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osrm-backend/DataStructures/StaticRTree.h
DennisOSRM 0367399c89 Partial refactoring
2013-07-22 16:32:19 +02:00

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/*
open source routing machine
Copyright (C) Dennis Luxen, others 2010
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
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 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, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
or see http://www.gnu.org/licenses/agpl.txt.
*/
#ifndef STATICRTREE_H_
#define STATICRTREE_H_
#include "MercatorUtil.h"
#include "TimingUtil.h"
#include "Coordinate.h"
#include "PhantomNodes.h"
#include "DeallocatingVector.h"
#include "HilbertValue.h"
#include "../typedefs.h"
#include <boost/assert.hpp>
#include <boost/bind.hpp>
#include <boost/foreach.hpp>
#include <boost/algorithm/minmax.hpp>
#include <boost/algorithm/minmax_element.hpp>
#include <boost/range/algorithm_ext/erase.hpp>
#include <boost/noncopyable.hpp>
#include <boost/thread.hpp>
#include <cassert>
#include <cfloat>
#include <climits>
#include <algorithm>
#include <fstream>
#include <queue>
#include <string>
#include <vector>
//tuning parameters
const static uint32_t RTREE_BRANCHING_FACTOR = 50;
const static uint32_t RTREE_LEAF_NODE_SIZE = 1170;
// Implements a static, i.e. packed, R-tree
static boost::thread_specific_ptr<std::ifstream> thread_local_rtree_stream;
template<class DataT>
class StaticRTree : boost::noncopyable {
private:
struct RectangleInt2D {
RectangleInt2D() :
min_lon(INT_MAX),
max_lon(INT_MIN),
min_lat(INT_MAX),
max_lat(INT_MIN) {}
int32_t min_lon, max_lon;
int32_t min_lat, max_lat;
inline void InitializeMBRectangle(
const DataT * objects,
const uint32_t element_count
) {
for(uint32_t i = 0; i < element_count; ++i) {
min_lon = std::min(
min_lon, std::min(objects[i].lon1, objects[i].lon2)
);
max_lon = std::max(
max_lon, std::max(objects[i].lon1, objects[i].lon2)
);
min_lat = std::min(
min_lat, std::min(objects[i].lat1, objects[i].lat2)
);
max_lat = std::max(
max_lat, std::max(objects[i].lat1, objects[i].lat2)
);
}
}
inline void AugmentMBRectangle(const RectangleInt2D & other) {
min_lon = std::min(min_lon, other.min_lon);
max_lon = std::max(max_lon, other.max_lon);
min_lat = std::min(min_lat, other.min_lat);
max_lat = std::max(max_lat, other.max_lat);
}
inline _Coordinate Centroid() const {
_Coordinate centroid;
//The coordinates of the midpoints are given by:
//x = (x1 + x2) /2 and y = (y1 + y2) /2.
centroid.lon = (min_lon + max_lon)/2;
centroid.lat = (min_lat + max_lat)/2;
return centroid;
}
inline bool Intersects(const RectangleInt2D & other) const {
_Coordinate upper_left (other.max_lat, other.min_lon);
_Coordinate upper_right(other.max_lat, other.max_lon);
_Coordinate lower_right(other.min_lat, other.max_lon);
_Coordinate lower_left (other.min_lat, other.min_lon);
return (
Contains(upper_left)
|| Contains(upper_right)
|| Contains(lower_right)
|| Contains(lower_left)
);
}
inline double GetMinDist(const _Coordinate & location) const {
bool is_contained = Contains(location);
if (is_contained) {
return 0.0;
}
double min_dist = DBL_MAX;
min_dist = std::min(
min_dist,
ApproximateDistance(
location.lat,
location.lon,
max_lat,
min_lon
)
);
min_dist = std::min(
min_dist,
ApproximateDistance(
location.lat,
location.lon,
max_lat,
max_lon
)
);
min_dist = std::min(
min_dist,
ApproximateDistance(
location.lat,
location.lon,
min_lat,
max_lon
)
);
min_dist = std::min(
min_dist,
ApproximateDistance(
location.lat,
location.lon,
min_lat,
min_lon
)
);
return min_dist;
}
inline double GetMinMaxDist(const _Coordinate & location) const {
