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// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// * Neither the name of ETH Zurich and UNC Chapel Hill nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// Author: Johannes L. Schoenberger (jsch-at-demuc-dot-de)
#ifndef COLMAP_SRC_BASE_SCENE_CLUSTERING_H_
#define COLMAP_SRC_BASE_SCENE_CLUSTERING_H_
#include <list>
#include <vector>
#include "base/database.h"
#include "util/types.h"
namespace colmap {
// Scene clustering approach using normalized cuts on the scene graph. The scene
// is hierarchically partitioned into overlapping clusters until a maximum
// number of images is in a leaf node.
class SceneClustering {
public:
struct Options {
// Flag for hierarchical vs flat clustering
bool is_hierarchical = true;
// The branching factor of the hierarchical clustering.
int branching = 2;
// The number of overlapping images between child clusters.
int image_overlap = 50;
// The max related images matches to look for in a flat cluster
int num_image_matches = 20;
// The maximum number of images in a leaf node cluster, otherwise the
// cluster is further partitioned using the given branching factor. Note
// that a cluster leaf node will have at most `leaf_max_num_images +
// overlap` images to satisfy the overlap constraint.
int leaf_max_num_images = 500;
bool Check() const;
};
struct Cluster {
std::vector<image_t> image_ids;
std::vector<Cluster> child_clusters;
};
SceneClustering(const Options& options);
void Partition(const std::vector<std::pair<image_t, image_t>>& image_pairs,
const std::vector<int>& num_inliers);
const Cluster* GetRootCluster() const;
std::vector<const Cluster*> GetLeafClusters() const;
static SceneClustering Create(const Options& options,
const Database& database);
private:
void PartitionHierarchicalCluster(
const std::vector<std::pair<int, int>>& edges,
const std::vector<int>& weights, Cluster* cluster);
void PartitionFlatCluster(const std::vector<std::pair<int, int>>& edges,
const std::vector<int>& weights);
const Options options_;
std::unique_ptr<Cluster> root_cluster_;
};
} // namespace colmap
#endif // COLMAP_SRC_BASE_SCENE_CLUSTERING_H_
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