Too Many Unknowns in Map

[InDroKalena]

Hello!

I am using RTAB to map an environment in Isaac Sim using a stereo ZED X camera and ROS2. I am getting what I think is a good number of inliers with stereo odom, as shown below, yet my stereo map is largely made up of unknowns. I have included my rtabmap launch file below - please let me know if you have any advice! My colleague suggested that it could be that the environment is too plain, especially with the white floor and walls, but I changed these colours and am still seeing a similar result. Let me know if I can provide any other information to make this issue more clear. Thank you in advance!

from launch import LaunchDescription
from launch_ros.actions import Node
from launch.substitutions import LaunchConfiguration
from launch.actions import DeclareLaunchArgument

def generate_launch_description():
use_sim_time = LaunchConfiguration('use_sim_time')
rtabmap_args = LaunchConfiguration('rtabmap_args')
database_path = LaunchConfiguration('database_path')
localization = LaunchConfiguration('localization')

return LaunchDescription([
    DeclareLaunchArgument('use_sim_time', default_value='true'),
    DeclareLaunchArgument('rtabmap_args', default_value='--delete_db_on_start'),
    DeclareLaunchArgument('database_path', default_value='/my/path/to/rtabmap.db'),
    DeclareLaunchArgument('localization', default_value='false'),

    Node(
        package='rtabmap_slam',
        executable='rtabmap',
        name='rtabmap',
        output='screen',
        parameters=[{
            'use_sim_time': use_sim_time,
            'frame_id': 'base_footprint',
            'subscribe_depth': False,
            'subscribe_rgb': False,
            'subscribe_stereo': True,
            'visual_odometry': True,
            'approx_sync': False,
            'odom_frame_id': 'odom',
            'stereo_approx_sync': False,
            'stereo_namespace': '/zed/zed_node',
            'imu_topic': '/zed/zed_node/imu/data',
            'queue_size': 10,
            'qos': 1,
            'rtabmap_args': rtabmap_args,
            'database_path': database_path,
            'localization': localization,
            'map_frame_id': 'map',
            'wait_for_transform': 5.0,
            'RGBD/CreateOccupancyGrid': 'true',
            'Grid/Sensor': 'true',
            'rtabmapviz' : 'true',
            'map_always_update': True,
            'map_empty_ray_tracing': True,
        }],

        remappings=[
                ('left/image_rect', '/zed/zed_node/left/image_rect_color'),
                ('left/camera_info', '/zed/zed_node/left/camera_info'),
                ('right/image_rect', '/zed/zed_node/right/image_rect_color'),
                ('right/camera_info', '/zed/zed_node/right/camera_info'),
            ]
    ),


    Node(
        package='rtabmap_odom', executable='stereo_odometry', name='stereo_odometry', output='screen',
        parameters=[{
            "frame_id": 'base_footprint',
            "odom_frame_id": 'odom',
            "publish_tf": True,
            "wait_for_transform": 5.0,
            "wait_imu_to_init": False,
            "sync_queue_size": True,
            "qos": 1,
            "subscribe_rgbd": False,
            'rtabmapviz' : 'true',
        }],

        remappings=[
                ('left/image_rect', '/zed/zed_node/left/image_rect_color'),
                ('left/camera_info', '/zed/zed_node/left/camera_info'),
                ('right/image_rect', '/zed/zed_node/right/image_rect_color'),
                ('right/camera_info', '/zed/zed_node/right/camera_info'),
                ('imu', '/zed/zed_node/imu/data'),
            ]
        ),    
])

[matlabbe]

Something looks off in the image you shared, the stereo images don't look correctly stereo rectified as we can see vertical disparity. That would affect the quality of the point cloud a lot, and also would cause very bad odometry.

Beside that, the floor is indeed textureless, so no depth would be computed on it. If you can see only obstacles and want more empty cells in the map, you can enable ray tracing:

'Grid/3D': 'false',
'Grid/RayTracing': 'true',
'Grid/NormalsSegmentation': 'false',
'Grid/MaxGroundHeight': '0.1',

[InDroKalena]

Thank you so much! I will keep playing around with parameters but these simple changes helped immediately.