double min_max_dist = DBL_MAX;
//Get minmax distance to each of the four sides
_Coordinate upper_left (max_lat, min_lon);
_Coordinate upper_right(max_lat, max_lon);
_Coordinate lower_right(min_lat, max_lon);
_Coordinate lower_left (min_lat, min_lon);
min_max_dist = std::min(
min_max_dist,
std::max(
ApproximateDistance(location, upper_left ),
ApproximateDistance(location, upper_right)
)
);
min_max_dist = std::min(
min_max_dist,
std::max(
ApproximateDistance(location, upper_right),
ApproximateDistance(location, lower_right)
)
);
min_max_dist = std::min(
min_max_dist,
std::max(
ApproximateDistance(location, lower_right),
ApproximateDistance(location, lower_left )
)
);
min_max_dist = std::min(
min_max_dist,
std::max(
ApproximateDistance(location, lower_left ),
ApproximateDistance(location, upper_left )
)
);
return min_max_dist;
}
inline bool Contains(const _Coordinate & location) const {
bool lats_contained =
(location.lat > min_lat) && (location.lat < max_lat);
bool lons_contained =
(location.lon > min_lon) && (location.lon < max_lon);
return lats_contained && lons_contained;
}
inline friend std::ostream & operator<< (
std::ostream & out,
const RectangleInt2D & rect
) {
out << rect.min_lat/100000. << ","
<< rect.min_lon/100000. << " "
<< rect.max_lat/100000. << ","
<< rect.max_lon/100000.;
return out;
}
};
typedef RectangleInt2D RectangleT;
struct WrappedInputElement {
explicit WrappedInputElement(
const uint32_t _array_index,
const uint64_t _hilbert_value
) : m_array_index(_array_index), m_hilbert_value(_hilbert_value) {}
WrappedInputElement() : m_array_index(UINT_MAX), m_hilbert_value(0) {}
uint32_t m_array_index;
uint64_t m_hilbert_value;
inline bool operator<(const WrappedInputElement & other) const {
return m_hilbert_value < other.m_hilbert_value;
}
};
struct LeafNode {
LeafNode() : object_count(0) {}
uint32_t object_count;
DataT objects[RTREE_LEAF_NODE_SIZE];
};
struct TreeNode {
TreeNode() : child_count(0), child_is_on_disk(false) {}
RectangleT minimum_bounding_rectangle;
uint32_t child_count:31;
bool child_is_on_disk:1;
uint32_t children[RTREE_BRANCHING_FACTOR];
};
struct QueryCandidate {
explicit QueryCandidate(
const uint32_t n_id,
const double dist
) : node_id(n_id), min_dist(dist) {}
QueryCandidate() : node_id(UINT_MAX), min_dist(DBL_MAX) {}
uint32_t node_id;
double min_dist;
inline bool operator<(const QueryCandidate & other) const {
return min_dist < other.min_dist;
}
};
std::vector<TreeNode> m_search_tree;
uint64_t m_element_count;
const std::string m_leaf_node_filename;
public:
//Construct a packed Hilbert-R-Tree with Kamel-Faloutsos algorithm [1]
explicit StaticRTree(
std::vector<DataT> & input_data_vector,
const std::string tree_node_filename,
const std::string leaf_node_filename
)
: m_element_count(input_data_vector.size()),
m_leaf_node_filename(leaf_node_filename)
{
INFO("constructing r-tree of " << m_element_count << " elements");
double time1 = get_timestamp();
std::vector<WrappedInputElement> input_wrapper_vector(m_element_count);
//generate auxiliary vector of hilbert-values
#pragma omp parallel for schedule(guided)
for(uint64_t element_counter = 0; element_counter < m_element_count; ++element_counter) {
input_wrapper_vector[element_counter].m_array_index = element_counter;
//Get Hilbert-Value for centroid in mercartor projection
DataT & current_element = input_data_vector[element_counter];
_Coordinate current_centroid = current_element.Centroid();
current_centroid.lat = 100000*lat2y(current_centroid.lat/100000.);
uint64_t current_hilbert_value = HilbertCode::GetHilbertNumberForCoordinate(current_centroid);
