Open-Harbor/osrm-backend
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases 3 Wiki Activity

use integer approximation for polyline generalization

Browse Source
This commit is contained in:
Dennis Luxen 2014-05-30 14:34:04 +02:00
parent 21eb5b661d
commit f3ad14cb7f
2 changed files with 28 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
Algorithms/DouglasPeucker.cpp
View File

@ -38,25 +38,25 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <limits> #include <limits>
DouglasPeucker::DouglasPeucker() DouglasPeucker::DouglasPeucker()
: douglas_peucker_thresholds({262144.f, // z0 : douglas_peucker_thresholds({2621440, // z0
131072.f, // z1 1310720, // z1
65536.f, // z2 655360, // z2
32768.f, // z3 327680, // z3
16384.f, // z4 163840, // z4
8192.f, // z5 81920, // z5
4096.f, // z6 40960, // z6
2048.f, // z7 20480, // z7
960.f, // z8 9600, // z8
480.f, // z9 4800, // z9
240.f, // z10 2800, // z10
90.f, // z11 900, // z11
50.f, // z12 600, // z12
25.f, // z13 275, // z13
15.f, // z14 160, // z14
5.f, // z15 60, // z15
.65f, // z16 8, // z16
.5f, // z17 6, // z17
.35f // z18 4 // z18
}) })
{ {
} }
@ -79,16 +79,10 @@ void DouglasPeucker::Run(std::vector<SegmentInformation> &input_geometry, const
// Sweep over array and identify those ranges that need to be checked // Sweep over array and identify those ranges that need to be checked
do do
{ {
if (!input_geometry[left_border].necessary)
{
SimpleLogger().Write() << "broken interval [" << left_border << "," << right_border << "]";
}
BOOST_ASSERT_MSG(input_geometry[left_border].necessary,
"left border must be necessary");
BOOST_ASSERT_MSG(input_geometry.back().necessary, "right border must be necessary");
if (input_geometry[right_border].necessary) if (input_geometry[right_border].necessary)
{ {
BOOST_ASSERT(input_geometry[left_border].necessary);
BOOST_ASSERT(input_geometry[right_border].necessary);
recursion_stack.emplace(left_border, right_border); recursion_stack.emplace(left_border, right_border);
left_border = right_border; left_border = right_border;
} }
@ -104,24 +98,24 @@ void DouglasPeucker::Run(std::vector<SegmentInformation> &input_geometry, const
BOOST_ASSERT_MSG(input_geometry[pair.second].necessary, "right border must be necessary"); BOOST_ASSERT_MSG(input_geometry[pair.second].necessary, "right border must be necessary");
BOOST_ASSERT_MSG(pair.second < input_geometry.size(), "right border outside of geometry"); BOOST_ASSERT_MSG(pair.second < input_geometry.size(), "right border outside of geometry");
BOOST_ASSERT_MSG(pair.first < pair.second, "left border on the wrong side"); BOOST_ASSERT_MSG(pair.first < pair.second, "left border on the wrong side");
float max_distance = std::numeric_limits<float>::min(); int max_int_distance = 0;
unsigned farthest_element_index = pair.second; unsigned farthest_element_index = pair.second;
// find index idx of element with max_distance // find index idx of element with max_distance
for (unsigned i = pair.first + 1; i < pair.second; ++i) for (unsigned i = pair.first + 1; i < pair.second; ++i)
{ {
const float temp_dist = FixedPointCoordinate::ComputePerpendicularDistance( const int int_dist = FixedPointCoordinate::OrderedPerpendicularDistanceApproximation(
input_geometry[i].location, input_geometry[i].location,
input_geometry[pair.first].location, input_geometry[pair.first].location,
input_geometry[pair.second].location); input_geometry[pair.second].location);
const float distance = std::abs(temp_dist);
if (distance > douglas_peucker_thresholds[zoom_level] && distance > max_distance) if (int_dist > max_int_distance && int_dist > douglas_peucker_thresholds[zoom_level])
{ {
farthest_element_index = i; farthest_element_index = i;
max_distance = distance; max_int_distance = int_dist;
} }
} }
if (max_distance > douglas_peucker_thresholds[zoom_level]) if (max_int_distance > douglas_peucker_thresholds[zoom_level])
{ {
// mark idx as necessary // mark idx as necessary
input_geometry[farthest_element_index].necessary = true; input_geometry[farthest_element_index].necessary = true;

2
Algorithms/DouglasPeucker.h
View File

@ -44,7 +44,7 @@ struct SegmentInformation;
class DouglasPeucker class DouglasPeucker
{ {
private: private:
std::vector<float> douglas_peucker_thresholds; std::vector<int> douglas_peucker_thresholds;
typedef std::pair<unsigned, unsigned> GeometryRange; typedef std::pair<unsigned, unsigned> GeometryRange;
// Stack to simulate the recursion // Stack to simulate the recursion