--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Toolbox/ShearWarpProjectiveTransform.cpp	Fri Mar 16 15:01:52 2018 +0100
@@ -0,0 +1,329 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2018 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Affero General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Affero General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#include "ShearWarpProjectiveTransform.h"
+
+#include "ImageGeometry.h"
+#include "Extent2D.h"
+#include "FiniteProjectiveCamera.h"
+#include "GeometryToolbox.h"
+
+#include <Core/OrthancException.h>
+#include <Core/Logging.h>
+
+#include <boost/numeric/ublas/matrix_proxy.hpp>
+#include <cassert>
+
+
+namespace OrthancStone
+{
+  static bool IsValidShear(const Matrix& M_shear)
+  {
+    return (LinearAlgebra::IsCloseToZero(M_shear(0, 1)) &&
+            LinearAlgebra::IsCloseToZero(M_shear(1, 0)) &&
+            LinearAlgebra::IsCloseToZero(M_shear(2, 0)) &&
+            LinearAlgebra::IsCloseToZero(M_shear(2, 1)) &&
+            LinearAlgebra::IsNear(1.0,   M_shear(2, 2)) &&
+            LinearAlgebra::IsCloseToZero(M_shear(2, 3)) &&
+            LinearAlgebra::IsCloseToZero(M_shear(3, 0)) &&
+            LinearAlgebra::IsCloseToZero(M_shear(3, 1)) &&
+            LinearAlgebra::IsNear(1.0,   M_shear(3, 3)));
+  }
+
+
+  static void ComputeShearParameters(double& scaling,
+                                     double& offsetX,
+                                     double& offsetY,
+                                     const Matrix& shear,
+                                     double z)
+  {
+    // Check out: ../../Resources/Computations/ComputeShearParameters.py
+    
+    if (!LinearAlgebra::IsShearMatrix(shear))
+    {
+      LOG(ERROR) << "Not a valid shear matrix";
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+    }
+    
+    scaling = 1.0 / (shear(3,2) * z + 1.0);
+    offsetX = shear(0,2) * z * scaling;
+    offsetY = shear(1,2) * z * scaling;
+  }  
+
+
+  ShearWarpProjectiveTransform::
+  ShearWarpProjectiveTransform(const Matrix& M_view,
+                               //const Matrix& P,           // Permutation applied to the volume
+                               unsigned int volumeWidth,
+                               unsigned int volumeHeight,
+                               unsigned int volumeDepth,
+                               double pixelSpacingX,
+                               double pixelSpacingY,
+                               unsigned int imageWidth,
+                               unsigned int imageHeight)
+  {
+    eye_o.resize(4);
+
+    {
+      // Find back the camera center given the "M_view" matrix
+      const double m11 = M_view(0, 0);
+      const double m12 = M_view(0, 1);
+      const double m13 = M_view(0, 2);
+      const double m14 = M_view(0, 3);
+      const double m21 = M_view(1, 0);
+      const double m22 = M_view(1, 1);
+      const double m23 = M_view(1, 2);
+      const double m24 = M_view(1, 3);
+      const double m41 = M_view(3, 0);
+      const double m42 = M_view(3, 1);
+      const double m43 = M_view(3, 2);
+      const double m44 = M_view(3, 3);
+
+      // Equations (A.8) to (A.11) on page 203. Also check out
+      // "Finding the camera center" in "Multiple View Geometry in
+      // Computer Vision - 2nd edition", page 163.
