SIFT_loader.cpp

/*===========================================================================*\
 *                                                                           *
 *                            ACG Localizer                                  *
 *      Copyright (C) 2011 by Computer Graphics Group, RWTH Aachen           *
 *                           www.rwth-graphics.de                            *
 *                                                                           *
 *---------------------------------------------------------------------------* 
 *  This file is part of ACG Localizer                                       *
 *                                                                           *
 *  ACG Localizer is free software: you can redistribute it and/or modify    *
 *  it under the terms of the GNU General Public License as published by     *
 *  the Free Software Foundation, either version 3 of the License, or        *
 *  (at your option) any later version.                                      *
 *                                                                           *
 *  ACG Localizer is distributed in the hope that it will be useful,         *
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of           *
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            *
 *  GNU General Public License for more details.                             *
 *                                                                           *
 *  You should have received a copy of the GNU General Public License        *
 *  along with ACG Localizer.  If not, see <http://www.gnu.org/licenses/>.   *
 *                                                                           *
 \*===========================================================================*/

#include "SIFT_loader.hpp"

#include <iostream>
#include <fstream>
#include <cmath>

SIFT_loader::SIFT_loader() {
	mNbFeatures = 0;
	mKeypoints.clear();
	mDescriptors.clear();
}

SIFT_loader::~SIFT_loader() {
	clear_data();
}

void SIFT_loader::load_features(const char *filename, SIFT_FORMAT format) {
	clear_data();
	bool loaded = load_Lowe_features(filename);

	if (!loaded)
		std::cerr << "Could not load the features from the given file "
				<< filename << std::endl;
}

bool SIFT_loader::save_features_lowe(const char *filename) {
	//now open the .sift file and read out the interest points
	// format:
	//
	// nb_keypoints size_descriptor (should be 128)
	// for each keypoint:
	//	y x scale orientation(radians)
	//    descripor( size_descriptor many unsigned char values) (6 lines with 20 values, 1 with 8 values)
	//the coordinates of the interest points are stored in a coordinate system in which the origin corresponds to the upper left of the image

	std::ofstream outstream(filename, std::ios::out);

	if (!outstream.is_open())
		return false;

	// save the number of keypoints and the size of the descriptors
	outstream << mNbFeatures << " 128" << std::endl;

	// load the keypoints and their descriptors
	for (uint32_t i = 0; i < mNbFeatures; ++i) {
		outstream << mKeypoints[i].y << " " << mKeypoints[i].x << " "
				<< mKeypoints[i].scale << " " << mKeypoints[i].orientation
				<< std::endl;

		outstream << (int) mDescriptors[i][0] << " ";
		for (int j = 1; j < 128; ++j) {
			if (j % 20 == 0)
				outstream << std::endl;
			outstream << (int) mDescriptors[i][j] << " ";
		}
		outstream << std::endl;
	}

	outstream.close();

	return true;
}

void SIFT_loader::clear_data() {
	for (uint32_t i = 0; i < mNbFeatures; ++i) {
		if (mDescriptors[i] != 0)
			delete[] mDescriptors[i];
		mDescriptors[i] = 0;
	}
	mKeypoints.clear();
	mDescriptors.clear();
}

uint32_t SIFT_loader::get_nb_features() {
	return mNbFeatures;
}

std::vector<unsigned char*>& SIFT_loader::get_descriptors() {
	return mDescriptors;
}

std::vector<SIFT_keypoint>& SIFT_loader::get_keypoints() {
	return mKeypoints;
}

bool SIFT_loader::load_Lowe_features(const char *filename) {
	//now open the .sift file and read out the interest points
	// format:
	//
	// nb_keypoints size_descriptor (should be 128)
	// for each keypoint:
	//	y x scale orientation(radians)
	//    descripor( size_descriptor many char values) (6 lines with 20 values, 1 with 8 values)
	//the coordinates of the interest points are stored in a coordinate system in which the origin corresponds to the upper left of the image

	std::ifstream instream(filename, std::ios::in);

	if (!instream.is_open())
		return false;

	// read the number of keypoints and the size of the descriptors
	uint32_t size_descriptor;
	instream >> mNbFeatures >> size_descriptor;

	if (size_descriptor != 128)
		return false;

	// load the keypoints and their descriptors
	mKeypoints.resize(mNbFeatures);
	mDescriptors.resize(mNbFeatures, 0);

	double x, y, scale, orientation;
	unsigned int descriptor_element;

	for (uint32_t i = 0; i < mNbFeatures; ++i) {
		mDescriptors[i] = new unsigned char[128];
		instream >> y >> x >> scale >> orientation;
		mKeypoints[i] = SIFT_keypoint(x, y, scale, orientation);

		// read the descriptor
		for (int j = 0; j < 128; ++j) {
			instream >> descriptor_element;
			mDescriptors[i][j] = (unsigned char) descriptor_element;
		}
	}

	instream.close();

	return true;
}