Merge pull request #21095 from No-Plane-Cannot-Be-Detected:next_SIMD

Accelerated 3D point cloud Farthest Point Sampling calculation using SIMD.

* Add several 3D point cloud sampling functions: Random, VoxelGrid, FarthestPoint.

* Made some code detail changes and exposed the random number generator parameters at the interface.

* Add simple tests for sampling.

* Modify interface output parameters.

* Modify interface return value.

* The sampling test is modified for the new changes of function interface.

* Improved test of VoxelGridFilterSampling

* Improved test of VoxelGridFilterSampling and FPS.

* Add test for the dist_lower_limit arguments of FPS function.

* Optimization function _getMatFromInputArray.

* Optimize the code style and some details according to the suggestions.

* Clear prefix cv: in the source code.

* Change the initialization of Mat in the sampling test.

* 1. Unified code style
2. Optimize randomSampling method

* 1. Optimize code comments.
2. Remove unused local variables.

* Rebuild the structure of the test, make the test case more reliable, and change the code style.

* Update test_sampling.cpp

Fix a warning.

* Use SIMD to optimize the farthest point sampling.

* Optimize the farthest point sampling SIMD code.

* 1. remove `\n` from the ptcloud.hpp comment.
2. updated the default value of the argument arrangement_of_points in the _getMatFromInputArray function in ptcloud_utils.hpp from 0 to 1, since the latter is more commonly used (such arrangement is easier for SIMD acceleration).
3. removed two functions in ptcloud_utils.hpp that were not used.

* Remove the <br> in the comment.

* Fix whitespace issues.

modules/3d/include/opencv2/3d/ptcloud.hpp

@@ -18,7 +18,7 @@ namespace cv {
  * point cloud data, in each voxel (i.e., 3D box), all the points present will be
  * approximated (i.e., downsampled) with the point closest to their centroid.
  *
- * @param sampled_point_flags  (Output) Flags of the sampled point, (pass in std::vector<int> or std::vector<char> etc.)
+ * @param[out] sampled_point_flags  Flags of the sampled point, (pass in std::vector<int> or std::vector<char> etc.)
  *                     sampled_point_flags[i] is 1 means i-th point selected, 0 means it is not selected.
  * @param input_pts  Original point cloud, vector of Point3 or Mat of size Nx3/3xN.
  * @param length Grid length.
@@ -63,17 +63,17 @@ CV_EXPORTS void randomSampling(OutputArray sampled_pts, InputArray input_pts,
  * @brief Point cloud sampling by Farthest Point Sampling(FPS).
  *
  * FPS Algorithm:
- *   Input: Point cloud *C*, *sampled_pts_size*, *dist_lower_limit*
- *   Initialize: Set sampled point cloud S to the empty set
- *   Step:
+ * + Input: Point cloud *C*, *sampled_pts_size*, *dist_lower_limit*
+ * + Initialize: Set sampled point cloud S to the empty set
+ * + Step:
  *     1. Randomly take a seed point from C and take it from C to S;
  *     2. Find a point in C that is the farthest away from S and take it from C to S;
  *       (The distance from point to set S is the smallest distance from point to all points in S)
  *     3. Repeat *step 2* until the farthest distance of the point in C from S
  *       is less than *dist_lower_limit*, or the size of S is equal to *sampled_pts_size*.
- *   Output: Sampled point cloud S
+ * + Output: Sampled point cloud S
  *
- * @param sampled_point_flags  (Output) Flags of the sampled point, (pass in std::vector<int> or std::vector<char> etc.)
+ * @param[out] sampled_point_flags  Flags of the sampled point, (pass in std::vector<int> or std::vector<char> etc.)
  *                     sampled_point_flags[i] is 1 means i-th point selected, 0 means it is not selected.
  * @param input_pts  Original point cloud, vector of Point3 or Mat of size Nx3/3xN.
  * @param sampled_pts_size The desired point cloud size after sampling.
@@ -89,7 +89,7 @@ CV_EXPORTS int farthestPointSampling(OutputArray sampled_point_flags, InputArray
 /**
  * @overload
  *
- * @param sampled_point_flags  (Output) Flags of the sampled point, (pass in std::vector<int> or std::vector<char> etc.)
+ * @param[out] sampled_point_flags  Flags of the sampled point, (pass in std::vector<int> or std::vector<char> etc.)
  *                     sampled_point_flags[i] is 1 means i-th point selected, 0 means it is not selected.
  * @param input_pts  Original point cloud, vector of Point3 or Mat of size Nx3/3xN.
  * @param sampled_scale Range (0, 1), the percentage of the sampled point cloud to the original size,