Using ELKI MiniGUI to create spatial KNN for spatial outlier detection of attribute values.‏

Question

I'm having difficulties using the ELKI MiniGUI to run spatial outlier detection algorithms. Many of the algorithms require a list of KNN for each object in the database. It appears that a KNN label list first needs to be created from the spatial coordinate database only, not including the attributes. Then, I suppose the spatial outlier detection algorithms are run on the attribute database along with the external file of the spatial KNN.

My Java experience is limited, so I would like to use ELKI in the command line and use the MiniGUI to assemble code for each task. However, with the MiniGUI I have only been able to create, or materialize, external files for 1) the triangular distance matrix and 2) the KNN Distance Order, which seems to include the object itself as one of the KNN. It seems that I really need an external file, or cached data, of a list of each object and their spatial neighbors. Maybe a KNN Query, KNN Join, precomputed distances or preprocessed database filter would be helpful, but I really don't know.

What steps are needed to create and use files, or cached data, that are required to supply the KNN spatial relation for the spatial outlier detection attribute relation of each object to its neighbors? I am unclear of how to do this with the MiniGUI, especially since it looks like the spatial neighborhood relation needs to be created first, before using it with the spatial outlier detection algorithm and the attribute database.

Any advice is greatly appreciated.

Thanks!

Answer 1

Thank you for contributing a how-to to the ELKI wiki!

How to perform geo-spatial outlier detection with an external neighborhood specification

it is a nice step-by-step introduction to using ELKI, and I hope others will find it useful.

Posting as "answer" here, so that others have it easy to find.