Pose message lost decimal
Good morning!
I am dealing with gps data that I convert and published into a geometry_msgs::PoseWithCovarianceStamped.
Thus I am supposed to publish "large" values (x~330 000, y~420 000), but I could see that I loose completely the decimals values on the code.
When I do "rostopic echo" I have this:
header:
seq: 29
stamp:
secs: 1590407673
nsecs: 738122463
frame_id: "/map"
pose:
pose:
position:
x: 330288.65625
y: 4156626.75
z: 43.8396682739
orientation:
x: -0.0146753482234
y: 0.000946441286636
z: 0.990484373245
w: 0.136837293016
covariance: [0.6361376939995259, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.6361376939995259, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.6361376939995259, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.6361376939995259]
But by displaying via the code (std::cout) I got this:
pose 330287 4.15663e+06
NB:Using also the initial pose tool on RVIZ gives me the same behavior.
Is there a reason, I must miss, that explains why I find this behavior? If yes is there any way to get the decimals (avoiding to shift everything to get closer to 0) ?
PS: Therefore I found that using a printf with the %lf gives me the decimals... And using static_cast<double> does not solve the problem.
This is likely not a problem with lost decimals, but with how you've configured
std::cout.By default it prints only a limited number of significant digits.
But that doesn't mean they are lost. They just aren't displayed.
note though: double precision floating point numbers do support only approx 15 significant digits, so with the large numbers you mention, you're already using about half of that.
See also #q286682.
Finally: as everything in ROS is in metres, the values you quote would be 330 Km and 420 Km respectively. As a
PoseStampedis relative to some origin, REP-105 mentions some considerations when dealing with very large distances. See the Transitions between maps section.See #q248060 for what I believe is almost a duplicate of your question.
Ok I see... I might have been confused about that only half of numbers have been displayed and what's left after the comma not considered, whereas it is that part I was considering for my application. I will post an answer in order to close this request.