Point Cloud Library (PCL)  1.7.0
random_sample.hpp
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34  * $Id: extract_indices.hpp 1897 2011-07-26 20:35:49Z rusu $
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37 
38 #ifndef PCL_FILTERS_IMPL_RANDOM_SAMPLE_H_
39 #define PCL_FILTERS_IMPL_RANDOM_SAMPLE_H_
40 
41 #include <pcl/filters/random_sample.h>
42 #include <pcl/common/io.h>
43 #include <pcl/point_traits.h>
44 
45 
46 ///////////////////////////////////////////////////////////////////////////////
47 template<typename PointT> void
49 {
50  std::vector<int> indices;
51  if (keep_organized_)
52  {
53  bool temp = extract_removed_indices_;
54  extract_removed_indices_ = true;
55  applyFilter (indices);
56  extract_removed_indices_ = temp;
57  copyPointCloud (*input_, output);
58  // Get X, Y, Z fields
59  std::vector<pcl::PCLPointField> fields;
60  pcl::getFields (*input_, fields);
61  std::vector<size_t> offsets;
62  for (size_t i = 0; i < fields.size (); ++i)
63  {
64  if (fields[i].name == "x" ||
65  fields[i].name == "y" ||
66  fields[i].name == "z")
67  offsets.push_back (fields[i].offset);
68  }
69  // For every "removed" point, set the x,y,z fields to user_filter_value_
70  const static float user_filter_value = user_filter_value_;
71  for (size_t rii = 0; rii < removed_indices_->size (); ++rii)
72  {
73  uint8_t* pt_data = reinterpret_cast<uint8_t*> (&output[(*removed_indices_)[rii]]);
74  for (size_t i = 0; i < offsets.size (); ++i)
75  {
76  memcpy (pt_data + offsets[i], &user_filter_value, sizeof (float));
77  }
78  if (!pcl_isfinite (user_filter_value_))
79  output.is_dense = false;
80  }
81  }
82  else
83  {
84  output.is_dense = true;
85  applyFilter (indices);
86  copyPointCloud (*input_, indices, output);
87  }
88 }
89 
90 ///////////////////////////////////////////////////////////////////////////////
91 template<typename PointT>
92 void
93 pcl::RandomSample<PointT>::applyFilter (std::vector<int> &indices)
94 {
95  unsigned N = static_cast<unsigned> (indices_->size ());
96 
97  unsigned int sample_size = negative_ ? N - sample_ : sample_;
98  // If sample size is 0 or if the sample size is greater then input cloud size
99  // then return all indices
100  if (sample_size >= N)
101  {
102  indices = *indices_;
103  removed_indices_->clear ();
104  }
105  else
106  {
107  // Resize output indices to sample size
108  indices.resize (static_cast<size_t> (sample_size));
109  if (extract_removed_indices_)
110  removed_indices_->resize (static_cast<size_t> (N - sample_size));
111 
112  // Set random seed so derived indices are the same each time the filter runs
113  std::srand (seed_);
114 
115  // Algorithm A
116  unsigned top = N - sample_size;
117  unsigned i = 0;
118  unsigned index = 0;
119  std::vector<bool> added;
120  if (extract_removed_indices_)
121  added.resize (indices_->size (), false);
122  for (size_t n = sample_size; n >= 2; n--)
123  {
124  float V = unifRand ();
125  unsigned S = 0;
126  float quot = static_cast<float> (top) / static_cast<float> (N);
127  while (quot > V)
128  {
129  S++;
130  top--;
131  N--;
132  quot = quot * static_cast<float> (top) / static_cast<float> (N);
133  }
134  index += S;
135  if (extract_removed_indices_)
136  added[index] = true;
137  indices[i++] = (*indices_)[index++];
138  N--;
139  }
140 
141  index += N * static_cast<unsigned> (unifRand ());
142  if (extract_removed_indices_)
143  added[index] = true;
144  indices[i++] = (*indices_)[index++];
145 
146  // Now populate removed_indices_ appropriately
147  if (extract_removed_indices_)
148  {
149  unsigned ri = 0;
150  for (size_t i = 0; i < added.size (); i++)
151  {
152  if (!added[i])
153  {
154  (*removed_indices_)[ri++] = (*indices_)[i];
155  }
156  }
157  }
158  }
159 }
160 
161 #define PCL_INSTANTIATE_RandomSample(T) template class PCL_EXPORTS pcl::RandomSample<T>;
162 
163 #endif // PCL_FILTERS_IMPL_RANDOM_SAMPLE_H_