input_wrapper_vector[element_counter].m_hilbert_value = current_hilbert_value;
}
//open leaf file
std::ofstream leaf_node_file(leaf_node_filename.c_str(), std::ios::binary);
leaf_node_file.write((char*) &m_element_count, sizeof(uint64_t));
//sort the hilbert-value representatives
std::sort(input_wrapper_vector.begin(), input_wrapper_vector.end());
std::vector<TreeNode> tree_nodes_in_level;
//pack M elements into leaf node and write to leaf file
uint64_t processed_objects_count = 0;
while(processed_objects_count < m_element_count) {
LeafNode current_leaf;
TreeNode current_node;
for(uint32_t current_element_index = 0; RTREE_LEAF_NODE_SIZE > current_element_index; ++current_element_index) {
if(m_element_count > (processed_objects_count + current_element_index)) {
uint32_t index_of_next_object = input_wrapper_vector[processed_objects_count + current_element_index].m_array_index;
current_leaf.objects[current_element_index] = input_data_vector[index_of_next_object];
++current_leaf.object_count;
}
}
//generate tree node that resemble the objects in leaf and store it for next level
current_node.minimum_bounding_rectangle.InitializeMBRectangle(current_leaf.objects, current_leaf.object_count);
current_node.child_is_on_disk = true;
current_node.children[0] = tree_nodes_in_level.size();
tree_nodes_in_level.push_back(current_node);
//write leaf_node to leaf node file
leaf_node_file.write((char*)&current_leaf, sizeof(current_leaf));
processed_objects_count += current_leaf.object_count;
}
//close leaf file
leaf_node_file.close();
uint32_t processing_level = 0;
while(1 < tree_nodes_in_level.size()) {
std::vector<TreeNode> tree_nodes_in_next_level;
uint32_t processed_tree_nodes_in_level = 0;
while(processed_tree_nodes_in_level < tree_nodes_in_level.size()) {
TreeNode parent_node;
//pack RTREE_BRANCHING_FACTOR elements into tree_nodes each
for(
uint32_t current_child_node_index = 0;
RTREE_BRANCHING_FACTOR > current_child_node_index;
++current_child_node_index
) {
if(processed_tree_nodes_in_level < tree_nodes_in_level.size()) {
TreeNode & current_child_node = tree_nodes_in_level[processed_tree_nodes_in_level];
//add tree node to parent entry
parent_node.children[current_child_node_index] = m_search_tree.size();
m_search_tree.push_back(current_child_node);
//augment MBR of parent
parent_node.minimum_bounding_rectangle.AugmentMBRectangle(current_child_node.minimum_bounding_rectangle);
//increase counters
++parent_node.child_count;
++processed_tree_nodes_in_level;
}
}
tree_nodes_in_next_level.push_back(parent_node);
}
tree_nodes_in_level.swap(tree_nodes_in_next_level);
++processing_level;
}
BOOST_ASSERT_MSG(1 == tree_nodes_in_level.size(), "tree broken, more than one root node");
//last remaining entry is the root node, store it
m_search_tree.push_back(tree_nodes_in_level[0]);
//reverse and renumber tree to have root at index 0
std::reverse(m_search_tree.begin(), m_search_tree.end());
#pragma omp parallel for schedule(guided)
for(uint32_t i = 0; i < m_search_tree.size(); ++i) {
TreeNode & current_tree_node = m_search_tree[i];
for(uint32_t j = 0; j < current_tree_node.child_count; ++j) {
const uint32_t old_id = current_tree_node.children[j];
const uint32_t new_id = m_search_tree.size() - old_id - 1;
current_tree_node.children[j] = new_id;
}
}
//open tree file
std::ofstream tree_node_file(tree_node_filename.c_str(), std::ios::binary);
uint32_t size_of_tree = m_search_tree.size();
BOOST_ASSERT_MSG(0 < size_of_tree, "tree empty");
tree_node_file.write((char *)&size_of_tree, sizeof(uint32_t));
tree_node_file.write((char *)&m_search_tree[0], sizeof(TreeNode)*size_of_tree);
//close tree node file.
