Video feeds#

Video feeds from different cameras:

  • frontal

  • vertical

  • stereo pair (left, right)

  • disparity map

  • depth map

  • depth from motion

  • occupancy grid

Frontal#

Frontal video feed parameters depend on recording and streaming configuration. The parameters for the default recording mode (4K UHD) are defined below.

Parameters

Physical/Simulated drone

Width (px)

3840/1280

Height (px)

2160/720

Format

NV21

FPS

30

Name

fcam_recording

Frontal video feed parameters for streaming.

Parameters

Physical/Simulated drone

Width (px)

1920/1280

Height (px)

1080/720

Format

NV21

FPS

30

Name

fcam_streaming

Vertical#

Video feed parameters from vertical camera.

Parameters

Physical/Simulated drone

Width (px)

320

Height (px)

240

Format

grey (8 bits)

FPS

60

Hfov (°)

53.71

Vfov (°)

40

Name

vcam_raw
../_images/vcam_03750_qvga.png

Stereo pipeline#

The stereo camera allows to compute 3D environment information. (see here for more details). The next schema represents the different feeds available.

../_images/20-Pipeline-Video.jpg

Stereo pair reference image#

Rectified video feed from the stereo right camera. The rectified image is computed using a pinhole camera model and stereo calibration.

Parameters

Physical/Simulated drone

Width (px)

1408/1280

Height (px)

720

Format

grey (8 bits)

FPS

30

Hfov (°)

110

Vfov (°)

72

Name

fstcam_right_rectified

Disparity map#

Each pixel of the disparity map represents the distance between the corresponding point in stereo left and right camera. The disparity is given in the rectified right image reference. This is computed by comparing visual difference between left and right picture. If the disparity cannot be computed, the values are set to:

  • 255 Not available.

  • 254 DroneMask in Left Stereo-Image.

  • 253 DroneMask in Right Stereo-Image.

  • 252 DroneMask in both Stereo Images.

  • 251 Sky (infinite).

Parameters

Physical/Simulated drone

Width (px)

176

Height (px)

90

Format

uint8

FPS

30

Hfov (°)

110

Vfov (°)

72

Range

[0 - 96]

Name

fstcam_stereo_disparity_filtered

Note

The range of disparity values is [0 - 96] with a quantification step of 0.5. These values are integers, so they are stored in a range from [0 - 192].

Depth map#

Image containing depth information. The depth is computed from the disparity image. The depth is given in the rectified right image reference. If the depth cannot be computed, the values are set as NA (not available).

The depth information is the distance between the observed point and the image plane.

Parameters

Physical/Simulated drone

Width (px)

176

Height (px)

90

Format

raw32 (interpreted as float32)

FPS

30

Hfov (°)

110

Vfov (°)

72

Range

[30cm - 11m]

Name

fstcam_stereo_depth_filtered

Occupancy grid#

3D map of the environment as an evenly spaced voxel. Each containing the probability of presence of an obstacle.

Probabilities are stored as logodd :

  • logodd(p) = log( p /(1-p) )

  • Value between [-100- 100].

  • Value stored as int8.

  • Positive values mean that there is an obstacle in the voxel.

  • Negative values mean that the voxel is empty.

  • 0 value means that the information is unknown.

The occupancy grid size is 64x64x32, the dimension voxel is 0.4mx0.4mx0.4m.

The occupancy grid translates in NED along with the drone, so that the drone position is always in the middle of the grid (32x32x16).

The occupancy grid orientation never changes with respect to NED frame.

../_images/og_logan.gif