Hello,
I am using RTABMap SLAM with RGBD images and would like to further process the RGB and depth images associated with RTABMap key frames in real time.
Here is the command I used to launch RTABMap:
```
ros2 launch rtabmap_launch rtabmap.launch.py
rtabmap_args:="--delete_db_on_start"
rgb_topic:=/zed/rgb/image_rect_color
depth_topic:=/zed/depth/depth_registered
camera_info_topic:=/zed/depth/camera_info
frame_id:=zed_camera_link
imu_topic:=/zed/imu/data
```
To find the RGB and depth images associated with RTABMap key frames in real time, I am using the `get_map_data` service to get the
rtabmap_msgs/MapData message and the
rtabmap_msgs/SensorData message within it. The raw images `left` and `right` are both empty. The compressed RGB image `left_compressed` looks fine, and I am able to successfully uncompress it in Python using OpenCV. But the `right_compressed` image seems to be in an RGBA format. It is the same resolution as my depth image, but with four channels ranging from 0-255, instead of one channel ranging from 0-10000. I am having trouble uncompressing this into a useful format.
If I create my map first and export my database using this command:
`rtabmap-export --images_id --poses_camera --poses_format 11 <path-to-database>.db`
Then the depth images look great. Here is the format:
rtabmap_export depth Image Header:
Format: PNG
Mode: I;16
Size: (640, 360)
But when I use the get_map_data service as described, or even the get_node_data service, this is the format:
ros get_node_data, get_map_data service right_compressed Image header:
Format: PNG
Mode: RGBA
Size: (640, 360)
How would you recommend uncompressing the depth images from the map?