Convoy Analysis

Specify Parameters

Enter the Vehicle Registration Marks (VRMs) of the target vehicles that you want to analyze; they can be entered individually or you can use a list stored in a text file (perhaps generated as a result of Geographical Profiling for example).

Enter the VRMs in the Target VRMs box, one VRM per line separated by a carriage return. Alternatively click the Browse button to retrieve VRMs from a text file.

Select the date and time boundaries for the Plate Analysis records to be searched. The date and time range relates to the times that target vehicles are recorded in an ALPR read. Set a start and end date and time.

If you only want to consider a certain period each day, for example you may want to analyze Plate Analysis records between 09:00 and 09:30 each day, turn on the Include records only within these times checkbox and set the From and To times below.

Finally set the following options:

Time Window

Set the time window that defines a co-occurrence. For example, if you set a time window of 10 seconds (the default), it means that vehicles recorded as passing an ALPR camera within plus or minus 10 seconds of a target vehicle are considered to be in convoy. A range of values, up to 5 minutes is available. The larger the time window, the more results you are likely to get.

Minimum Co-occurrences

Set the minimum number of co-occurrences that you want to consider for each target vehicle. For example, setting the number to 2 means that you only want results where the vehicle has been in convoy with a target vehicle on more than one occasion. You can set any number between 1 and 10000, although a higher setting can reduce the number of results.

Ranked VRMs

You can choose to see all results by selecting All, or you can specify a Number of results to see. For example if you set the number to 10, you will only see the top ten ranked co-occurring vehicles, sorted by the number of co-occurrences.

Examine Co-Occurrences

This screen allows you to see how many co-occurrences have been detected; each co-occurring vehicle is listed along with the number of co-occurrences. If you have no results, or too many, you can go back and change the parameters by clicking the Back button.

You can see the Plate Analysis records relating to the convoy by selecting one or more groups of results, and clicking the Show Records button.

Note: If you select a result with five co-occurrences for example, when you show the records you will see ten records; for each co-occurrence you will see the Plate Analysis records for both the target and co-occurring vehicle.

Select one or more of the co-occurrences that you want to analyze in the grid view. When you have selected the results, click Next to go to the grid view.

Create a Grid Display

Co-occurrences for each target vehicle are displayed on a grid. The best way to understand the display is to consider this example. There are three target vehicles with the VRMs P2 DCM, F576 SQZ, and HH18 CLK. Each target has a tabbed page showing all the co-occurrences that relate to that vehicle. The table below represents the tabbed page for P2 DCM.

The first column of the grid shows the date and time that the target vehicle was recorded by an ALPR camera (this only shows the times that the target vehicle was recorded as a part of a co-occurrence, the vehicle may have been detected on many other occasions, but only co-occurrences are shown here).

The second column, headed with the target vehicle VRM, shows the name of the camera that recorded the read and shows the time that the target vehicle passed the camera.

The third column, headed with 'MJ75 LRV', shows the camera name that recorded a co-occurrence and the time (in seconds) relative to the target vehicle. The first entry in the third column shows that MJ75 LRV passed Camera 1 one second after the target vehicle. (If the time had been shown as -1, it would show that the target vehicle was recorded after MJ75 LRV.)

Each co-occurring vehicle has its own column; those shown with a bold heading, 'F576 SQZ' and 'HH18 CLK' in the example above, are themselves target vehicles; and they have their own tabbed pages.

You can copy the results for the current grid to the clipboard by clicking the Copy to clipboard button. Alternatively you can copy the results for all grids by turning on the Copy all grids checkbox before clicking the Copy to clipboard button.

From the clipboard, you can paste the results into another application such as a spreadsheet or text editor.