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Updated line generalization thresholds

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This commit is contained in:
DennisOSRM 2012-10-08 16:25:59 +02:00
parent 8794db633b
commit 38ba10ddad
1 changed files with 8 additions and 6 deletions
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14
Algorithms/DouglasPeucker.h
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@ -22,6 +22,7 @@ or see http://www.gnu.org/licenses/agpl.txt.
#define DOUGLASPEUCKER_H_ #define DOUGLASPEUCKER_H_
#include <cassert> #include <cassert>
#include <cmath>
#include <cfloat> #include <cfloat>
#include <stack> #include <stack>
@ -35,7 +36,8 @@ or see http://www.gnu.org/licenses/agpl.txt.
* Note: points may also be pre-selected*/ * Note: points may also be pre-selected*/
//These thresholds are more or less heuristically chosen. //These thresholds are more or less heuristically chosen.
static double DouglasPeuckerThresholds[19] = { 10240000., 5120000., 2560000., 1280000., 640000., 320000., 160000., 80000., 40000., 20000., 10000., 5000., 2400., 1200., 200, 16, 6, 3., 1. }; // 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
static double DouglasPeuckerThresholds[19] = { 32000000., 16240000., 80240000., 40240000., 20000000., 10000000., 500000., 240000., 120000., 60000., 30000., 19000., 5000., 2000., 200, 16, 6, 3. , 3. };
template<class PointT> template<class PointT>
class DouglasPeucker { class DouglasPeucker {
@ -45,7 +47,7 @@ private:
std::stack<PairOfPoints > recursionStack; std::stack<PairOfPoints > recursionStack;
double ComputeDistanceOfPointToLine(const _Coordinate& inputPoint, const _Coordinate& source, const _Coordinate& target) const { double ComputeDistanceOfPointToLine(const _Coordinate& inputPoint, const _Coordinate& source, const _Coordinate& target) const {
double r; double r = 0.;
const double x = static_cast<double>(inputPoint.lat); const double x = static_cast<double>(inputPoint.lat);
const double y = static_cast<double>(inputPoint.lon); const double y = static_cast<double>(inputPoint.lon);
const double a = static_cast<double>(source.lat); const double a = static_cast<double>(source.lat);
@ -64,11 +66,11 @@ private:
} }
nY = (d*p - c*q)/(a*d - b*c); 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 neednot calculate the values of m an n as we are just interested in the ratio mX = (p - nY*a)/c;// These values are actually n/m+n and m/m+n , we neednot calculate the values of m an n as we are just interested in the ratio
r = mX; r = std::isnan(mX) ? 0. : mX;
if(r<=0){ if(r<=0.){
return ((b - y)*(b - y) + (a - x)*(a - x)); return ((b - y)*(b - y) + (a - x)*(a - x));
} }
else if(r >= 1){ else if(r >= 1.){
return ((d - y)*(d - y) + (c - x)*(c - x)); return ((d - y)*(d - y) + (c - x)*(c - x));
} }
@ -108,7 +110,7 @@ public:
std::size_t indexOfFarthestElement = pair.second; std::size_t indexOfFarthestElement = pair.second;
//find index idx of element with maxDistance //find index idx of element with maxDistance
for(std::size_t i = pair.first+1; i < pair.second; ++i){ for(std::size_t i = pair.first+1; i < pair.second; ++i){
double distance = std::fabs(ComputeDistanceOfPointToLine(inputVector[i].location, inputVector[pair.first].location, inputVector[pair.second].location)); const double distance = std::fabs(ComputeDistanceOfPointToLine(inputVector[i].location, inputVector[pair.first].location, inputVector[pair.second].location));
if(distance > DouglasPeuckerThresholds[zoomLevel] && distance > maxDistance) { if(distance > DouglasPeuckerThresholds[zoomLevel] && distance > maxDistance) {
indexOfFarthestElement = i; indexOfFarthestElement = i;
maxDistance = distance; maxDistance = distance;