwidth consumption into account and make sure an appropriate set of network switches (PoE and Uplink), Ethernet cables, and a network card is used. If a 1-Gb network/uplink switch is used, then only one Prime Color camera can be used at its maximum bit-rate setting. If two or more Prime Color cameras need to be used, then either a 10-Gb network setup will be required OR the bit-rate setting will need to be turned down. A lower bit-rate will further compress the image with a tradeoff on the image quality, which may or may not be acceptable depending on the capture application.

Info2.png

Detecting Dropped 2D Frames

Every 2D frame drops are logged under the Status Log panel, and it can also be identified in the Devices pane. It will be indicated with a warning sign next to the corresponding camera. You may see a few frame drops when booting up the system or when switching between Live and Edit modes; however, this should only occur just momentarily. If the system continues to drop 2D frames, that indicates there is a problem with receiving the camera data. If this is happening with Prime Color cameras, try lowering down the bit-rate, and if the system stops dropping frames, that means there wasn’t enough bandwidth availability. To use the cameras in a higher bit-rate setting, you will need to properly balance out the load within the available network bandwidth.

Note: Due to the current architecture of our bug reporting in Motive, a single color camera will not display dropped frame messages. If you need these messages you will need to either connect another camera or an eSync into the system.

Computer Memory

Since each color camera can uplink quite a large amount of data over the network, the size of the recorded Take (TAK) can get pretty large. For an example, it a 10-second take was recorded with total data throughput of 1-GBps, the resulting TAK file will be 10-GB, and it can quickly fill up the storage device. Also, especially with multiple color camera systems, it is recommended to use a fast storage drive (e.g. M.2 SSD) that can quickly write recorded capture data from the RAM memory. If the write-out speed to secondary drive isn't fast enough, the occupied memory in RAM storage may gradually increase to its maximum.


Cabling

One or Two Color Cameras

Prime Color cameras connect to the camera system just like other Prime series camera models. Simply plug the camera onto a PoE switch that has enough available bandwidth and it will be powered and synchronized along with other tracking cameras. When you have two color cameras, they will need to be distributed evenly onto different PoE switches so that the data load is balanced out.
PrimeColor TwoCameraSetup.png

Multiple Color Cameras

When using multiple Prime Color cameras, we recommend connecting the color cameras directly into the 10-gigabit uplink switch, because such setup is best for preventing bandwidth bottleneck. A PoE injector will be required if the uplink switch does not provide PoE. This allows the data to travel directly onto the uplink switch and to the host computer through the 10-gigabit network interface. This will also separate the color cameras from the tracking cameras.
PrimeColor MultipleCameraSetup.png

eStrobes

eStrobe Setup

The eStrobe synchronizes with Prime Color cameras through RCA cable connection. It receives exposure signals from the cameras and synchronizes its illuminations correspondingly. Depending on the frame rate of the camera system, the eStrobe will vary its illumination frequency, and it will also vary the percent duty cycle depending on the exposure length. Multiple eStrobes can be daisy-chained in series by relaying the sync signal from the output port to the input port of another as shown in the diagram.


  • PrimeColor eStrobeSetup.png
  • PrimeColor eStrobeSetup2.png

Info2.png

Power Requirement:

The amount of power drawn by each eStrobe will vary depending on the system frame rate as well as the length of camera exposures, because the eStrobe is designed to vary its illumination rate and percent duty cycle depending on those settings.
At maximum, one eStrobe can draw up to 240 Watts of power. A typical 110V wall outlet outputs 110V @ 15A; which totals up to 1650W of power. Also, there may be other factors such as restrictions from the surge protector or extension cords that are used. Therefore, in general, we recommend connecting no more than five eStrobes onto a single power source.

Warning2.png

Warning:

  • Please be aware of the hot surface. The eStrobe will get very hot as it runs.
  • Avoid looking directly at the eStrobe, it could damage your eyes.
  • Make sure the power strips or extension cords are able to handle the power. Using light-duty components could damage the cords or even the device if they cannot sufficiently handle the amount of the power drawn by the eStrobes.
  • The eStrobe is not typically needed for outdoor use. Sunlight should provide enough lighting for the capture.


Capturing without eStrobes

When capturing without eStrobes, the camera entirely relies on the ambient lighting to capture the image. In general, when capturing without an eStrobe, we recommend setting the camera at a lower framerate (30~120 FPS) and increasing the camera exposure to allow for longer exposure time so that the imager can take in more light.

