GOCADeformationanalysisConcept
The GOCASoftware is designed for the classical type of an absolute deformationnetwork, i.e. that the objects
geometry is described in a coordinatesystem, which is not influenced by the deformationprocess. This coordinatesystem is represented by
reference points in the stable area. The measurments at different time (epochs) provide the information for the
respective absolute epochcoordinates of the objectpoints in the deformable area.
To ensure a stable referencesystem for each trackingintervall, the qualityassuranceconcept of GOCA includes the
detection of instable referencepoints based on a deformationanalysis in an observationrelated approach.


Observations in GOCA are the threedimensional baselinevectors, distance or anglemeasurements with thier covariancematrix related to one ore more GNSSBase or TPSStation(s). These observations are transformed, in case of GNSSObservations, in twodimensional plan and onedimensional heightbaselines with consideration of the law of errorpropagation. TPSObservations are reduced to a projection ellipsoid. If necessary, heightintegrationparameters are calculated with shared GNSS/TPS points. Are one ore more GNSSBase or TPSStations detected to be unstable when checking the reference points, their coordinates have to be introduced in the following as unknowns during the estimation of object point coordinates by means of leastsquaresadjustment. Therefore it is not necessary to set up the GNSSBase or TPSStations in the stable area of the deformation network. 

As sensorcomponents of a GOCA array, GNSSsensors, total stations and levelingsensors can be used as well as geotechnical sensors.
A communication and hardwarecontrolsofware based on the GKAdatainterface is responsible for the communication between GOCAdefomrationanalysissoftware and the sensorcomponent. For GNSS and TPSSensors, the modules GOCAGNSSControl and GOCATPSControl are available. The GOCAsoftware does  besides the initialisation, georeferencing and checking of stablepoints  a deformationanalysis (trend estimation, kalmanfiltering, FEM) with respct to the objectpoints participating at the monitoring. Over and above that an alarmmanagement and a deformationprediction is provided by the GOCASoftware. 