Attribute VB_Name = "Module1"
Public a_ As Double
Public b_ As Double
Public c_ As Double
Public d_ As Double
Public e_ As Double
Public f_ As Double

Public Sub a_transform_affine(ByVal q As Integer, ByVal direction As Integer, x As Double, y As Double, p_x As Double, p_y As Double)
 Select Case direction
 Case 0   ' From camera coordinates to image cordinates (pixels)
 p_x = a_ * x + b_ * y + c_
 p_y = d_ * x + e_ * y + f_
 Case 1  ' From image coordinates (pixels) to camera cordinates (mm)
 p_x = (-e_ * c_ + e_ * x + f_ * b_ - y * b_) / (a_ * e_ - b_ * d_)
 p_y = -(a_ * f_ - a_ * y - c_ * d_ + x * d_) / (a_ * e_ - b_ * d_)
 End Select
End Sub
Public Function det_cal3(ByRef E() As Double) As Double
' This function calculates the determinant of a 3x3 matrix E
Dim term1 As Double, term2 As Double, term3 As Double, term4 As Double, term5 As Double, term6 As Double
term1 = E(1, 1) * E(2, 2) * E(3, 3)
term2 = E(2, 1) * E(3, 2) * E(1, 3)
term3 = E(3, 1) * E(1, 2) * E(2, 3)
term4 = E(1, 1) * E(3, 2) * E(2, 3)
term5 = E(2, 1) * E(1, 2) * E(3, 3)
term6 = E(3, 1) * E(2, 2) * E(1, 3)
det_cal3 = term1 + term2 + term3 - term4 - term5 - term6
End Function