tree_node_file.close();
double time2 = get_timestamp();
INFO("finished r-tree construction in " << (time2-time1) << " seconds");
}
//Read-only operation for queries
explicit StaticRTree(
const std::string & node_filename,
const std::string & leaf_filename
) : m_leaf_node_filename(leaf_filename) {
//open tree node file and load into RAM.
std::ifstream tree_node_file(node_filename.c_str(), std::ios::binary);
uint32_t tree_size = 0;
tree_node_file.read((char*)&tree_size, sizeof(uint32_t));
//INFO("reading " << tree_size << " tree nodes in " << (sizeof(TreeNode)*tree_size) << " bytes");
m_search_tree.resize(tree_size);
tree_node_file.read((char*)&m_search_tree[0], sizeof(TreeNode)*tree_size);
tree_node_file.close();
//open leaf node file and store thread specific pointer
std::ifstream leaf_node_file(leaf_filename.c_str(), std::ios::binary);
leaf_node_file.read((char*)&m_element_count, sizeof(uint64_t));
leaf_node_file.close();
//INFO( tree_size << " nodes in search tree");
//INFO( m_element_count << " elements in leafs");
}
/*
inline void FindKNearestPhantomNodesForCoordinate(
const _Coordinate & location,
const unsigned zoom_level,
const unsigned candidate_count,
std::vector<std::pair<PhantomNode, double> > & result_vector
) const {
bool ignore_tiny_components = (zoom_level <= 14);
DataT nearest_edge;
uint32_t io_count = 0;
uint32_t explored_tree_nodes_count = 0;
INFO("searching for coordinate " << input_coordinate);
double min_dist = DBL_MAX;
double min_max_dist = DBL_MAX;
bool found_a_nearest_edge = false;
_Coordinate nearest, current_start_coordinate, current_end_coordinate;
//initialize queue with root element
std::priority_queue<QueryCandidate> traversal_queue;
traversal_queue.push(QueryCandidate(0, m_search_tree[0].minimum_bounding_rectangle.GetMinDist(input_coordinate)));
BOOST_ASSERT_MSG(FLT_EPSILON > (0. - traversal_queue.top().min_dist), "Root element in NN Search has min dist != 0.");
while(!traversal_queue.empty()) {
const QueryCandidate current_query_node = traversal_queue.top(); traversal_queue.pop();
++explored_tree_nodes_count;
bool prune_downward = (current_query_node.min_dist >= min_max_dist);
bool prune_upward = (current_query_node.min_dist >= min_dist);
if( !prune_downward && !prune_upward ) { //downward pruning
TreeNode & current_tree_node = m_search_tree[current_query_node.node_id];
if (current_tree_node.child_is_on_disk) {
LeafNode current_leaf_node;
LoadLeafFromDisk(current_tree_node.children[0], current_leaf_node);
++io_count;
for(uint32_t i = 0; i < current_leaf_node.object_count; ++i) {
DataT & current_edge = current_leaf_node.objects[i];
if(ignore_tiny_components && current_edge.belongsToTinyComponent) {
continue;
}
double current_ratio = 0.;
double current_perpendicular_distance = ComputePerpendicularDistance(
input_coordinate,
_Coordinate(current_edge.lat1, current_edge.lon1),
_Coordinate(current_edge.lat2, current_edge.lon2),
nearest,
&current_ratio
);
if(
current_perpendicular_distance < min_dist
&& !DoubleEpsilonCompare(
current_perpendicular_distance,
min_dist
)
) { //found a new minimum
min_dist = current_perpendicular_distance;
result_phantom_node.edgeBasedNode = current_edge.id;
result_phantom_node.nodeBasedEdgeNameID = current_edge.nameID;
result_phantom_node.weight1 = current_edge.weight;
result_phantom_node.weight2 = INT_MAX;
result_phantom_node.location = nearest;
