Summary

This package provides a simple way of processing and extracting camera images from a stored bag file. Many bags will store only the raw_image and camera_info, either because the creators want to avoid the overhead of running image_proc or to minimize the amount of redundant information stored in the bag. bag_to_images runs on a bag file, performs the same processing as an image_proc node, and saves the resulting images to disk as separate files. One of the main advantages of bag_to_images is that unlike setting up a full ROS graph to do the same processing there is no worry of dropped images.

Usage

Basic usage (dumps colorized rectified images from left wide stereo camera):

bag_to_images --bag [filename].bag

To see the various options available:

bag_to_images

Dumping .png files:

bag_to_images --bag [filename].bag --extension png

To dump (rectified) images from the right narrow camera:

bag_to_images --bag [filename].bag --camera /narrow_stereo/right --color false

Implementation Notes

This package depends on the rosrecord C++ API, which is likely to change at some point. It also depends on the unreleased C++ API for image_proc, which is relatively stable.

Handling of camera_info

The camera model used for rectification is updated whenever a new camera_info message is encountered in the bag file. Until at least one such message has been encountered images will be dropped.

Possible future extensions

• A progress indicator would be useful and can be added when the rosrecord API provides some feedback about progress.
• Stereo processing might be useful, and options could be added to process and produce point cloud files and/or disparity maps