1 /*
2  * Medical Image Registration ToolKit (MIRTK)
3  *
4  * Copyright 2013-2015 Imperial College London
5  * Copyright 2013-2015 Andreas Schuh
6  *
7  * Licensed under the Apache License, Version 2.0 (the "License");
8  * you may not use this file except in compliance with the License.
9  * You may obtain a copy of the License at
10  *
11  *     http://www.apache.org/licenses/LICENSE-2.0
12  *
13  * Unless required by applicable law or agreed to in writing, software
14  * distributed under the License is distributed on an "AS IS" BASIS,
15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16  * See the License for the specific language governing permissions and
17  * limitations under the License.
18  */
19 
20 #ifndef MIRTK_VelocityToDisplacementFieldEuler_H
21 #define MIRTK_VelocityToDisplacementFieldEuler_H
22 
23 #include "mirtk/VelocityToDisplacementField.h"
24 
25 
26 namespace mirtk {
27 
28 
29 // Vector field interpolator
30 class InterpolateImageFunction;
31 
32 
33 /**
34  * Computes a displacement field from a stationary velocity field.
35  *
36  * This class implements an image filter which computes the exponential map
37  * of a stationary velocity field using the forward Euler integration method.
38  * The result is a diffeomorphic displacement field.
39  */
40 template <class TVoxel>
41 class VelocityToDisplacementFieldEuler : public VelocityToDisplacementField<TVoxel>
42 {
43   mirtkImageFilterMacro(VelocityToDisplacementFieldEuler, TVoxel);
44 
45 protected:
46 
47   /// Image function for interpolation of velocities
48   InterpolateImageFunction *_VelocityInterpolator;
49 
50   /// Initialize filter
51   virtual void Initialize();
52 
53 public:
54 
55   /// Constructor
56   VelocityToDisplacementFieldEuler();
57 
58   /// Destructor
59   virtual ~VelocityToDisplacementFieldEuler();
60 
61   /// Compute output = log(input)
62   virtual void Run();
63 
64 };
65 
66 
67 } // namespace mirtk
68 
69 #endif // MIRTK_VelocityToDisplacementFieldEuler_H
70