A tutorial on how to sequentially match a data set

In this tutorial we are going to use the hannover data set for illustration. You can download the hannover data set from
slam6D -s 1 -e 65 -r 10 -i 100 -d 75 --epsICP=0.00001 home/dat/hannover1/

-s 1
This parameter is for specifying where the scan should start so the data set registration will start from the first scan.

-e 65
This parameter is for specifying where the scan should end so the registration is going to end after the 65th scan.

-r 10
This is the point reduction parameter. It will reduce the points to a voxel size of 10.

-i 100
This parameter specifies that there should be 100 iterations in the sequential matching.

-d 75
This parameter specifies that the maximal distance of points that may form corresponding point pairs is 75.

--epsICP=0.00001
Each iteration of the ICP algorithms minimizes the error between all point pairs. This parameter specifies one of the stopping criteria of the algorithm. If in subsequent iterations the difference of average distances between the point pairs after matching falls below this value, the matching process is terminated. The sequential matching of the data set contains some error. This parameter specifies the stopping criteria of the iteration. In this case, if the difference between two points is smaller than 0.00001, the iteration will stop.

/home/dat/hannover1/
This is the destination path for the folder containing the scans to be registered. This may vary depending on where you save the hannover1 data set.

To visualise or animate the data set you can refer to the show tutorials on this page. An example command for using show to graphically display the sequentially matched data set is:
show -s 1 -e 65
This will display the sequentially matched data set starting from the 1st scan and ending on the 65th scan.

Below are shots of the output generated by show for the sequentially matched data set.

Top view of sequentially matched data set

Top view showing overlapping wall of the sequentially matched data set

It can be seen from the second shot that there is an overlapping of the wall. This error can be removed by using simultaneous matching
to match the data set.

Related Publications

Informatics VII - Robotics and Telematics, Prof. Dr Andreas Nüchter, andreas (at) nuechti.de, Tel. +49-177-7951270