Help Content > Basic Module > Ship Detection

Purpose

This tool allows detecting ships over water bodies derived by SAR images and match this information with the AIS (Automatic Identification System) information, if available. A doppler shift correction is performed on moving objects.

Technical Note

Only co-polarized images (VV, HH) are considered. The AIS format of the input files has to be defined between the supported NMEA and CSV formats. Please note: before starting to perform tool, it necessary to run the tool SAR Setting AIS CSV format in SARscape Management Tool to specify the column of the csv file in which the parameter is reported.

Input Files

Input AIS

Input file name of the AIS shape file containing vessels positions.

Input AIS Track

Input file name of the AIS shape file (plus .dbf and .shx) containing tracks of vessels. The attribute table contains following parameters (when available):

MMSI, Provider, Class, Time, IMONumber, CallSign, VesselName, ShipType, DimToBow, DimToStern, DimToPort, DimToStarb, ETA, Draught and Destination.

Input Detected Ship

Input shape file of the detected ships.

Please note: This feature is available only with geocoded input files. This shapefile and the geocoded input file must be in the same cartographic system/projection.

Input Geo SAR Image

Input file name of the SAR images (*_geo). Note: Only _geo files are currently supported. These files are mandatory.

Parameters - Principal Parameters

Use Custom Distance Threshold

By setting this flag the user will have the possibility to set a custom Distance Threshold.

Distance Threshold [m]

Maximum acceptable distance between a ship position and the corresponding ais track.

Offset Time Start [s]

Tracks starting after image acquisition will be discarded if track start time – sar time > offset_time_start.

Offset Time End [s]

Tracks ending before image acquisition will be discarded if sar time - track end time > offset_time_start.

Max Speed [m/s]

Maximum acceptable speed for a moving object. Speed is computed using consecutive AIS data, a threshold value helps preventing miscalculations caused by wrong AIS data.

Track Min Time [s]

Minimum time between consecutive AIS data in each track.

Parameters - Global

It brings to the general section of the Preferences parameters. Any modified value will be used and stored for further processing sessions.

Parameters - Other Parameters

It brings to the general section of the Preferences parameters. Any modified value will be used and stored for further processing sessions.

Output Files

_SAR.shp

Shape file showing ships detected but not matched with AIS data.

_AIS_matched.shp

Shape file showing tracks matched with a detected ship.

_AIS.shp

Shape file showing tracks without any match.

_SAR_AIS.shp

Shape file showing ships detected and matched with an AIS track.

_AIS_matched_short.shp

Shape file showing a short version of the matched tracks (these tracks are computed only with the 2 points which are the nearest to the corresponding ship position.)

General Functions

Exec

The processing step is executed.

Store Batch

The processing step is stored in the batch list. The Batch Browser button allows to load the batch processing list.

The window will be closed.

Help

Specific help document section.

Specific Function(s)

None.