songsenand
/
cgal
mirror of https://github.com/CGAL/cgal
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

random pick non-seed facets 

without proxies clear which invalidates existing proxy map
This commit is contained in:
Lingjie Zhu 2017-12-10 20:04:58 +08:00
parent a693b2d928
commit d7f7369416
1 changed files with 37 additions and 44 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

81
Surface_mesh_approximation/include/CGAL/vsa_approximation.h
View File

@ -1036,15 +1036,13 @@ private:
*/
std::size_t init_random(const std::size_t max_nb_proxies,
const std::size_t num_iterations) {
// random shuffled facets except for the bootstrapped connected component seed facets
std::vector<face_descriptor> shuffled_facets;
random_shuffle_non_seed_facets(shuffled_facets);
// reach to the number of proxies
for (std::size_t i = 0; i < shuffled_facets.size()
&& m_proxies.size() < max_nb_proxies; ++i)
m_proxies.push_back(fit_proxy_from_seed_facet(shuffled_facets[i], m_proxies.size()));
run(num_iterations);
// pick from current non seed facets randomly
std::vector<face_descriptor> picked_seeds;
if (random_pick_non_seed_facets(max_nb_proxies - m_proxies.size(), picked_seeds)) {
BOOST_FOREACH(face_descriptor f, picked_seeds)
m_proxies.push_back(fit_proxy_from_seed_facet(f, m_proxies.size()));
run(num_iterations);
}
return m_proxies.size();
}
@ -1103,33 +1101,22 @@ private:
std::size_t init_random_error(const std::size_t max_nb_proxies,
const FT min_error_drop,
const std::size_t num_iterations) {
// random shuffled facets except for the bootstrapped connected component seed facets
std::vector<face_descriptor> shuffled_facets;
random_shuffle_non_seed_facets(shuffled_facets);
// keep a copy of the connected components seeds
std::vector<face_descriptor> cc_seed_facets;
BOOST_FOREACH(const Proxy_wrapper &pxw, m_proxies)
cc_seed_facets.push_back(pxw.seed);
const FT initial_err = compute_total_error();
FT error_drop = min_error_drop * FT(2.0);
while (m_proxies.size() < max_nb_proxies && error_drop > min_error_drop) {
// try to double current number of proxies each time
std::size_t target_px = m_proxies.size();
if (target_px * 2 > max_nb_proxies)
target_px = max_nb_proxies;
else
target_px *= 2;
const std::size_t nb_px = m_proxies.size();
const std::size_t nb_to_add =
(nb_px * 2 > max_nb_proxies) ? max_nb_proxies - nb_px : nb_px;
// reset proxies to the bootstrapped connected components
m_proxies.clear();
BOOST_FOREACH(face_descriptor f, cc_seed_facets)
// pick from current non seed facets randomly
std::vector<face_descriptor> picked_seeds;
if (!random_pick_non_seed_facets(nb_to_add, picked_seeds))
return m_proxies.size();
BOOST_FOREACH(face_descriptor f, picked_seeds)
m_proxies.push_back(fit_proxy_from_seed_facet(f, m_proxies.size()));
for (std::size_t i = 0; i < shuffled_facets.size()
&& m_proxies.size() < target_px; ++i)
m_proxies.push_back(fit_proxy_from_seed_facet(shuffled_facets[i], m_proxies.size()));
run(num_iterations);
const FT err = compute_total_error();
@ -1347,36 +1334,42 @@ private:
}
/*!
* @brief Random shuffle the non-seed facets into an empty vector,
* to prepare for consecutive random seed facets selection (no interleaved re-fitting).
* @brief Pick a number of non-seed facets into an empty vector randomly.
* @param nb_requested requested number of facets
* @param[out] facets shuffled facets vector
* @return true if requested number of facets are selected, false otherwise
*/
void random_shuffle_non_seed_facets(std::vector<face_descriptor> &facets) {
bool random_pick_non_seed_facets(const std::size_t nb_requested,
std::vector<face_descriptor> &facets) {
if (nb_requested + m_proxies.size() >= num_faces(*m_ptm))
return false;
std::set<face_descriptor> seed_facets_set;
BOOST_FOREACH(const Proxy_wrapper &pxw, m_proxies)
seed_facets_set.insert(pxw.seed);
if (num_faces(*m_ptm) <= m_proxies.size())
return;
const std::size_t nbf = num_faces(*m_ptm) - m_proxies.size();
facets.reserve(nbf);
const std::size_t nb_nsf = num_faces(*m_ptm) - m_proxies.size();
std::vector<face_descriptor> non_seed_facets;
non_seed_facets.reserve(nb_nsf);
BOOST_FOREACH(face_descriptor f, faces(*m_ptm)) {
if (seed_facets_set.find(f) != seed_facets_set.end())
continue;
facets.push_back(f);
non_seed_facets.push_back(f);
}
// random shuffle
for (std::size_t i = 0; i < nbf; ++i) {
// random shuffle first few facets
for (std::size_t i = 0; i < nb_requested; ++i) {
// swap ith element with a random one
std::size_t r = static_cast<std::size_t>(
static_cast<double>(std::rand()) / static_cast<double>(RAND_MAX) *
static_cast<double>(nbf - 1));
face_descriptor tmp = facets[r];
facets[r] = facets[i];
facets[i] = tmp;
static_cast<double>(nb_nsf - 1));
std::swap(non_seed_facets[i], non_seed_facets[r]);
}
for (std::size_t i = 0; i < nb_requested; ++i)
facets.push_back(non_seed_facets[i]);
return true;
}
/*!