Image Mosaic Research Articles

Using Gaia and synthetic photometry for the absolute flux calibration of planetary cameras: The case of the BepiColombo/SIMBIO-SYS

The absolute flux calibration of a planetary camera is pivotal for a quantitative analysis of the brightness that is reflected by a celestial body to a) characterise its microphysical properties, b) analyse changes caused by exogenic or endogenic activity, and c) produce high-quality image mosaics to understand the geology of the body. This is usually done by observing a few standard stars. We propose an alternative method that relies on the Gaia catalogue and consider the Spectrometer and Imagers for Mpo Bepicolombo Integrated Observatory SYStem (SIMBIO-SYS) suite of imagers on board BepiColombo, which is currently flying towards planet Mercury, as a test case. We discuss the advantages of this method and its implications for the future exploration of Mercury, as well as the applicability to other cameras. We evaluate whether Gaia low-resolution spectra (XPSP) are suitable to supply a set of reference stars for an absolute calibration of a planetary camera. We assess the performances of this approach and discuss its advantages with respect to more traditional methods. While this was validated for common astronomical facilities, it has never been used for planetary cameras. We used synthetic photometry from Gaia low-resolution (BP/RP) spectra to produce magnitudes in all the passbands of SIMBIO-SYS. We used a set of very reliable spectrophotometric standard stars to correct small residual systematics that affect externally calibrated BP/RP spectra, and we thus defined the SIMBIO-SYS photometric system tied to the flux scale of the CALSPEC spectrophotometric library. We evaluated the uncertainties on the final calibration of this photometric system by assessing the accuracy (average of the residuals) and precision (standard deviation of the residuals) of the reproduced magnitudes of stars in the CALSPEC spectrophotometric library. We find an accuracy better than 0.1<!PCT!> and a precision ranging from 0.4<!PCT!> to 1.0<!PCT!>, depending on the considered passband, in the magnitude and colour ranges that are relevant for stars that can be used as photometric standards for the SIMBIO-SYS instrument. Our results imply an improvement in the flux uncertainty through the absolute calibration of a factor 2-12 with respect to pre-existing imaging data of Mercury, and of a factor 2-7 with respect to the Colour and Stereo Surface Imaging System (CaSSIS), which is a similar camera with the same detector that orbits Mars, for which the absolute calibration details are available in the literature. In the context of the future exploration of Mercury, these improvements imply an unprecedented sensitivity of the SIMBIO-SYS instrument that will provide a novel view of the present-day surface activity on Mercury and of the photometric properties of the Hermean surface.

Mapping Paleolacustrine Deposits with a UAV-borne Multispectral Camera: Implications for Future Drone Mapping on Mars

NASA’s Ingenuity Mars Helicopter has marked a new era in planetary exploration by employing unmanned aerial vehicles (UAVs) to enhance our understanding of planetary surfaces. This study evaluates the potential of UAVs for mapping Martian environments, with Lake Natron, Tanzania, serving as an analog for Martian paleolakes. During two field seasons (2023 January and July), we used a Phantom 4 Pro drone equipped with a MicaSense RedEdge-M multispectral camera, supplemented by in situ analysis using a TerraSpec Halo VNIR-SWIR spectrometer, to capture high-resolution imagery and spectral data. Almost all image processing and analysis, except for image mosaic and digital elevation model (DEM) generation, was performed using Python scripting. We benchmarked the onboard image processing capabilities using a Raspberry Pi 5 single-board computer. Processing steps include digital number (DN)-to-radiance conversion, assessment of the best radiance-to-reflectance conversion method, image mosaic creation, DEM generation, calculation of optimal band indices, and selection of the best classification technique. The research underscores Lake Natron’s diverse lithologies as a suitable analog site and demonstrates significant improvements in classification when normalized elevation data are incorporated with spectral index maps through unsupervised classification methods. The study also addresses challenges related to high-resolution image transmission and processing, advocating for advanced techniques such as image compression and low-power computational models. Additionally, it highlights computational and power limitations as key obstacles, suggesting that emerging technologies such as photonic computing and hybrid controllers could provide viable solutions. These findings emphasize the transformative potential of UAVs in planetary exploration while outlining key areas for future research and technological development.

