[ERROR] (2026-04-18 12:06:04.784) Rtabmap.cpp:1408::process() RGB-D SLAM mode is enabled, memory is incremental but no odometry is provided. Image 0 is ignored!

[Parastou Bakhtiari]

Hi Matlabbe,

I have an issue while using the rtabmap.ros in rgb-d mode and using visual_odometry=true

with this command:
ros2 launch rtabmap_launch rtabmap.launch.py   args:="--delete_db_on_start"   frame_id:=zed_left_camera_optical_frame   visual_odometry:=true   rgb_topic:=/left/image_rect   depth_topic:=/stereo/depth_sgbm   camera_info_topic:=/left/camera_info_fixed   rviz:=true   approx_sync:=true   rgbd_sync:=true   approx_rgbd_sync:=true   topic_queue_size:=30   wait_imu_to_init:=false   use_sim_time:=true

I am trying to not use the /odometry_true topic in my bag and just rely on visual odometry.
I am wondering if the issue is my depth topic and I will not get this error if I have better depth images with less NaN values.

Would you please confirm this? or the rtabmap still needs the correct odometry topic even in that case?

you may find the recorded bag here: https://drive.google.com/drive/folders/15fMnaFpHj2YdzMMj__Vn3BsuJa1bxfLN?usp=sharing

[matlabbe]

Hi,

There are some warnings about incompatible QoS:

[rgbd_sync-1] [WARN] [1776543913.680043649] [rtabmap.rgbd_sync]: New publisher discovered on topic '/left/camera_info_fixed', offering incompatible QoS. No messages will be sent to it. Last incompatible policy: RELIABILITY_QOS_POLICY
[point_cloud_xyzrgb-6] [WARN] [1776543913.716303805] [point_cloud_xyzrgb]: New publisher discovered on topic '/left/camera_info_fixed', offering incompatible QoS. No messages will be sent to it. Last incompatible policy: RELIABILITY_QOS_POLICY

We can fixed it by adding "qos_camera_info:=2" to your command:

ros2 launch rtabmap_launch rtabmap.launch.py   \
   args:="--delete_db_on_start"   \
   frame_id:=base_link   \
   visual_odometry:=true   \
   rgb_topic:=/left/image_rect   \
   depth_topic:=/stereo/depth_sgbm   \
   camera_info_topic:=/left/camera_info_fixed   \
   rviz:=true   \
   approx_sync:=false   \
   rgbd_sync:=true   \
   approx_rgbd_sync:=false   \
   topic_queue_size:=30   \
   wait_imu_to_init:=false   \
   use_sim_time:=true  \
   qos_camera_info:=2

Note that I also set approx_sync and approx_rgbd_sync to false and added an optical rotation to the camera, thus changed frame_id to base_link above. We have to launch this static transform:

ros2 run tf2_ros static_transform_publisher --roll -1.570796327 --yaw -1.570796327 --frame-id base_link --child-frame-id zed_left_camera_optical_frame

then play the bag:

ros2 bag play rosbag2_2026_04_16-11_31_40_0.db3 --clock