current_start_coordinate.lat = current_edge.lat1;
current_start_coordinate.lon = current_edge.lon1;
current_end_coordinate.lat = current_edge.lat2;
current_end_coordinate.lon = current_edge.lon2;
nearest_edge = current_edge;
found_a_nearest_edge = true;
} else if(
DoubleEpsilonCompare(current_perpendicular_distance, min_dist) &&
1 == abs(current_edge.id - result_phantom_node.edgeBasedNode )
&& CoordinatesAreEquivalent(
current_start_coordinate,
_Coordinate(
current_edge.lat1,
current_edge.lon1
),
_Coordinate(
current_edge.lat2,
current_edge.lon2
),
current_end_coordinate
)
) {
result_phantom_node.edgeBasedNode = std::min(current_edge.id, result_phantom_node.edgeBasedNode);
result_phantom_node.weight2 = current_edge.weight;
}
}
} else {
//traverse children, prune if global mindist is smaller than local one
for (uint32_t i = 0; i < current_tree_node.child_count; ++i) {
const int32_t child_id = current_tree_node.children[i];
TreeNode & child_tree_node = m_search_tree[child_id];
RectangleT & child_rectangle = child_tree_node.minimum_bounding_rectangle;
const double current_min_dist = child_rectangle.GetMinDist(input_coordinate);
const double current_min_max_dist = child_rectangle.GetMinMaxDist(input_coordinate);
if( current_min_max_dist < min_max_dist ) {
min_max_dist = current_min_max_dist;
}
if (current_min_dist > min_max_dist) {
continue;
}
if (current_min_dist > min_dist) { //upward pruning
continue;
}
traversal_queue.push(QueryCandidate(child_id, current_min_dist));
}
}
}
}
const double distance_to_edge =
ApproximateDistance (
_Coordinate(nearest_edge.lat1, nearest_edge.lon1),
result_phantom_node.location
);
const double length_of_edge =
ApproximateDistance(
_Coordinate(nearest_edge.lat1, nearest_edge.lon1),
_Coordinate(nearest_edge.lat2, nearest_edge.lon2)
);
const double ratio = (found_a_nearest_edge ?
std::min(1., distance_to_edge/ length_of_edge ) : 0 );
result_phantom_node.weight1 *= ratio;
if(INT_MAX != result_phantom_node.weight2) {
result_phantom_node.weight2 *= (1.-ratio);
}
result_phantom_node.ratio = ratio;
//Hack to fix rounding errors and wandering via nodes.
if(std::abs(input_coordinate.lon - result_phantom_node.location.lon) == 1) {
result_phantom_node.location.lon = input_coordinate.lon;
}
if(std::abs(input_coordinate.lat - result_phantom_node.location.lat) == 1) {
result_phantom_node.location.lat = input_coordinate.lat;
}
INFO("mindist: " << min_distphantom_node.isBidirected() ? "yes" : "no") );
return found_a_nearest_edge;
}
*/
bool FindPhantomNodeForCoordinate(
const _Coordinate & input_coordinate,
PhantomNode & result_phantom_node,
const unsigned zoom_level
) {
bool ignore_tiny_components = (zoom_level <= 14);
DataT nearest_edge;
uint32_t io_count = 0;
uint32_t explored_tree_nodes_count = 0;
//INFO("searching for coordinate " << input_coordinate);
double min_dist = DBL_MAX;
double min_max_dist = DBL_MAX;
bool found_a_nearest_edge = false;
_Coordinate nearest, current_start_coordinate, current_end_coordinate;
//initialize queue with root element
std::priority_queue<QueryCandidate> traversal_queue;
double current_min_dist = m_search_tree[0].minimum_bounding_rectangle.GetMinDist(input_coordinate);
traversal_queue.push(
QueryCandidate(0, current_min_dist)
);
BOOST_ASSERT_MSG(
FLT_EPSILON > (0. - traversal_queue.top().min_dist),
"Root element in NN Search has min dist != 0."
