| // Copyright (c) 2022, ETH Zurich and UNC Chapel Hill. | |
| // All rights reserved. | |
| // | |
| // Redistribution and use in source and binary forms, with or without | |
| // modification, are permitted provided that the following conditions are met: | |
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| // * Redistributions in binary form must reproduce the above copyright | |
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| // * Neither the name of ETH Zurich and UNC Chapel Hill nor the names of | |
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| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
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| // | |
| // Author: Johannes L. Schoenberger (jsch-at-demuc-dot-de) | |
| 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 | |