NAO - Video camera


Two identical video cameras are located in the forehead.

They provide a up to 1280x960 resolution at 30 frames per second. They can be used to identify objects in the visual field such as goals and balls, and bottom camera can ease NAO’s dribbles.

2D Camera

Camera indexes

The camera indexes are:

Parameter ID Name ID Value Description
AL::kTopCamera 0 camera on the top.
AL::kBottomCamera 1 camera on the bottom.

Location

/sites/default/files/repository/69_html_nao/_images/hardware_camera_lateral_4.0.png
/sites/default/files/repository/69_html_nao/_images/hardware_camera_top_4.0.png
Camera name X(m) Y(m) Z(m) WX(rd)[deg]* WY(rd)[deg]* WZ(rd)[deg]*
CameraTop 0.05871 0.0 0.06364 0.0 0.0209 [1.2] 0.0
CameraBottom 0.05071 0.0 0.01774 0.0 0.6929 [39.7] 0.0

Note

We adopt the roll, pitch and yaw notation for angle representation. So, to construct an homogeneous transform with rotation (Wx,Wy,Wz) use T=rotZ(Wz)*rotY(Wy)*rotX(Wx).

Specifications

Camera Model MT9M114
Type SOC Image Sensor
Imaging Array Resolution 1.22 Mp
Optical format 1/6 inch
Active Pixels (HxV) 1288x968
Sensitivity Pixel size 1.9µm*1.9µm
Dynamic range 70 dB
Signal/Noise ratio (max) 37dB
Responsivity 2.24V/Lux-sec (550 nm)
Output Camera output 1280*960@30fps
Data Format (YUV422 color space)
Shutter type Electronic Rolling shutter (ERS)
View Field of view 72.6°DFOV (60.9°HFOV,47.6°VFOV)
Focus range 30cm ~ infinity
Focus type Fixed focus

Parameters

The camera has a list of parameters which can be modified.

Model

Camera Model has the following value:

Parameter ID Name ID Value Description
AL::kMT9M114 2 HD Camera

Supported parameters

Software parameters
Parameter Min value Max value Default value Camera ID name ID value
Keep Alive 0 1 0 kCameraKeepAliveID 35
Hardware parameters
Parameter Min Value Max Value Default Value Camera ID name ID value Remarks
Brightness 0 255 55 kCameraBrightnessID 0 Auto Exposition must be enabled
Contrast 16 64 32 kCameraContrastID 1 The contrast value represents the gradient of the contrast adjustment curve, measured at the target brightness point (as controlled by Brightness parameter). The device supports a range of gradients from 0.5 to 2.0; Device represents this as a contrast range from 16 (0.5) to 64 (2.0).
Saturation 0 255 128 kCameraSaturationID 2  
Hue -180 180 0 kCameraHueID 3 Disabled
Gain 32 255 32 kCameraGainID 6 Auto Exposition must be disabled
Horizontal Flip 0 1 0 kCameraHFlipID 7  
Vertical Flip 0 1 0 kCameraVFlipID 8  
Auto Exposition 0 1 1 kCameraAutoExpositionID 11  
Auto White Balance 0 1 1 kCameraAutoWhiteBalanceID 12  
Camera Resolution kQVGA k4VGA kQVGA kCameraResolutionID 14 Not to be set manually
Frames Per Second 1 30 5 kCameraFrameRateID 15 Not to be set manually
Exposure (time in ms = value / 10) 1 2500 (250ms) NA kCameraExposureID 17 Auto Exposition must be disabled otherwise display last value before auto exposure was activated. Once auto exposure disabled paremeter is set to the last value used by the camera internal algorithm
Camera Select 0 1 0 kCameraSelectID 18 0: Bottom Camera 1: Top Camera
Reset camera registers 0 1 0 kCameraSetDefaultParamsID 19 1: reset camera and reset parameter to 0
Auto Exposure Algorithm 0 3 1 kCameraExposureAlgorithmID 22
  • 0: Average scene Brightness
  • 1: Weighted average scene Brightness
  • 2: Adaptive weighted auto exposure for hightlights
  • 3: Adaptive weighted auto exposure for lowlights

For further details, see: Auto Exposure Algorithm.