);
while(!traversal_queue.empty()) {
const QueryCandidate current_query_node = traversal_queue.top(); traversal_queue.pop();
++explored_tree_nodes_count;
bool prune_downward = (current_query_node.min_dist >= min_max_dist);
bool prune_upward = (current_query_node.min_dist >= min_dist);
if( !prune_downward && !prune_upward ) { //downward pruning
TreeNode & current_tree_node = m_search_tree[current_query_node.node_id];
if (current_tree_node.child_is_on_disk) {
LeafNode current_leaf_node;
LoadLeafFromDisk(current_tree_node.children[0], current_leaf_node);
++io_count;
//INFO("checking " << current_leaf_node.object_count << " elements");
for(uint32_t i = 0; i < current_leaf_node.object_count; ++i) {
DataT & current_edge = current_leaf_node.objects[i];
if(ignore_tiny_components && current_edge.belongsToTinyComponent) {
continue;
}
if(current_edge.isIgnored()) {
continue;
}
double current_ratio = 0.;
double current_perpendicular_distance = ComputePerpendicularDistance(
input_coordinate,
_Coordinate(current_edge.lat1, current_edge.lon1),
_Coordinate(current_edge.lat2, current_edge.lon2),
nearest,
&current_ratio
);
if(
current_perpendicular_distance < min_dist
&& !DoubleEpsilonCompare(
current_perpendicular_distance,
min_dist
)
) { //found a new minimum
min_dist = current_perpendicular_distance;
result_phantom_node.edgeBasedNode = current_edge.id;
result_phantom_node.nodeBasedEdgeNameID = current_edge.nameID;
result_phantom_node.weight1 = current_edge.weight;
result_phantom_node.weight2 = INT_MAX;
result_phantom_node.location = nearest;
current_start_coordinate.lat = current_edge.lat1;
current_start_coordinate.lon = current_edge.lon1;
current_end_coordinate.lat = current_edge.lat2;
current_end_coordinate.lon = current_edge.lon2;
nearest_edge = current_edge;
found_a_nearest_edge = true;
} else if(
DoubleEpsilonCompare(current_perpendicular_distance, min_dist) &&
1 == abs(current_edge.id - result_phantom_node.edgeBasedNode )
&& CoordinatesAreEquivalent(
current_start_coordinate,
_Coordinate(
current_edge.lat1,
current_edge.lon1
),
_Coordinate(
current_edge.lat2,
current_edge.lon2
),
current_end_coordinate
)
) {
BOOST_ASSERT_MSG(current_edge.id != result_phantom_node.edgeBasedNode, "IDs not different");
//INFO("found bidirected edge on nodes " << current_edge.id << " and " << result_phantom_node.edgeBasedNode);
result_phantom_node.weight2 = current_edge.weight;
if(current_edge.id < result_phantom_node.edgeBasedNode) {
result_phantom_node.edgeBasedNode = current_edge.id;
std::swap(result_phantom_node.weight1, result_phantom_node.weight2);
std::swap(current_end_coordinate, current_start_coordinate);
// INFO("case 2");
}
//INFO("w1: " << result_phantom_node.weight1 << ", w2: " << result_phantom_node.weight2);
}
}
} else {
//traverse children, prune if global mindist is smaller than local one
for (uint32_t i = 0; i < current_tree_node.child_count; ++i) {
const int32_t child_id = current_tree_node.children[i];
TreeNode & child_tree_node = m_search_tree[child_id];
RectangleT & child_rectangle = child_tree_node.minimum_bounding_rectangle;
const double current_min_dist = child_rectangle.GetMinDist(input_coordinate);
const double current_min_max_dist = child_rectangle.GetMinMaxDist(input_coordinate);
if( current_min_max_dist < min_max_dist ) {
min_max_dist = current_min_max_dist;
}
if (current_min_dist > min_max_dist) {
continue;
}
if (current_min_dist > min_dist) { //upward pruning
continue;
}
traversal_queue.push(QueryCandidate(child_id, current_min_dist));
}
}
}
}
const double ratio = (found_a_nearest_edge ?
