1. Overview

This page describes the circle selection algorithm while calculating results from the Apollonius (AP) method. Details of the AP method can be found here.

2. Objective

The AP method provides multiple results (in the form of a solution set) when calculating the target location using RTT measurements from landmarks. At the moment we manually select the most appropriate result (by comparing the results with geo-ip lat and log records).

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For results please see the attachments.

Conclusion:

The cluster based approach takes one circle as the AP circle and the final coordinates are calculated on the basis of this circle. The manual approach of using all the circles for calculating latitude and longitude, uses all the circles, so the cluster approach can theoretically (if the Geo IP result is correct) perform equal to the manual approach only in the best case scenario.

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A comparison of the accuracies yielded by the two methods as applied to 74 targets in 46 countries is seen below (also see the spreadsheet ):

It is seen that there is little difference with the manual method in general being slightly better.

Cluster Method
Manual Method Comparison Graph of both techniques

Reference

Apollonius and its PerformanceTODO:
Add description page of Apollonius
Add page describing landmark selection method.