What does 'nan' mean in lidar's scan data?
Hello, I'm working with the ROS kinetic of Ubuntu 16.04.
I'm also using Hokuyo's lidar sensor and recently realized that there are some strange data in the returned data of /scan topic.
The nan data, which stands for 'not a number', is that; if so, what is the 'nan'?
Although I've worked with a lidar sensor for over 2 years, I have no idea about when the nan data is created.
What's the nan in this? It doesn't matter when it comes to the g-mapping or other packages, but I need to do another work whit this data and nan makes no sense.
If someone familiar with lidar's range data is here, would you please give me some help?
The below is the /scan data including nan.
header:
seq: 6147
stamp:
secs: 1627028918
nsecs: 664962817
frame_id: "base_footprint"
angle_min: -2.07394194603
angle_max: 2.07394218445
angle_increment: 0.00613592332229
time_increment: 2.71259814326e-05
scan_time: 0.0277769993991
range_min: 0.019999999553
range_max: 5.59999990463
ranges: [nan, nan, 2.802000045776367, 2.7309999465942383, 2.7090001106262207, 2.677000045776367,...]
Thanks :)
(add)
According to this page, I think the nan data might mean the max_range value. Is it right?
It's corect! There is no obstacle at the maximum reading range. BTW, you've tested this lidar only indoor?
@Ktysai Thanks for the kind comment. Yeah, I've never used it on the road..
Your linked questions (or the best answer to that) speaks from two modes ( urg_node or the hokuyo_node). Which mode are you using? Which error code do you get?