std::min(1., ApproximateDistance(current_start_coordinate,
result_phantom_node.location)/ApproximateDistance(current_start_coordinate, current_end_coordinate)
) : 0
);
result_phantom_node.weight1 *= ratio;
if(INT_MAX != result_phantom_node.weight2) {
result_phantom_node.weight2 *= (1.-ratio);
}
result_phantom_node.ratio = ratio;
//Hack to fix rounding errors and wandering via nodes.
if(std::abs(input_coordinate.lon - result_phantom_node.location.lon) == 1) {
result_phantom_node.location.lon = input_coordinate.lon;
}
if(std::abs(input_coordinate.lat - result_phantom_node.location.lat) == 1) {
result_phantom_node.location.lat = input_coordinate.lat;
}
return found_a_nearest_edge;
}
private:
inline void LoadLeafFromDisk(const uint32_t leaf_id, LeafNode& result_node) {
if(!thread_local_rtree_stream.get() || !thread_local_rtree_stream->is_open()) {
thread_local_rtree_stream.reset(
new std::ifstream(
m_leaf_node_filename.c_str(),
std::ios::in | std::ios::binary
)
);
}
if(!thread_local_rtree_stream->good()) {
thread_local_rtree_stream->clear(std::ios::goodbit);
DEBUG("Resetting stale filestream");
}
uint64_t seek_pos = sizeof(uint64_t) + leaf_id*sizeof(LeafNode);
thread_local_rtree_stream->seekg(seek_pos);
thread_local_rtree_stream->read((char *)&result_node, sizeof(LeafNode));
}
inline double ComputePerpendicularDistance(
const _Coordinate& inputPoint,
const _Coordinate& source,
const _Coordinate& target,
_Coordinate& nearest, double *r) const {
const double x = static_cast<double>(inputPoint.lat);
const double y = static_cast<double>(inputPoint.lon);
const double a = static_cast<double>(source.lat);
const double b = static_cast<double>(source.lon);
const double c = static_cast<double>(target.lat);
const double d = static_cast<double>(target.lon);
double p,q,mX,nY;
if(fabs(a-c) > FLT_EPSILON){
const double m = (d-b)/(c-a); // slope
// Projection of (x,y) on line joining (a,b) and (c,d)
p = ((x + (m*y)) + (m*m*a - m*b))/(1. + m*m);
q = b + m*(p - a);
} else {
p = c;
q = y;
}
nY = (d*p - c*q)/(a*d - b*c);
mX = (p - nY*a)/c;// These values are actually n/m+n and m/m+n , we need
// not calculate the explicit values of m an n as we
// are just interested in the ratio
if(std::isnan(mX)) {
*r = (target == inputPoint) ? 1. : 0.;
} else {
*r = mX;
}
if(*r<=0.){
nearest.lat = source.lat;
nearest.lon = source.lon;
return ((b - y)*(b - y) + (a - x)*(a - x));
// return std::sqrt(((b - y)*(b - y) + (a - x)*(a - x)));
} else if(*r >= 1.){
nearest.lat = target.lat;
nearest.lon = target.lon;
return ((d - y)*(d - y) + (c - x)*(c - x));
// return std::sqrt(((d - y)*(d - y) + (c - x)*(c - x)));
}
// point lies in between
nearest.lat = p;
nearest.lon = q;
// return std::sqrt((p-x)*(p-x) + (q-y)*(q-y));
return (p-x)*(p-x) + (q-y)*(q-y);
}
inline bool CoordinatesAreEquivalent(const _Coordinate & a, const _Coordinate & b, const _Coordinate & c, const _Coordinate & d) const {
return (a == b && c == d) || (a == c && b == d) || (a == d && b == c);
}
inline bool DoubleEpsilonCompare(const double d1, const double d2) const {
return (std::fabs(d1 - d2) < FLT_EPSILON);
}
};
//[1] "On Packing R-Trees"; I. Kamel, C. Faloutsos; 1993; DOI: 10.1145/170088.170403
//[2] "Nearest Neighbor Queries", N. Roussopulos et al; 1995; DOI: 10.1145/223784.223794
#endif /* STATICRTREE_H_ */
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