ZED Stereo Camera ROS Node¶

ZED stereo camera ROS node based on OpenCV VideoCapture API for publishing left and right raw images and their camera_info.

Usage¶

Obtain the stereo camera calibration data file for your ZED camera (with a particular serial number) with one of two ways described below. (TI-Internal: calibration data files are available under <zed_capture>/config for SN5867575 and SN29788442).

Find the calibration file in cd /usr/local/zed/settings, or download it from http://calib.stereolabs.com/?SN=xxxx, where xxxx is the serial number (SN) of your ZED camera.

Place the calibration data file (SNxxxx.conf) under <zed_capture>/config.
Generate camera_info YAML files, and undistortion & rectification look-up-table (LUT) files which are required in offloading the undistortion/rectification computation on J7 VPAC/LDC hardware accelerator.

Run the following script:
```
python2 <zed_capture>/script/generate_rect_map.py -i SNxxxx.conf -m <camera_mode>
```
where
- <zed_capture> is the folder where the ZED camera node is installed (try rospack find zed_capture after catkin_make),
- SNxxxx.conf is the factory calibration data file obtained from Step 1, and
- <camera_mode> is camera mode. Valid <camera_mode>: 2K, FHD, HD, HD2, VGA (see Launch File Parameters section for description). If the -m argument is not provided, by default the tool will iterate for the following three camera modes: HD, HD2, and FHD.
This script parses the calibration data and generates the following files:
- <zed_capture>/config/<SN_string>_<camera_mode>_camera_info_{left,right}.yaml: camera_info for left and right raw image
- <zed_capture>/config/<SN_string>_<camera_mode>_remap_LUT_{left,right}.bin: undistortion and rectification remap LUT for left and right raw images.
Update <zed_capture>/launch/zed_capture.launch to modify zed_sn_str parameter. Also update relevant parameters in nodes/*/params.yaml files for each of demo applications.

Build the ZED camera ROS node

cd $CATKIN_WS
catkin_make
source devel/setup.bash

Launch the ZED camera node

roslaunch zed_capture zed_capture.launch

Launch File Parameters¶

Parameter	Description	Value
zed_sn_str	ZED camera SN string	string
device_name	camera device name. Typically `/dev/video0` on the target	string
camera_mode	ZED camera mode	'2K' (2208x1242)
_	_	'FHD' (1920x1080)
_	_	'HD' (1280x720)
_	_	'HD2' (1280x720)*
_	_	'VGA' (672x376)
frame_rate	frame rate at which raw images are published	int
encoding	image encoding	'yuv422' (default) or 'bgr8'

‘HD2’ is a newly added mode that provides 720p resolution for experiments that need a longer focal length than the native ‘HD’. The images are obtained by center-cropping the original 1080p images captured from the ‘FHD’ mode.

When encoding is set to ‘yuv422’, the pixel format YUV422::YUYV from the ZED camera is converted to YUV422::UYVY format considering the compatibility with LDC hardware accelerator.

Data Collection Steps¶

Connect the ZED camera to UBS 3 port (a USB type-A to type-C adaptor is required on J7 EVM). Check if the camera is recognized with ls /dev/video*. In a Ubuntu PC with a built-in webcam, the stereo camera can be recognized as /dev/video2; while in J7 host Linux it may be recognized as /dev/video0.
If necessary, update launch/zed_capture.launch to change video device, camera mode, frame rate, and etc.
On the first terminal, launch the ZED capture node with following, and keep it running:
```
$ roslaunch zed_capture zed_capture.launch
```

On the second terminal, to capture into ROS bag files, run one of two examples below

# Collect 15 seconds of data and stop itself
$ roslaunch zed_capture recordbag.launch
# Save into a series of bag files, each keeping 15 seconds of data, until terminated with Ctrl+C
$ roslaunch zed_capture recordbag_split.launch

(Optional to check the ROS topics) On 3rd terminal,

$ rostopic list
$ rqt_image_view /camera/left/image_raw

By default, ROS bag files are stored under ${HOME}/.ros folder.

Note: It is not recommended combining the zed_capture node and ROSBAG capture into a single launch file, since it takes some several seconds for the ZED camera to settle down its ISP tuning after the ZED camera node is started.