Capturing without eStrobes

When capturing without eStrobes, the camera entirely relies on the ambient lighting to capture the image, and the brightness of the captured frames may vary depending on which type of light source is used. In general, when capturing without an eStrobe, we recommend setting the camera at a lower framerate (30~120 FPS) and increasing the camera exposure to allow for longer exposure time so that the imager can take in more light.

Indoor

Incandescent light flickering. The video was captured at (121 FPS).
When capturing indoors without the eStrobe, you will be relying on the room lighting for brightening up the volume. Here, it is important to note that every type of artificial light source illuminates, or flickers, at a certain frequency (e.g. fluorescent light bulbs typically flicker at 120Hz). This is usually fast enough so that the flickering is not noticeable to human eyes, however, with high-speed cameras, the flickering may become apparent.
When Prime Color captures at a frame rate higher than the ambient illumination frequency, you will start noticing brightness changes between consecutive frames. This happens because, with mismatching frequencies, the cameras are exposing at different points of the illumination phase. For example, if you capture at 240FPS with 120Hz light bulbs lighting up the volume, brightness of captured images may be different in even and odd numbered frames throughout the capture. Please take this into consideration and provide appropriate lighting as needed.

Info2.png

Info: Frequencies of typical light bulbs

  • Fluorescent: Fluorescent light bulbs typically illuminate at 120 Hz with 60 Hz AC input.
  • Incandescent: Incandescent light bulbs typically illuminate at 120 Hz with 60 Hz AC input.
  • LED light bulbs: Variable depending on the manufacturer.
  • eStrobe: LEDs on the eStrobe will be synchronized to the exposure signal from the cameras and illuminate at the same frequency.

Outdoor

When capturing outdoors using Prime Color cameras, sunlight will typically provide enough ambient lighting. Unlike light bulbs, sunlight is emitted continuously, so there is no need to worry about the illumination frequency. Furthermore, the sun is bright enough and you should be able to capture high-quality images by adjusting only the f-stop (aperture size) and the exposure values.

Check Point

Now that you have set up a camera system with Prime Color, all of the connected cameras should be listed under the Devices pane. At this point, you would want to launch Motive and check the following items to make sure your system is operating properly.

  • 2D Frame Delivery: There should be no dropped 2D frames. You can monitor this under the Status Log or from the Devices pane. If frame drops are reported continuously, you can lower down the bit-rate setting or revisit the network configuration and make sure the data loads are balanced out. For more info: #Data Bandwidth.
  • CPU Usage: Open the windows task manager and check the CPU processing load. If only one of the CPU core is fully occupied, the CPU is not fast enough to process data from the color camera. In this case, you will want to use a faster CPU or lower down the bit-rate setting.
  • RAM Usage: Open the windows task manager and check the memory usage. If the RAM usage slowly creeps up to the maximum memory while recording a take, it means the disk driver is not fast enough to write out the color video from RAM. You will have to reduce the bit-rate setting or use a faster disk drive (e.g. M.2 SSD). For more info: #Troubleshooting
  • Hard Drive Space: Take files with color camera data can be quite large sometimes. It is possible to fill your hard drive quickly if recording lightly compress video data from multiple color cameras.

Camera Settings


When you launch Motive, connected Prime Color cameras will be shown in Motive, and you will be able to configure the settings as you would do for other tracking cameras. Open up the Devices pane, and select a Prime Color camera(s), and at the bottom of the pane, key properties that are specific to the selected color cameras will be listed. Optimizing these settings are important in order to capture best quality images without overflowing the network bandwidth. The key settings for the color cameras are image resolution, gamma correction, as well as image compression and data transfer rate settings, which will be covered in the following sections.

Camera Resolution

Default: 1920, 1080

This property sets the resolution of the images that are captured by selected cameras. Since the amount of data increases with higher resolution, depending on which resolution is selected, the maximum allowable frame rate will vary. Below is the maximum allowed frame rates for each respective resolution setting.

Resolution Frame rate
960 x 540 (540p) 500 FPS
1280 x 720 (720p) 360 FPS
1920 x 1080 (1080p) 240 FPS

Compression Mode

Default: Constant Bit Rate.

This property determines how much the captured images will be compressed. The Constant Bit-Rate mode is used by default and recommended because it is easier to control the data transfer rate and efficiently utilize the available network bandwidth.

Constan Bit-Rate

In the Constant Bit-Rate mode, Prime Color cameras vary the degree of image compression to match the data transmission rate given under the Bit Rate settings. At a higher bit-rate setting, the captured image will be compressed less. At a lower bit-rate setting, the captured image will be compressed more to meet the given data transfer rate, but compression artifacts may be introduced if it is set too low.