Efficient area coverage planning using approximation tiling heuristics for mosaic imaging with agile spacecraft

Efficient area coverage planning using approximation tiling heuristics for mosaic imaging with agile spacecraft

Performance Comparison of RANSAC and Other Model Estimation Methods in Panoramic Image Mosaic

As computer vision technology advances, the significance of outlier processing algorithms increases across various applications. Despite this, there is a lack of comprehensive comparisons to assess the performance of these algorithms. This paper focuses on evaluating the principles, advantages, and disadvantages of three key models: RANSAC, least squares, and lmed. Through experimental testing in diverse scenarios, the study identifies the most suitable model for different contexts. Results indicate that RANSAC exhibits the highest robustness against outliers, while lmed performs effectively with a moderate number of outliers. These findings are crucial for selecting appropriate models tailored to specific applications, ultimately enhancing the quality of panoramic mosaic images. The comparative analysis presented in this paper aims to guide practitioners in choosing the best outlier processing techniques based on their specific requirements and application environments, thereby improving the robustness and accuracy of computer vision systems.

SMILES Initial Data Release: Unveiling the Obscured Universe with MIRI Multiband Imaging

The James Webb Space Telescope is revolutionizing our view of the Universe through unprecedented sensitivity and resolution in the infrared, with some of the largest gains realized at its longest wavelengths. We present the Systematic Mid-infrared Instrument (MIRI) Legacy Extragalactic Survey (SMILES), an eight-band MIRI survey with Near-Infrared Spectrograph spectroscopic follow-up in the GOODS-S/HUDF region. SMILES takes full advantage of MIRI’s continuous coverage from 5.6 to 25.5 μm over an ∼34 arcmin2 area to greatly expand our understanding of the obscured Universe up to cosmic noon and beyond. This work, together with a companion paper by G. Rieke et al., covers the SMILES science drivers and technical design, early results with SMILES, data reduction, photometric catalog creation, and the first data release. As part of the discussion on early results, we additionally present a high-level science demonstration on how MIRI’s wavelength coverage and resolution will advance our understanding of cosmic dust using the full range of polycyclic aromatic hydrocarbon emission features from 3.3 to 18 μm. Using custom background subtraction, we produce robust reductions of the MIRI imaging that maximize the depths reached with our modest exposure times (∼0.6−2.2 ks per filter). Included in our initial data release are (1) eight MIRI imaging mosaics reaching depths of 0.2−18 μJy (5σ) and (2) a 5−25.5 μm photometric catalog with over 3000 sources. Building upon the rich legacy of extensive photometric and spectroscopy coverage of GOODS-S/HUDF from the X-ray to the radio, SMILES greatly expands our investigative power in understanding the obscured Universe.

A compact module for video-rate image mosaics in two-photon microscopy

A compact module for video-rate image mosaics in two-photon microscopy

INVESTIGATION OF THE POSSIBILITIES OF ENAMEL GRAINS FOR THE FORMATION OF MICROMOSAICS

The paper investigates the possibilities of grains from hot enamels for the formation of micromosaics. Enamel grain with a diameter of 0.4…5.0 mm is made from pieces of crushed hot enamels that acquire a spherical shape during firing in a muffle furnace or with the help of a gas burner flame. The mosaic image is formed by densely laying out on a metal base with an applied adhesive layer of enamel grains of the same or different diameter in accordance with the artistic idea. Enamel grain from hot enamels has high techno-logical and aesthetic characteristics characteristic of hot enamels: hardness, durability, wide colour palette, beautiful shine, etc. All this makes enamel grain a promising material for mosaic work. The technique of mi-cromosaic from enamel grains has the widest potential for decorating jewellery and art products, as it al-lows you to embody any design ideas.

