I can't understand pointcloud2 data [closed]
Ubuntu 18.04 Ros Melodic
rostopic echo /os_cloud_node/points
header:
seq: 57363
stamp:
secs: 6366
nsecs: 847305660
frame_id: "os_sensor"
height: 16
width: 1024
fields:
-
name: "x"
offset: 0
datatype: 7
count: 1
-
name: "y"
offset: 4
datatype: 7
count: 1
-
name: "z"
offset: 8
datatype: 7
count: 1
-
name: "intensity"
offset: 16
datatype: 7
count: 1
-
name: "t"
offset: 20
datatype: 6
count: 1
-
name: "reflectivity"
offset: 24
datatype: 4
count: 1
-
name: "ring"
offset: 26
datatype: 2
count: 1
-
name: "ambient"
offset: 28
datatype: 4
count: 1
-
name: "range"
offset: 32
datatype: 6
count: 1
is_bigendian: False
point_step: 48
row_step: 49152
data: [198, 131, 166, 191, 109, 184, 151, 189, 79, 129, 194, 62, 0, 0, 128, 63, 0, 0, 185, 67, 0, 0, 0, 0, 104, 0, 0, 0, 38, 1, 0, 0, 68, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 101, 251, 131, 191, 96, 237, 85, 189, 78, 158, 157, 62, 0, 0, 128, 63, 0, 0, 57, 67, 222, 127, 1, 0, 53, 0, 0, 0, 17, 1, 0, 0, 44, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 128, 0, 0, 0, 128, 0, 0, 0, 0, 0, 0, 128, 63, 0, 0, 0, 0, 72, 0, 3, 0, 0, 0, 0, 0, 219,
def func(veri):
ldrdata=veri.data
print(type(ldrdata)) #string
print(ldrdata)
the output:
If there is an obstacle 3 meters ahead, I want to get this number 3. How should I use pointcloud2 data for this?
Thanks in advance
The
data[]is a serialized form of the original data, and you are not expected to read the values directly. There are pre-existing methods to convert it back into useful format. For example, see the "walle" answer to #q202787.I've closed this as a duplicate, as there are a number of previously asked (and answered) Q&As which seem to discuss the same topic: see #q273182, #q373094, #q300906, #q349814, #q319350 and #q294913 for instance. And #q399882, which was asked only three weeks ago.
There are many more. A google search with
site:answers.ros.orgshould return them.