Sharpness -1 7 0 kCameraSharpnessID 24 -1: disabled
White Balance (Kelvin) 2700 6500 NA kCameraWhiteBalanceID 33 Read only if Auto White Balance is enabled Read/Write if Auto White Balance is disabled
Back light compensation 0 4 1 kCameraBacklightCompensationID 34  
Auto Exposure Algorithm

For auto exposure algorithm, the measurement engine subdivides the image into 25 windows organized as a 5 x 5 grid with the following weight:

M_{weight} = \begin{tabular}{|c|c|c|c|c|}
\hline
0.25 & 0.25 & 0.25 & 0.25 & 0.25 \\ \hline
0.25 & 0.75 & 0.75 & 0.75 & 0.25 \\ \hline
0.25 & 0.75 & 1.00 & 0.75 & 0.25 \\ \hline
0.25 & 0.75 & 0.75 & 0.75 & 0.25 \\ \hline
0.25 & 0.25 & 0.25 & 0.25 & 0.25 \\
\hline
\end{tabular}

Example illustrating the impact of Auto Exposure Algorithm parameter:

/sites/default/files/repository/69_html_nao/_images/AutoExposureAlgorithm_averagelight.png /sites/default/files/repository/69_html_nao/_images/AutoExposureAlgorithm_highlight.png /sites/default/files/repository/69_html_nao/_images/AutoExposureAlgorithm_lowlight.png
0: Average scene Brightness 2: Adaptive weighted auto exposure for highlights 3: Adaptive weighted auto exposure for lowlights

Supported colorspaces

A color space is a model describing the way to represent color as an ordered list of numbers. For example you can represent the color of each pixel of your screen as a list of three elements R, G and B. Which are respectively the value of Red, Green, and Blue usually stored in an byte (range from 0 to 255).

Setting the color space allows you to set the image buffer encoding in AL::ALImage.

Color space parameter for 2D camera can have the following values:

Parameter ID Name ID Value Number of layers Number of channels Description
AL::kYuvColorSpace 0 1 1 Buffer only contains the Y (luma component) equivalent to one unsigned char
AL::kyUvColorSpace 1 1 1 Buffer only contains the U (Chrominance component) equivalent to one unsigned char
AL::kyuVColorSpace 2 1 1 Buffer only contains the V (Chrominance component) equivalent to one unsigned char
AL::kRgbColorSpace 3 1 1 Buffer only contains the R (Red component) equivalent to one unsigned char
AL::krGbColorSpace 4 1 1 Buffer only contains the G (Green component) equivalent to one unsigned char
AL::krgBColorSpace 5 1 1 Buffer only contains the B (Blue component) equivalent to one unsigned char
AL::kHsyColorSpace 6 1 1 Buffer only contains the H (Hue component) equivalent to one unsigned char
AL::khSyColorSpace 7 1 1 Buffer only contains the S (Saturation component) equivalent to one unsigned char
AL::khsYColorSpace 8 1 1 Buffer only contains the Y (Brightness component) equivalent to one unsigned char
AL::kYUV422ColorSpace 9 2 2 Native format, 0xY’Y’VVYYUU equivalent to four unsigned char for two pixels. With Y luma for pixel n, Y’ luma for pixel n+1, and U and V are the average chrominance value of both pixels.
AL::kYUVColorSpace 10 3 3 Buffer contains triplet on the format 0xVVUUYY, equivalent to three unsigned char
AL::kRGBColorSpace 11 3 3 Buffer contains triplet on the format 0xBBGGRR, equivalent to three unsigned char
AL::kHSYColorSpace 12 3 3 Buffer contains triplet on the format 0xYYSSHH, equivalent to three unsigned char
AL::kBGRColorSpace 13 3 3 Buffer contains triplet on the format 0xRRGGBB, equivalent to three unsigned char
AL::kYYCbCrColorSpace 14 2 2 TIFF format, four unsigned characters for two pixels.
AL::kH2RGBColorSpace 15 3 3 H from “HSY to RGB” in fake colors.
AL::kHSMixedColorSpace 16 3 3 HS and (H+S)/2.

Supported resolutions

Resolution parameter can have the following values:

Parameter ID Name ID Value Description
AL::kQQQQVGA 8 Image of 40*30px
AL::kQQQVGA 7 Image of 80*60px
AL::kQQVGA 0 Image of 160*120px
AL::kQVGA 1 Image of 320*240px
AL::kVGA 2 Image of 640*480px
AL::k4VGA 3 Image of 1280*960px

Note

The camera MT9M114 can only run internally from QVGA to 4VGA, otherwise scale down is performed (without binning).

Supported framerates

Here a list of supported frame rates according to resolution set.

Resolution Supported Framerate
AL::kQQQQVGA from 1 to 30 fps
AL::kQQQVGA from 1 to 30 fps
AL::kQQVGA from 1 to 30 fps
AL::kQVGA from 1 to 30 fps
AL::kVGA from 1 to 30 fps
AL::k4VGA from 1 to 30 fps

Note

The camera MT9M114 can only run internally from 5 to 30 fps.