U-net with ResNet-34 backbone for dual-polarized C-band baltic sea-ice SAR segmentation

Abstract In this study, the U-net with ResNet-34, i.e. a residual neural network with 34 layers, backbone semantic segmentation network is applied to C-band sea-ice SAR imagery over the Baltic Sea. Sentinel-1 Extra Wide Swath mode HH/HV-polarized SAR data acquired during the winter season 2018–2019, and corresponding segments derived from the daily Baltic Sea ice charts were used for training the segmentation algorithm. C-band SAR image mosaics of the winter season 2020–2021 were then used to evaluate the segmentation. The major objective was to study the suitability of semantic segmentation of SAR imagery for automated SAR segmentation and also to find a potential replacement for the outdated iterated conditional modes (ICM) algorithm currently in operational use. The results compared to the daily Baltic Sea ice charts and the operational ICM segmentation and visual interpretation were encouraging from the operational point of view. Open water areas were located very well and the oversegmentation produced by ICM was significantly reduced. The correspondence between the ice chart polygons and the segmentation results was also reasonably good. Based on the results, the studied method is a potential candidate to replace the operational ICM SAR segmentation used in the Copernicus Marine Service automated sea-ice products at Finnish Meteorological Institute.

The Sacred Scripture and the Symbolic Representations in the Early Christian Figurative Mosaics from the Balkans

It is a well-known fact that the figurative images in the Early Christian art are generally in conformity with the basic Sacraments, specific texts in the Old and the New Testament and the liturgy and rituals, which were performed in the churches. In the recent 40 years many new publications have been devoted to the pavement mosaics from the Balkans but they deal mainly with limited number of monuments from a separate contemporary state. As in Late Antiquity the borders between the provinces and both empires (Western and Eastern) were quite different from the contemporary ones, therefore the picture shown when tracing this aspect of research is not adequate and not complete if the we do not concern the ancient boundaries of the provinces, and do not consider the Balkans as one artistic area, but with many different traditions and influences. For this purpose, the mosaics not only from the well-known artistic centres of Greece have been gathered together, but also from Albania, Bulgaria, Macedonia and the European parts of Turkey. This provides new opportunities for a multifaceted study of the topic of the Early Byzantine liturgical practice from a formal, symbolic and theological point of view and emphasizes the importance of the figurative mosaic images and the inscriptions associated with them, which directly or symbolically reflects the Holy Scripture as well as it reveals the mysterious nature and the specific features of the rituals of the Early Christianity.

An Image-based Search for Pulsar Candidates in the MeerKAT Bulge Survey

We report on the results of an image-based search for pulsar candidates toward the Galactic bulge. We used mosaic images from the MeerKAT radio telescope that were taken as part of a 173 deg2 survey of the bulge and Galactic center of our Galaxy at L band (856–1712 MHz) in all four Stokes I, Q, U, and V. The image rms noise levels of 12–17 μJy ba−1 represent a significant increase in sensitivity over past image-based pulsar searches. Our primary search criterion was circular polarization, but we used other criteria, including linear polarization, in-band spectral index, compactness, variability, and multiwavelength counterparts to select pulsar candidates. We first demonstrate the efficacy of this technique by searching for polarized emission from known pulsars and comparing our results with measurements from the literature. Our search resulted in a sample of 75 polarized sources. Bright stars or young stellar objects were associated with 28 of these sources, including a small sample of highly polarized dwarf stars with pulsar-like steep spectra. Comparing the properties of this sample with the known pulsars, we identified 30 compelling candidates for pulsation follow-up, including two sources with both strong circular and linear polarization. The remaining 17 sources are either pulsars or stars, but we cannot rule out an extragalactic origin or image artifacts among the brighter, flat-spectrum objects.

Rapid Detection of Single Bacteria Using Filter-Array-Based Hyperspectral Imaging Technology.