+      const double vx[9] = { m12, m13, m14, m22, m23, m24, m42, m43, m44 };
+      const double vy[9] = { m11, m13, m14, m21, m23, m24, m41, m43, m44 };
+      const double vz[9] = { m11, m12, m14, m21, m22, m24, m41, m42, m44 };
+      const double vw[9] = { m11, m12, m13, m21, m22, m23, m41, m42, m43 };
+
+      Matrix m;
+
+      LinearAlgebra::FillMatrix(m, 3, 3, vx);
+      eye_o[0] = -LinearAlgebra::ComputeDeterminant(m);
+
+      LinearAlgebra::FillMatrix(m, 3, 3, vy);
+      eye_o[1] = LinearAlgebra::ComputeDeterminant(m);
+
+      LinearAlgebra::FillMatrix(m, 3, 3, vz);
+      eye_o[2] = -LinearAlgebra::ComputeDeterminant(m);
+
+      LinearAlgebra::FillMatrix(m, 3, 3, vw);
+      eye_o[3] = LinearAlgebra::ComputeDeterminant(m);
+
+      if (LinearAlgebra::IsCloseToZero(eye_o[3]))
+      {
+        LOG(ERROR) << "The shear-warp projective transform is not applicable to affine cameras";
+        throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+      }
+    }
+
+#if 0
+    // Assume "T_shift = I" (the eye does not lie on plane k = 0)
+    const Matrix T_shift = LinearAlgebra::IdentityMatrix(4);
+    
+    // Equation (A.13) on page 204, given that the inverse of a
+    // permutation matrix is its transpose (TODO CHECK). If no T_shift
+    // or permutation P is applied, M'_view == M_view
+    const Matrix MM_view = LinearAlgebra::Product(
+      M_view,
+      LinearAlgebra::Transpose(P),
+      LinearAlgebra::InvertScalingTranslationMatrix(T_shift));
+#else
+    // This is a shortcut, as we take "T_shift = I" and "P = I"
+    const Matrix MM_view = M_view;
+#endif
+
+    // Equation (A.14) on page 207
+    Matrix MM_shear = LinearAlgebra::IdentityMatrix(4);
+    MM_shear(0, 2) = -eye_o[0] / eye_o[2];
+    MM_shear(1, 2) = -eye_o[1] / eye_o[2];
+    MM_shear(3, 2) = -eye_o[3] / eye_o[2];
+
+
+    // Compute the extent of the intermediate image
+    Extent2D extent;
+    double maxScaling = 1;
+
+    {
+      // Compute the shearing factors of the two extreme planes of the
+      // volume (z=0 and z=volumeDepth)
+      double scaling, offsetX, offsetY;
+      ComputeShearParameters(scaling, offsetX, offsetY, MM_shear, 0);
+
+      if (scaling > 0)
+      {
+        extent.AddPoint(offsetX, offsetY);
+        extent.AddPoint(offsetX + static_cast<double>(volumeWidth) * scaling,
+                        offsetY + static_cast<double>(volumeHeight) * scaling);
+
+        if (scaling > maxScaling)
+        {
+          maxScaling = scaling;
+        }
+      }
+
+      ComputeShearParameters(scaling, offsetX, offsetY, MM_shear, volumeDepth);
+
+      if (scaling > 0)
+      {
+        extent.AddPoint(offsetX, offsetY);
+        extent.AddPoint(offsetX + static_cast<double>(volumeWidth) * scaling,
+                        offsetY + static_cast<double>(volumeHeight) * scaling);
+
+        if (scaling > maxScaling)
+        {
+          maxScaling = scaling;
+        }
+      }
+    }
+      
+    if (LinearAlgebra::IsCloseToZero(extent.GetWidth()) ||
+        LinearAlgebra::IsCloseToZero(extent.GetHeight()))
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+    }
+
+    intermediateWidth_ = std::ceil(extent.GetWidth() / maxScaling);
+    intermediateHeight_ = std::ceil(extent.GetHeight() / maxScaling);
+
+    // This is the product "T * S" in Equation (A.16) on page 209
+    Matrix TS = LinearAlgebra::Product(
+      GeometryToolbox::CreateTranslationMatrix(static_cast<double>(intermediateWidth_) / 2.0,
+                                               static_cast<double>(intermediateHeight_) / 2.0, 0),
+      GeometryToolbox::CreateScalingMatrix(1.0 / maxScaling, 1.0 / maxScaling, 1),
+      GeometryToolbox::CreateTranslationMatrix(-extent.GetCenterX(), -extent.GetCenterY(), 0));
+    
+    // This is Equation (A.16) on page 209. WARNING: There is an
+    // error in Lacroute's thesis: "inv(MM_shear)" is used instead
+    // of "MM_shear".
