DepthPerception.py

import math
import vtk
from PythonMetricsCalculator import PerkEvaluatorMetric

class DepthPerception( PerkEvaluatorMetric ):

 # Static methods
 @staticmethod
 def GetMetricName():
 return "Depth Perception"
 
 @staticmethod 
 def GetMetricUnit():
 return "mm"
 
 @staticmethod
 def GetTransformRoles():
 return [ "Needle" ]
 
 
 # Instance methods 
 def __init__( self ):
 PerkEvaluatorMetric.__init__( self )
 
 self.depthPerception = 0 
 self.pointPrev = None 
 
 def AddTimestamp( self, time, matrix, point, role ):
 if ( self.pointPrev == None ):
 self.pointPrev = point[:]
 
 # Find the prev to current vector
 prevToCurrentVector = [ 0, 0, 0 ]
 vtk.vtkMath().Subtract( point[0:3], self.pointPrev[0:3], prevToCurrentVector )
 prevToCurrentVector = [ prevToCurrentVector[ 0 ], prevToCurrentVector[ 1 ], prevToCurrentVector[ 2 ] ]
 
 # Compute the direction vector of the needle in RAS, using the needle orientation protocol
 needleOrientation = self.NeedleOrientation[:]
 needleOrientation.append( 0 )
 needleVector_RAS = [ 0, 0, 0, 0 ]
 matrix.MultiplyPoint( needleOrientation, needleVector_RAS )
 
 # Find the movement in the needle direction
 needleAxisMovement = vtk.vtkMath().Dot( prevToCurrentVector, needleVector_RAS[ 0:3 ] )
 
 self.depthPerception += math.fabs( needleAxisMovement )
 
 self.pointPrev = point[:]
 
 def GetMetric( self ):
 return self.depthPerception