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30 // Author: Johannes L. Schoenberger (jsch-at-demuc-dot-de)
31 
32 #ifndef COLMAP_SRC_MVS_GPU_MAT_REF_IMAGE_H_
33 #define COLMAP_SRC_MVS_GPU_MAT_REF_IMAGE_H_
34 
35 #include <memory>
36 
37 #include "mvs/cuda_array_wrapper.h"
38 #include "mvs/gpu_mat.h"
39 
40 namespace colmap {
41 namespace mvs {
42 
43 class GpuMatRefImage {
44  public:
45   GpuMatRefImage(const size_t width, const size_t height);
46 
47   // Filter image using sum convolution kernel to compute local sum of
48   // intensities. The filtered images can then be used for repeated, efficient
49   // NCC computation.
50   void Filter(const uint8_t* image_data, const size_t window_radius,
51               const size_t window_step, const float sigma_spatial,
52               const float sigma_color);
53 
54   // Image intensities.
55   std::unique_ptr<GpuMat<uint8_t>> image;
56 
57   // Local sum of image intensities.
58   std::unique_ptr<GpuMat<float>> sum_image;
59 
60   // Local sum of squared image intensities.
61   std::unique_ptr<GpuMat<float>> squared_sum_image;
62 
63  private:
64   const static size_t kBlockDimX = 16;
65   const static size_t kBlockDimY = 12;
66 
67   size_t width_;
68   size_t height_;
69 };
70 
71 struct BilateralWeightComputer {
BilateralWeightComputerBilateralWeightComputer72   __device__ BilateralWeightComputer(const float sigma_spatial,
73                                      const float sigma_color)
74       : spatial_normalization_(1.0f / (2.0f * sigma_spatial * sigma_spatial)),
75         color_normalization_(1.0f / (2.0f * sigma_color * sigma_color)) {}
76 
ComputeBilateralWeightComputer77   __device__ inline float Compute(const float row_diff, const float col_diff,
78                                   const float color1,
79                                   const float color2) const {
80     const float spatial_dist_squared =
81         row_diff * row_diff + col_diff * col_diff;
82     const float color_dist = color1 - color2;
83     return exp(-spatial_dist_squared * spatial_normalization_ -
84                color_dist * color_dist * color_normalization_);
85   }
86 
87  private:
88   const float spatial_normalization_;
89   const float color_normalization_;
90 };
91 
92 }  // namespace mvs
93 }  // namespace colmap
94 
95 #endif  // COLMAP_SRC_MVS_GPU_MAT_REF_IMAGE_H_
96