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Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI).

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Improved algorithm for tree height extraction based on sparse and dense image matching with epipolar constraints

CAI Xiangyuan, CHEN Xiaotong, LI Ronghao, WEI Jiangnan, LI Shuai, ZHAO Hongying

, Available online , doi: 10.12265/j.gnss.2023221

[Abstract](12) [FullText HTML] (4) [PDF 3018KB](0)

Abstract:
Tree height is a crucial parameter for monitoring forest conditions,and photogrammetry stands out as an essential method for tree height acquisition due to its low cost and flexibility. As a passive remote sensing approach, the traditional photogrammetric method often requires a substantial quantity of images with high overlap, which is associated with the sparsity of traditional image features. To enhance tree height extraction accuracy under limited image availability, a proposed approach combines sparse feature matching with dense pixel matching, by employing the epipolar constraint to filter outliers, dense and highly accurate matching results are obtained. The three-dimensional reconstruction algorithm is then applied to generate a point cloud representing the forest scene. This method demonstrates the capability to reconstruct the forest scene comprehensively and extract tree heights even with a small number of images. Comparison with results from LiDAR point clouds yields a correlation coefficient of 0.91 and a maximum error of 1.64 meters. Notably, the algorithm requires only a small number of overlapping images, indicating its potential in handling high-resolution satellite imagery.

Architecture design of radiation source positioning system based on TDOA

HU Anyi, WANG Dengliang, QIN Bingkun, ZHANG Faxiang

, Available online , doi: 10.12265/j.gnss.2023174

[Abstract](73) [FullText HTML] (42) [PDF 2726KB](7)

Abstract:
To ensure the normal application of the Global Navigation Satellite System (GNSS), monitoring and localization of GNSS interference radiation sources are required. This paper presents the design of a radiation source positioning system architecture. By designing the system functions, architecture, grid monitoring equipment and workflows, high-precision time synchronization and reliable time difference measurements are achieved using BeiDou/GPS timing + high-stability crystal oscillators and a generalized weighted time delay estimation algorithm, which ensures the accuracy of time difference of arrival (TDOA) localization. The effective location of radiation source is realized through system application test.