Rapid and accurate detection of bacterial pathogens is crucial for preventing widespread public health crises, particularly in the food industry. Traditional methods are often slow and require extensive labeling, which hampers timely responses to potential threats. In response, we introduce a groundbreaking approach using filter-array-based hyperspectral imaging technology, enhanced by a super-resolution demosaicking technique. This innovative technology streamlines the detection process and significantly enhances the resolution of mosaic hyperspectral imaging. By utilizing a snapshot hyperspectral camera with a 15 ms integration time, it facilitates the identification of bacteria at the single-cell level without requiring chemical labels. The integration of a 3D convolutional neural network optimizes the recognition of pathogenic bacteria, achieving an impressive accuracy of 91.7%. Our approach dramatically improves the efficiency and effectiveness of bacterial detection, providing a promising solution for critical applications in public health and the food industry.

Atomic force microscopy wide-field scanning imaging using homography matrix optimization

During the offline combination of multiple atomic force microscopy (AFM) images, changes in probe displacement can be affected by dynamic noise, leading to dislocation and tearing in the stitching. To overcome this, we designed a homography matrix optimization method to describe the relative positional relationship between images by constructing the original image matrix and applying singular value decomposition to denoise the homography matrix. Additionally, we implemented a scale-invariant feature transform (SIFT) to extract feature points. To verify the effectiveness of this method, the SIFT + RANSAC (R), SIFT + affine transformation (AT), and oriented FAST and rotated BRIEF (ORB) algorithms were compared with the proposed algorithm. The experimental results demonstrate that the proposed method precisely computes the transformation matrix, thereby guaranteeing the geometric consistency of mosaic imaging. The proposed method preserves the intricate details of the original image and enhances the stitching quality of wide-field images.

Michael Tippett: Specification of the Work for Orchestra and Soprano "Byzantia"

The purpose of the research is to reveal the deep image-sound layers and features of the Irish bardic tradition in the work of M. Tippett through the prism of the work for orchestra and soprano "Byzantium". The methodological basis of the research is historical-conceptual, hermeneutic method and comparative analysis of factual data based on the works of Thomas Weiskel, David Clark, Edward Venn, and Meirion Bowen. Scientific novelty. For the first time in the Ukrainian art history segment, M. Tippett's work for orchestra and soprano "Byzantium" was analysed with an emphasis on the dramaturgy of the composition, cyclical elements, metaphorical sound images, symbolism and characteristic features of the musical and poetic tradition of Irish bards. Conclusions. Biographical collisions of M. Tippett influenced his creative aspirations and attitude to the surrounding world. M. Tippett's aesthetic views are a dialogue between romantic aspirations and sceptical realism of the modern era. Michael Tippett's musical language absorbed both tradition and the entire palette of accumulated world musical experience, as well as duality of meanings, symbolism, imagery and conflict. The work analyses the composition for orchestra and soprano "Byzantium" by M. Tippet, which is based on the mosaic of images, the logical sequence of musical motifs, and cyclicity. It is necessary to highlight the fragmentary nature of musical sections, variable motifs, the presence of contrasting material, the symbolism of magical, changing life force as secular ephemerality, the destruction of the musical text using the technique of expansion and fragmentation. Thus, the composition "Byzantium" is a reincarnation of Irish cultural nationalism in the aspect of traditional forms of bardic poetry. The musical language of M. Tippett in the work "Byzantium" is based on the forms crystallised by the work of L. Beethoven and updated by the musical context of modern and postmodern.

Accuracy Investigation on Orthophotos Produced from Digital Aerial Imagery Recorded from Different Altitudes

A digital orthophoto is a topographic image that has a fixed scale like a map and on which values such as coordinates and lengths can be read, which is obtained by eliminating the errors caused by tilts and rotations in aerial images and minimizing the point shifts caused by height differences in the terrain. Digital orthophotos offer more flexible, cost-effective, and higher-quality outputs than classical methods. There is no decrease in the quality of the image as in the analog technique, and it can also be presented quickly and easily in the digital environment. The geometrical accuracy of orthophoto maps used in geomatics applications is of even greater importance. This study compared the orthophoto maps, that have a fixed scale like maps, obtained from digital aerial photographs at a ground sample distance of 7, 15 and 25 cm in 2011 in the campus area of Aksaray University, in terms of their positional accuracy. Orthophoto mosaic images were created using “Erdas LPS” software. When the accuracy are compared, it was found that digital orthophoto maps produced at three different ground sample distances gave us similar results for standard techniques. It was also concluded that the positional accuracy of orthophoto maps for all three ground sample distances was suitable for use as reference and as a base in all application areas, except for those requiring very high accuracy.

