Image Sampler

Image Sampler Node

The image sampler subscribes to an image topic, then republishes the images at a different rate and resolution.

Two steps are required to start using the image sampler:

Configure the image sampler for the desired camera

rosservice call /mgt/img_sampler/{nav_cam,dock_cam}/configure \
                  <mode> <framerate> <width> <height> <bitrate>

• mode : parameters apply to RECORDING=1, or STREAMING=2 or BOTH=3
• framerate : rate in Hz to publis
• with, height : dimension in pixels of the image to publish
• bitrate : only applies to SciCam, defines the image quality

Example to configure the nav_cam to publish half size images every 2 seconds (both for streaming and recording):

rosservice call /mgt/img_sampler/nav_cam/configure 0 0.5 640 480 0

See Configure Camera Service.

Enable the image sampler for the desired camera

rosservice call /mgt/img_sampler/{nav_cam.dock_cam}/enable <mode> <flag>

• mode : parameters apply to RECORDING=1, or STREAMING=2 or BOTH=3
• flag : true to enable and false to disable the service

Example to turn on streaming only of the nav_cam (using previous camera configuration):

rosservice call /mgt/img_sampler/nav_cam/enable 2 true

See EnableCamera Service.

Then, the node will publish an image at the desired resolution and rate, with the topic name <node name>/image.

The image to read is specified through the command line argument --input_topic.