the map vanish when it is not visible

[rushelby123]

hello, the problem is that the map is updated every second but the result I would like to get is that the map remains even if it is no longer visible. how can i fix this?

[rushelby123]

This are the parameters that are written in config/elevation_mapping/simple_demo.yaml
(note that if i use the command rostopic list |grep points nothing appears, may this be a problem if yes how can i solve this problem?)

point_cloud_topic: "/points"
map_frame_id: "odom"
robot_base_frame_id: "base_footprint"
#robot_pose_with_covariance_topic: "/base_footprint_pose"
robot_pose_cache_size: 500
track_point_frame_id: "base_footprint"
track_point_x: 0.0
track_point_y: 0.0
track_point_z: 0.0
min_update_rate: 2.0
time_tolerance: 0.5
sensor_processor/ignore_points_above: 0.5
robot_motion_map_update/covariance_scale_translation_x: 0.0
robot_motion_map_update/covariance_scale_translation_y: 0.0
robot_motion_map_update/covariance_scale_translation_z: 0.0
robot_motion_map_update/covariance_scale_rotation_x: 0.0
robot_motion_map_update/covariance_scale_rotation_y: 0.0
robot_motion_map_update/covariance_scale_rotation_z: 0.0

length_in_x: 4.0
length_in_y: 4.0
position_x: 0.0
position_y: 0.0
resolution: 0.1
min_variance: 0.0001
max_variance: 0.05
mahalanobis_distance_threshold: 2.5
multi_height_noise: 0.01
fused_map_publishing_rate: 2.0
enable_skip_lower_points: true
scanning_duration: 0.01
remove_penetrated_points_rate: 5.0