utils.h

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// ----------------------------------------------------------------------------
// -                        CloudViewer: www.cloudViewer.org                  -
// ----------------------------------------------------------------------------
// Copyright (c) 2018-2024 www.cloudViewer.org
// SPDX-License-Identifier: MIT
// ----------------------------------------------------------------------------
 
#pragma once
 
#include "feature/types.h"
 
namespace colmap {
 
// Convert feature keypoints to vector of points.
std::vector<Eigen::Vector2d> FeatureKeypointsToPointsVector(
        const FeatureKeypoints& keypoints);
 
// L2-normalize feature descriptor, where each row represents one feature.
Eigen::MatrixXf L2NormalizeFeatureDescriptors(
        const Eigen::MatrixXf& descriptors);
 
// L1-Root-normalize feature descriptors, where each row represents one feature.
// See "Three things everyone should know to improve object retrieval",
// Relja Arandjelovic and Andrew Zisserman, CVPR 2012.
Eigen::MatrixXf L1RootNormalizeFeatureDescriptors(
        const Eigen::MatrixXf& descriptors);
 
// Convert normalized floating point feature descriptor to unsigned byte
// representation by linear scaling from range [0, 0.5] to [0, 255]. Truncation
// to a maximum value of 0.5 is used to avoid precision loss and follows the
// common practice of representing SIFT vectors.
FeatureDescriptors FeatureDescriptorsToUnsignedByte(
        const Eigen::MatrixXf& descriptors);
 
// Extract the descriptors corresponding to the largest-scale features.
void ExtractTopScaleFeatures(FeatureKeypoints* keypoints,
                             FeatureDescriptors* descriptors,
                             const size_t num_features);
 
}  // namespace colmap