Automatic tiling method for mosaic ceramic art images based on subpixel edge fitting localization and collaborative operation of multiple manipulators

Mosaic ceramics are not limited to use solely as building materials, they also possess artistic value. Artists can create images by arranging and combining mosaic ceramics, resulting in a perfect fusion of large-scale public art for external walls and ceramic materials. However, the current approach for artists to create mosaic ceramic exterior wall art images involves manual laying and assembling of individual mosaic ceramics. This manual process suffers from issues such as low efficiency, eye fatigue, selection errors, and the risk of high-altitude operations. These challenges significantly impact the quality and efficiency of creating mosaic ceramic exterior wall art image images. To address these problems, this paper proposes an automatic mosaic ceramic art image stitching method based on subpixel edge fitting positioning and collaborative operation of multiple robotic arms. Additionally, a new U + I type conveying method is designed for efficient and space-saving transportation of mosaic ceramics. Experimental results demonstrate a high success rate of recognition, absorption, and placement of multi-color mosaic ceramics using this method reaching 95.45%, with a positioning error within 0.5 mm. The method can also adapt to varying levels of light intensity or noise interference. This approach effectively enhances the quality and efficiency of creating mosaic ceramic exterior wall art images and promotes the development of mosaic ceramic exterior wall public art creation.

Autonomous Underwater Vehicle Navigation Enhancement by Optimized Side-Scan Sonar Registration and Improved Post-Processing Model Based on Factor Graph Optimization

Autonomous Underwater Vehicles (AUVs) equipped with Side-Scan Sonar (SSS) play a critical role in seabed mapping, where precise navigation data are essential for mosaicking sonar images to delineate the seafloor’s topography and feature locations. However, the accuracy of AUV navigation, based on Strapdown Inertial Navigation System (SINS)/Doppler Velocity Log (DVL) systems, tends to degrade over long-term mapping, which compromises the quality of sonar image mosaics. This study addresses the challenge by introducing a post-processing navigation method for AUV SSS surveys, utilizing Factor Graph Optimization (FGO). Specifically, the method utilizes an improved Fourier-based image registration algorithm to generate more robust relative position measurements. Then, through the integration of these measurements with data from SINS, DVL, and surface Global Navigation Satellite System (GNSS) within the FGO framework, the approach notably enhances the accuracy of the complete trajectory for AUV missions. Finally, the proposed method has been validated through both the simulation and AUV marine experiments.

The JWST UNCOVER Treasury Survey: Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization

In this paper we describe the survey design for the Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization (UNCOVER) Cycle 1 JWST Treasury program, which executed its early imaging component in 2022 November. The UNCOVER survey includes ultradeep (∼29–30AB) imaging of ∼45 arcmin2 on and around the well-studied A2744 galaxy cluster at z = 0.308 and will follow up ∼500 galaxies with extremely deep low-resolution spectroscopy with the NIRSpec/PRISM during the summer of 2023, with repeat visits in summer 2024. We describe the science goals, survey design, target selection, and planned data releases. We also present and characterize the depths of the first NIRCam imaging mosaic, highlighting previously unparalleled resolved and ultradeep 2–4 μm imaging of known objects in the field. The UNCOVER primary NIRCam mosaic spans 28.8 arcmin2 in seven filters (F115W, F150W, F200W, F277W, F356W, F410M, and F444W) and 16.8 arcmin2 in our NIRISS parallel (F115W, F150W, F200W, F356W, and F444W). To maximize early community use of the Treasury data set, we publicly release the full reduced mosaics of public JWST imaging including 45 arcmin2 NIRCam and 17 arcmin2 NIRISS mosaics on and around the A2744 cluster, including the Hubble Frontier Field primary and parallel footprints.

