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added vertexweighted sampling

This commit is contained in:
Paolo Cignoni 2008-06-04 13:29:04 +00:00
parent 7f4d6cbd76
commit a29f21fa59
1 changed files with 79 additions and 8 deletions
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87
vcg/complex/trimesh/point_sampling.h
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@ -62,6 +62,84 @@ void AllVertex(MetroMesh & m, VertexSampler &ps)
ps.AddVert(*vi);
}
}
/// Sample the vertices in a weighted way. Each vertex has a probabiltiy of being chosen
/// that is proportional to its quality.
/// It assumes that you are asking a number of vertices smaller than nv;
/// Algorithm:
/// 1) normalize quality so that sum q == 1;
/// 2) shuffle vertices.
/// 3) for each vertices choose it if rand > thr;
static void VertexWeighted(MetroMesh & m, VertexSampler &ps, int sampleNum)
{
ScalarType qSum = 0;
VertexIterator vi;
for(vi = m.vert.begin(); vi != m.vert.end(); ++vi)
if(!(*vi).IsD())
qSum += (*vi).Q();
ScalarType samplePerUnit = sampleNum/qSum;
ScalarType floatSampleNum =0;
std::vector<VertexPointer> vertVec;
FillAndShuffleVertexPointVector(m,vertVec);
std::vector<bool> vertUsed(m.vn,false);
int i=0; int cnt=0;
while(cnt < sampleNum)
{
if(vertUsed[i])
{
floatSampleNum += vertVec[i]->Q() * samplePerUnit;
int vertSampleNum = (int) floatSampleNum;
floatSampleNum -= (float) vertSampleNum;
// for every sample p_i in T...
if(vertSampleNum > 1)
{
ps.AddVert(*vertVec[i]);
cnt++;
vertUsed[i]=true;
}
}
i = (i+1)%m.vn;
}
}
/// Sample the vertices in a uniform way. Each vertex has a probabiltiy of being chosen
/// that is proportional to the area it represent.
static void VertexAreaUniform(MetroMesh & m, VertexSampler &ps, int sampleNum)
{
VertexIterator vi;
for(vi = m.vert.begin(); vi != m.vert.end(); ++vi)
if(!(*vi).IsD())
(*vi).Q() = 0;
FaceIterator fi;
for(fi = m.face.begin(); fi != m.face.end(); ++fi)
if(!(*fi).IsD())
{
ScalarType areaThird = DoubleArea(*fi)/6.0;
(*fi).V(0).Q()+=areaThird;
(*fi).V(1).Q()+=areaThird;
(*fi).V(2).Q()+=areaThird;
}
VertexWeighted(m,ps,sampleNum);
}
static void FillAndShuffleVertexPointVector(MetroMesh & m, std::vector<VertexPointer> vertVec)
{
VertexIterator vi;
for(vi=m.vert.begin();vi!=m.vert.end();++vi)
if(!(*vi).IsD()) vertVec.push_back(&*vi);
assert(vertVec.size()=m.vn);
std::random_shuffle(vertVec.begin(),vertVec.end());
}
/// Sample the vertices in a uniform way. Each vertex has the same probabiltiy of being chosen.
static void VertexUniform(MetroMesh & m, VertexSampler &ps, int sampleNum)
{
if(sampleNum>=m.vn)
@ -71,14 +149,7 @@ static void VertexUniform(MetroMesh & m, VertexSampler &ps, int sampleNum)
}
std::vector<VertexPointer> vertVec;
VertexIterator vi;
for(vi=m.vert.begin();vi!=m.vert.end();++vi)
if(!(*vi).IsD()) vertVec.push_back(&*vi);
assert(vertVec.size()=m.vn);
std::random_shuffle(vertVec.begin(),vertVec.end());
FillAndShuffleVertexPointVector(m,vertVec);
for(int i =0; i< sampleNum; ++i)
ps.AddVert(*vertVec[i]);