Variable Bit-Rate

Variable Bit-Rate setting is also available for keeping the amount of the compression constant and allowing the data transfer rate to vary. This mode can be beneficial when capturing images with objects that have detailed textures because it keeps the amount of compression same on all frames. However, this may introduce dropped frames whenever the camera tries to compress highly detailed images because it will increase the data transfer rate; which may overflow the network bandwidth as a result. For this reason, we recommend using the Constant Bit-Rate setting in most applications.

Bit-rate

Default: 50

Available only on Constant Bit-rate Mode

Bit-rate setting determines the transmission rate outputted from the selected color camera. The value given under this setting is measured in percentage (100%) of the maximum data transmission speed, and each color camera can output up to ~100 MBps. In other words, the configured value will indirectly represent the transmission rate in Megabytes per second (MBps). At bit-rate setting of 100, the camera will capture the best quality image, however, it could overload the network if there is not enough bandwidth to handle the transmitted data.

Since the bit-rate controls the amount of data outputted from each color camera, this is one of the most important settings when properly configuring the system. If your system is experiencing 2D frame drops, it means one of the system requirements is not met; either network bandwidth, CPU processing, or RAM/disk memory. In such cases, you could decrease the bit-rate setting and reduce the amount of data output from the color cameras.

Image Quality

The image quality will increase at a higher bit-rate setting because it records a larger amount of data, but this will result in large file sizes and possible frame drops due to data bandwidth bottleneck. Often, the desired result is different depending on the capture application and what it is used for. Thus, the below graph illustrates how data size how they are related.

ColorCamear NoStrobe.png


Info2.png

Tip: Monitoring data output from each camera

Data output from the entire camera system can be monitored through the Status Panel. Output from individual cameras can be monitored from the 2D Camera Preview pane when the Camera Info is enabled under the visual aids (Viewport16.png) option.

PrimeColor DataOutput.png

Gamma

Default : 24

Gamma correction is a non-linear amplification of the output image. The gamma setting will adjust the brightness of dark pixels, midtone pixels, and bright pixels differently, affecting both brightness and contrast of the image. Depending on the capture environment, especially with a dark background, you may need to adjust the gamma setting to get best quality images.

  • PrimeColor Gamma1.png
  • PrimeColor Gamma2.png

Data Recording / Export


Once you have set up the system and configured the cameras correctly, Motive is now ready to capture Takes. Recorded TAK files will contain color video along with the tracking data, and you can play them back in Motive. Also, the color reference video can be exported out from the TAK.

Data Recording

Once the camera is set up, you can start recording from Motive. Captured frames will be stored within the TAK file and you can access them again in Edit mode. Please note that capture files with Prime Color video images will be much larger in file size.

Data Export

Once the color videos have been saved onto TAK files, the captured reference videos can be exported into AVI files using either H.264 or MJPEG compression format. The H.264 format will allow faster export of the recorded videos and is recommended. Video for the current TAK can be exported by clicking File tab -> Export Video option in Motive, or you can also export directly from the Data pane by right-clicking on the Take(s) and clicking Export Video from the context menu. The following export dialogue window will open and you will be able to configure the export settings before outputting the files:

PrimeColor DataExport.png


Troubleshooting


› Q : Slow memory write out

A: If the disk drive on the host PC is not fast enough to write the data, the RAM usage will gradually creep up to its maximum memory when recording a capture. In which case, the recorded TAK file may be corrupted or incomplete. If you are seeing this issue, you will have to lower down the bit-rate to reduce the amount of data or use a faster disk drive.

PrimeColor RAMCreep.png

› Q : There are frame drops even when there is enough bandwidth availability

A: Dropped 2D frames with Prime Color in the system can be introduced due to the following issue:

  • Network Bandwidth: Insufficient network bandwidth will cause frame drops. You will have to make sure the network setup, including the network switches, Ethernet cables, and the network adapter on the host PC, is capable of transmitting and receiving data fast enough. See: #Data Bandwidth
  • Audio playing in background (MMCSS): When playing audio using applications (e.g. Chrome, VLC) that registers to Multimedia Class Scheduler Service (MMCSS), it will interfere with how the CPU resource is used in Motive. This service will prioritize time-sensitive multimedia applications to utilize the CPU resources as much as possible, which may cause increased latency which may lead to dropped frames. We recommend exiting out from such applications if there are any latency and frame drop issues.