Official RTAB-Map Forum - Re: Build a map with the image transformed wirelessly

Re: Build a map with the image transformed wirelessly

Posted by matlabbe on
URL: http://official-rtab-map-forum.206.s1.nabble.com/Build-a-map-with-the-image-transformed-wirelessly-tp364p366.html

Hello,

I assume that you are running rtabmap on the ground station. The update frequency of the odometry seems enough fast (0.012454s ~ 80Hz).

The rtabmap node is processing pretty fast too (0.016682s ~ 60 Hz) on the beginning. Are you referring to the rtabmap's update rate of 1 second? 1 Hz is the default update rate of RTAB-Map. Well, in my experiments, 1 Hz is enough to get a satisfying 3D map without using too much computation power. However, you can still increase this rate using the parameter "Rtabmap/DetectionRate", for example to 2 Hz:

   <param name="Rtabmap/DetectionRate" type="string" value="2"/>

Note that rtabmap node computation time is not bounded if the time limit is not set (as in your configuration where "Limit=0.000000s"). So the time shown in "RTAB-Map=0.016682s" will eventually get over the update rate. If you increase "Rtabmap/DetectionRate", your system will not be online at some point. To set the time limit to keep the mapping node online, set the parameter "Rtabmap/TimeThr" too. Refer to this paper to know what are the consequences of setting this time limit. Here some examples depending on the detection rate:

   <param name="Rtabmap/DetectionRate" type="string" value="0.5"/> <!-- 2000 ms -->
   <param name="Rtabmap/TimeThr" type="string" value="1600"/>

   <param name="Rtabmap/DetectionRate" type="string" value="1"/> <!-- 1000 ms -->
   <param name="Rtabmap/TimeThr" type="string" value="700"/>

   <param name="Rtabmap/DetectionRate" type="string" value="2"/> <!-- 500 ms -->
   <param name="Rtabmap/TimeThr" type="string" value="400"/>

   <param name="Rtabmap/DetectionRate" type="string" value="5"/> <!-- 200 ms -->
   <param name="Rtabmap/TimeThr" type="string" value="150"/>

While I don't recommend it, but for testing, you can set "Rtabmap/DetectionRate" to 0 to make rtabmap node processing data as fast as it can.

cheers