+    M_shear = LinearAlgebra::Product(TS, MM_shear);
+
+    if (!IsValidShear(M_shear))
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+    }
+
+    // This is Equation (A.17) on page 209
+    Matrix tmp;
+    LinearAlgebra::InvertMatrix(tmp, M_shear);
+    M_warp = LinearAlgebra::Product(MM_view, tmp);
+
+    // Intrinsic parameters of the camera
+    k_ = LinearAlgebra::ZeroMatrix(3, 4);
+    k_(0, 0) = 1.0 / pixelSpacingX;
+    k_(0, 3) = static_cast<double>(imageWidth) / 2.0;
+    k_(1, 1) = 1.0 / pixelSpacingY;
+    k_(1, 3) = static_cast<double>(imageHeight) / 2.0;
+    k_(2, 3) = 1.0;
+  }
+
+
+  FiniteProjectiveCamera *ShearWarpProjectiveTransform::CreateCamera() const
+  {
+    Matrix p = LinearAlgebra::Product(k_, M_warp, M_shear);
+    return new FiniteProjectiveCamera(p);
+  }
+  
+
+  void ShearWarpProjectiveTransform::ComputeShearOnSlice(double& a11,
+                                                         double& b1,
+                                                         double& a22,
+                                                         double& b2,
+                                                         double& shearedZ,
+                                                         const double sourceZ)
+  {
+    // Check out: ../../Resources/Computations/ComputeShearOnSlice.py
+    assert(IsValidShear(M_shear));
+
+    const double s11 = M_shear(0, 0);
+    const double s13 = M_shear(0, 2);
+    const double s14 = M_shear(0, 3);
+    const double s22 = M_shear(1, 1);
+    const double s23 = M_shear(1, 2);
+    const double s24 = M_shear(1, 3);
+    const double s43 = M_shear(3, 2);
+
+    double scaling = 1.0 / (s43 * sourceZ + 1.0);
+    shearedZ = sourceZ * scaling;
+
+    a11 = s11 * scaling;
+    a22 = s22 * scaling;
+
+    b1 = (s13 * sourceZ + s14) * scaling;
+    b2 = (s23 * sourceZ + s24) * scaling;
+  }
+
+
+  Matrix ShearWarpProjectiveTransform::CalibrateView(const Vector& camera,
+                                                     const Vector& principalPoint,
+                                                     double angle)
+  {
+    if (camera.size() != 3 ||
+        principalPoint.size() != 3)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_ParameterOutOfRange);
+    }
+
+    const double sid = boost::numeric::ublas::norm_2(camera - principalPoint);
+      
+    Matrix a;
+    GeometryToolbox::AlignVectorsWithRotation(a, camera - principalPoint,
+                                              LinearAlgebra::CreateVector(0, 0, -1));
+
+    Matrix r = LinearAlgebra::Product(GeometryToolbox::CreateRotationMatrixAlongZ(angle), a);
+
+    a = LinearAlgebra::ZeroMatrix(4, 4);
+    boost::numeric::ublas::subrange(a, 0, 3, 0, 3) = r;
+
+    const Vector v = LinearAlgebra::Product(r, -camera);
+    a(0, 3) = v[0];
+    a(1, 3) = v[1];
+    a(2, 3) = v[2];
+    a(3, 3) = 1;
+
+    Matrix perspective = LinearAlgebra::ZeroMatrix(4, 4);
+    // https://stackoverflow.com/questions/5267866/calculation-of-a-perspective-transformation-matrix
+    perspective(0, 0) = sid;
+    perspective(1, 1) = sid;
+    perspective(2, 2) = sid;
+    perspective(3, 2) = 1;
+
+    Matrix M_view = LinearAlgebra::Product(perspective, a);
+    assert(M_view.size1() == 4 &&
+           M_view.size2() == 4);
+
+    {
+      // Sanity checks
+      Vector p1 = LinearAlgebra::CreateVector(camera[0], camera[1], camera[2], 1.0);
+      Vector p2 = LinearAlgebra::CreateVector(principalPoint[0], principalPoint[1], principalPoint[2], 1.0);
+      
+      Vector v1 = LinearAlgebra::Product(M_view, p1);
+      Vector v2 = LinearAlgebra::Product(M_view, p2);
+
+      if (!LinearAlgebra::IsCloseToZero(v1[3]) ||  // Must be mapped to singularity (w=0)
+          LinearAlgebra::IsCloseToZero(v2[3]))
+      {
+        throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+      }
+
+      // The principal point must be mapped to (0,0,z,1)
+      v2 /= v2[3];
+      if (!LinearAlgebra::IsCloseToZero(v2[0]) ||
+          !LinearAlgebra::IsCloseToZero(v2[1]))
+      {
+        throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+      }      
+    }
+
+    return M_view;
+  }
+}