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Xiao-Ping Lu

Publications and source records attributed to Xiao-Ping Lu.

4 recordsLinked to original sources

History-Augmented Contrastive Learning With Soft Mixture of Experts for Blind Super-Resolution of Planetary Remote Sensing Images

Blind Super-Resolution (BSR) in planetary remote sensing constitutes a highly ill-posed inverse problem, characterized by unknown degradation patterns and a complete absence of ground-truth supervision. Existing unsupervised approaches often struggle with optimization instability and distribution shifts, relying on greedy strategies or generic priors that fail to preserve distinct morphological semantics. To address these challenges, we propose History-Augmented Contrastive Mixture of Experts (HAC-MoE), a novel unsupervised framework that decouples kernel estimation from image reconstruction without external kernel priors. The framework is founded on three key innovations: (1) A Contrastive Kernel Sampling mechanism that mitigates the distribution bias inherent in random Gaussian sampling, ensuring the generation of plausible kernel priors via similarity constraints; (2) A History-Augmented Contrastive Learning strategy that leverages historical model states as negative self-priors. We provide a theoretical analysis demonstrating that this mechanism induces strong convexity in the feature space, thereby stabilizing the unsupervised optimization trajectory and preventing overfitting; and (3) A Morphology-Aware Soft Mixture-of-Experts (MA-MoE) estimator that dynamically modulates spectral-spatial features to adaptively reconstruct diverse planetary topographies. To facilitate rigorous evaluation, we introduce Ceres-50, a benchmark dataset encapsulating diverse geological features under realistic degradation simulations. Extensive experiments demonstrate that HAC-MoE achieves state-of-the-art performance in reconstruction quality and kernel estimation accuracy, offering a solution for scientific observation in data-sparse extraterrestrial environments.

cs.CV

Spectral Deconvolution Analysis on Olivine-Orthopyroxene Mixtures with Simulated Space Weathering Modifications

Olivine and pyroxene are important mineral end-members for studying the sur-face material compositions of mafic bodies. The profiles of visible and near-infraredspectra of olivine-orthopyroxene mixtures systematically varied with their compositionratios. In our experiments, we combine the RELAB spectral database with a new spec-tral data obtained from some assembled olivine-orthopyroxene mixtures. We found thatthe commonly-used band area ratio (BAR, Cloutis et al. 1986) does not work well onour newly obtained spectral data. To investigate this issue, an empirical procedure basedon fitted results by modified Gaussian model is proposed to analyze the spectral curves.Following the new empirical procedure, the end-member abundances can be estimatedwith a 15% accuracy with some prior mineral absorption features. In addition, the mix-ture samples configured in our experiments are also irradiated by pulsed lasers to simulateand investigate the space weathering effects. Spectral deconvolution results confirm thatlow-content olivine on celestial bodies are difficult to measure and estimate. Therefore,the olivine abundance of space weathered materials may be underestimated from remotesensing data. This study may be used to quantify the spectral relationship of olivine-orthopyroxene mixtures and further reveal their correlation between the spectra of ordi-nary chondrites and silicate asteroids.

astro-ph.EP

Study of the Modified Gaussian Model on olivine diagnostic spectral features and its applications in space weathering experiments

The absorption features of olivine in visible and near-infrared (VNIR) reflectance spectra are the key spectral parameters in its mineralogical studies. Generally, these spectral parameters can be obtained by exploiting the Modified Gaussian Model (MGM) with a proper continuum removal. However, different continua may change the deconvolution results of these parameters. This paper investigates the diagnostic spectral features of olivine with diverse chemical compositions. Four different continuum removal methods with MGM for getting the deconvolution results are presented and the regression equations for predicting the Mg-number (Fo#) are introduced. The results show that different continua superimposed on the mineral absorption features will make the absorption center shift, as well as the obvious alterations in shape, width, and strength of the absorption band. Additionally, it is also found that the logarithm of a second-order polynomial continuum can match the overall shape of the spectrum in logarithmic space, and the improved regression equations applied to estimate the chemical composition of olivine-dominated spectra also have a better performance. As an application example, the improved approach is applied to pulse laser irradiated olivine grains to simulate and study the space weathering effects on olivine diagnostic spectral features. The experiments confirm that space weathering can make the absorption band center shift toward longer wavelength. Therefore, the Fo# estimated from remote sensing spectra may be less than its actual chemical composition. These results may provide valuable information for revealing the difference between the spectra of olivine grains and olivine-dominated asteroids.

astro-ph.IM

Dependence of Lightcurves on Phase Angle and Asteroid Shape

We investigate the phase angle dependence of asteroid lightcurves using numerical scattering models applied to simple body shapes. For simplicity, the Kaasalainen scattering parameters are obtained from the corresponding Hapke scattering laws for C-type, S-type, and V-type asteroids. The spectral types differ substantially in the role of multiple scattering (which is largely a function of their geometric albedos) but we find that the differences on the light curve vs.~phase relations are modest. By using a Kaasalainen scattering law, the amplitudes and axis ratios with respect to different phase angles from $0^\circ$ to $140^\circ$ are plotted for these types asteroids based on a biaxial ellipsoid shape model. Additionally, we examine the relationship between amplitude and axis ratio for a contact binary represented by identical biaxial ellipsoids, including the effects of shadowing of one component by the other. We compare the models with published high phase angle observations, and with interstellar object 1I/`Oumuamua ($Δm = 2.5$ magnitude at phase angle $α= 23^\circ$), finding axis ratio $5.2:1$ if represented as a single ellipsoid and $3.5:1$ for each component if represented as a nose-to-nose contact binary. While a detailed fit is not attempted, the comparison shows that the single ellipsoid model is better.

astro-ph.EP