Candidate Distant Trans-Neptunian Objects Detected by the New Horizons Subaru TNO Survey

We report the detection of 239 trans-Neptunian objects discovered through the ongoing New Horizons survey for distant minor bodies being performed with the Hyper Suprime-Cam mosaic imager on the Subaru Telescope. These objects were discovered in images acquired with either the r2 or the recently commissioned EB-gri filter using shift and stack routines. Due to the extremely high stellar density of the search region downstream of the spacecraft, new machine learning techniques had to be developed to manage the extremely high false-positive rate of bogus candidates produced from the shift and stack routines. We report discoveries as faint as r2 ∼ 26.5. We highlight an overabundance of objects found at heliocentric distances R ≳ 70 au compared to expectations from modeling of the known outer solar system. If confirmed, these objects betray the presence of a heretofore-unrecognized abundance of distant objects that can help explain a number of other observations that otherwise remain at odds with the known Kuiper Belt, including detections of serendipitous stellar occultations, and recent results from the Student Dust Counter on board the New Horizons spacecraft.

A UAV Thermal Imaging Format Conversion System and Its Application in Mosaic Surface Microthermal Environment Analysis.

UAV thermal infrared remote sensing technology, with its high flexibility and high temporal and spatial resolution, is crucial for understanding surface microthermal environments. Despite DJI Drones' industry-leading position, the JPG format of their thermal images limits direct image stitching and further analysis, hindering their broad application. To address this, a format conversion system, ThermoSwitcher, was developed for DJI thermal JPG images, and this system was applied to surface microthermal environment analysis, taking two regions with various local zones in Nanjing as the research area. The results showed that ThermoSwitcher can quickly and losslessly convert thermal JPG images to the Geotiff format, which is further convenient for producing image mosaics and for local temperature extraction. The results also indicated significant heterogeneity in the study area's temperature distribution, with high temperatures concentrated on sunlit artificial surfaces, and low temperatures corresponding to building shadows, dense vegetation, and water areas. The temperature distribution and change rates in different local zones were significantly influenced by surface cover type, material thermal properties, vegetation coverage, and building layout. Higher temperature change rates were observed in high-rise building and subway station areas, while lower rates were noted in water and vegetation-covered areas. Additionally, comparing the temperature distribution before and after image stitching revealed that the stitching process affected the temperature uniformity to some extent. The described format conversion system significantly enhances preprocessing efficiency, promoting advancements in drone remote sensing and refined surface microthermal environment research.

Binary craters on Ceres and Vesta and implications for binary asteroids

Context. Airless planetary objects have their surfaces covered by craters, and these can be used to study the characteristics of asteroid populations. Planetary surfaces present binary craters that are associated with the synchronous impact of binary asteroids. Aims. We identify binary craters on asteroids (1) Ceres and (4) Vesta, and aim to characterize the properties (size ratio and orbital plane) of the binary asteroids that might have formed them. Methods. We used global crater databases developed in previous studies and mosaics of images from the NASA DAWN mission high-altitude and low-altitude mapping orbits. We established selection criteria to identify craters that were most likely a product of the impact of a binary asteroid. We performed numerical simulations to predict the orientation of the binary craters assuming the population of impactors has mutual orbits coplanar with heliocentric orbits, as the current census of binary asteroids suggests. We compared our simulations with our survey of binary craters on Ceres and Vesta through a Kolmogorov-Smirnov test. Results. We find geomorphological evidence of 39 and 18 synchronous impacts on the surfaces of Ceres and Vesta, respectively. The associated binary asteroids are widely separated and similar in diameter. The distributions of the orientation of these binary craters on both bodies are statistically different from numerical impact simulations that assume binary asteroids with coplanar mutual and heliocentric orbits. Conclusions. Although the identification of binary craters on both bodies and the sample size are limited, these findings are consistent with a population of well-separated and similarly sized binary asteroids with nonzero obliquity that remains to be observed, in agreement with the population of binary craters identified on Mars.