High-resolution Mosaic Research Articles

A Census of the Deep Radio Sky with the VLA. I. 10 GHz Survey of the GOODS-N Field*

Abstract We present the first high-resolution, high-frequency radio continuum survey that fully maps an extragalactic deep field: the 10 GHz survey of the Great Observatories Origins Deep Survey-North (GOODS-N) field. This is a Large Program of the Karl G. Jansky Very Large Array (VLA) that allocated 380 hr of observations using the X-band (8–12 GHz) receivers, leading to a 10 GHz mosaic of the GOODS-N field with an average rms noise σ n = 671 nJy beam−1 and angular resolution θ 1/2 = 0.″22 across 297 arcmin2. To maximize the brightness sensitivity we also produce a low-resolution mosaic with θ 1/2 = 1.″0 and σ n = 968 nJy beam−1, from which we derive our master catalog containing 256 radio sources detected with peak signal-to-noise ratio ≥ 5. Radio source size and flux density estimates from the high-resolution mosaic are provided in the master catalog as well. The total fraction of spurious sources in the catalog is 0.75%. Monte Carlo simulations are performed to derive completeness corrections of the catalog. We find that the 10 GHz radio source counts in the GOODS-N field agree, in general, with predictions from numerical simulations/models and expectations from 1.4 and 3 GHz radio counts.

The many ages of Triton: New crater counts on the Voyager high-resolution image sequence and implications for impactor provenance

Triton is sparsely cratered overall, but because of the high concentration of its impact craters on the leading hemisphere of motion, a dominantly prograde planetocentric origin for the impactors has been hypothesized. With only a modest heliocentric contribution, the average age of Triton's datable terrains could be no more than ∼10 Ma, which would make Triton the most globally active icy satellite of all. This is obviously important, but is it true? There are clear stratigraphic age differences between terrains on Triton's leading hemisphere, especially on the 10-frame high-resolution Voyager 2 mosaic, which complicates simple or facile interpretations of the crater spatial distribution. Moreover, crater counts on the high-resolution mosaic, which we present here, indicate a steep slope for the impactor size-frequency distribution (SFD) at small (sub-km) sizes, completely at odds with crater counts on Charon, nominally the best estimate of the time-integrated Kuiper belt flux (Charon's corresponding SFD slope being quite shallow in comparison). Most likely, this implies that the smaller craters we measure on Triton are indeed predominantly planetocentric, but the origin of such a geologically recent prograde impactor swarm is puzzling. Here we consider several possible sources or explanations in detail, and find debris from a collision or collisions between neptunian irregular satellites to be the least objectionable, albeit unproven. Secondaries or sesquinaries from a large but unknown crater elsewhere on Triton are a distinct alternative.

Monitoring the seagrass ecosystem using the unmanned aerial vehicle (UAV) in coastal water of Jepara

Seagrass ecosystem in the world were highly sensitive to environmental changes. They were also in global decline and under threat from a variety of anthropogenic factors and global climate change. There was now an urgency to establish robust monitoring methodologies so that changed in seagrass abundance and distribution in these sensitive coastal environments can be understood. Typical monitoring approaches have included remote sensing from satellites and airborne platform, ground base ecological survey. The techniques can suffer from temporal and spatial inconsistency, or were very localised, making it hard to assess seagrass meadows in a structurer manner. The aim of this research was to present the technique of using a lightweight drone and consumer grade cameras to produce very high spatial resolution mosaic of intertidal site in Bandengan, Jepara waters, Indonesia. The data collection methodologies followed by digitation method techniques to produce coverage estimates, with ground check at location, with data drone analysis. This result showed that digitation method can show between the observed and classified low coverage seagrass 7-12% (<25%) compare to middle coverage seagrass 34-48% (between 25< and <50%), also was able to detect the other biotic features, such as colonies of macroalgae, massive coral, the flat sand and coral rubble at the observation location.

A high-resolution global basemap of (101955) Bennu

In early 2019, NASA's OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) mission surveyed asteroid (101955) Bennu with a collection of instruments, including the OSIRIS-REx Camera Suite (OCAMS) PolyCam imager. Using PolyCam panchromatic images, we constructed a globally controlled basemap of Bennu at an approximate ground sample distance of 5 cm with a mean spatial accuracy of ~30 cm. The basemap was photometrically normalized using a Minneart phase angle correction. New mapping methods were developed to combine images of Bennu's irregular shape and extremely rough surface into a nearly seamless mosaic. Here we present the global basemap of Bennu and discuss the image processing techniques used to construct a high-resolution mosaic of an irregular small body.

Rapid High-Resolution Mosaic Acquisition for Photoacoustic Remote Sensing.

Mechanical stages are routinely used to scan large expanses of biological specimens in photoacoustic imaging. This is primarily due to the limited field of view (FOV) provided by optical scanning. However, stage scanning becomes impractical at higher scanning speeds, or potentially unfeasible with heavier samples. Also, the slow scan-rate of the stages makes high resolution scanning a time-consuming process. Some clinical applications such as microsurgery require submicron resolution in a reflection-mode configuration necessitating a method that can acquire large field of views with a small raster scanning step size. In this study, we describe a method that combines mechanical stages with optical scanning for the rapid acquisition of high-resolution large FOVs. Optical scanning is used to acquire small frames in a two-dimensional grid formed by the mechanical stages. These frames are captured with specific overlap for effective image registration. Using a step size of 200 nm, we demonstrate mosaics of carbon fiber networks with FOVs of 0.8 × 0.8 mm2 captured in under 70 s with 1.2 µm image resolution. Larger mosaics yielding an imaging area of 3 × 3 mm2 are also shown. The method is validated by imaging a 1 × 1 mm2 section of unstained histopathological human tissue.

Backscattering Raman measurements using a broadband and high-resolution mosaic grating spatial heterodyne Raman spectrometer

Backscattering Raman measurements using a broadband and high-resolution mosaic grating spatial heterodyne Raman spectrometer

A High-resolution Mosaic of the Neutral Hydrogen in the M81 Triplet

Abstract We present a 3° × 3°, 105-pointing, high-resolution neutral hydrogen (H i) mosaic of the M81 galaxy triplet, (including the main galaxies M81, M82, and NGC 3077, as well as dwarf galaxy NGC 2976) obtained with the Very Large Array C and D arrays. This H i synthesis mosaic uniformly covers the entire area and velocity range of the triplet. The observations have a resolution of ∼20″ or ∼420 pc. The data reveal many small-scale anomalous velocity features highlighting the complexity of the interacting M81 triplet. We compare our data with Green Bank Telescope observations of the same area. This comparison provides evidence for the presence of a substantial reservoir of low-column density gas in the northern part of the triplet, probably associated with M82. Such a reservoir is not found in the southern part. We report a number of newly discovered kpc-sized low-mass H i clouds with H i masses of a few times 106 M ⊙. A detailed analysis of their velocity widths show that their dynamical masses are much larger than their baryonic masses, which could indicate the presence of dark matter if the clouds are rotationally supported. However, due to their spatial and kinematical association with H i tidal features, it is more likely that the velocity widths indicate tidal effects or streaming motions. We do not find any clouds that are not associated with tidal features down to an H i mass limit of a few times 104 M ⊙. We compare the H i column densities with resolved stellar density maps and find a star formation threshold around 3–6 × 1020 cm−2. We investigate the widths of the H i velocity profiles in the triplet and find that extreme velocity dispersions can be explained by a superposition of multiple components along the line of sight near M81 as well as winds or outflows around M82. The velocity dispersions found are high enough that these processes could explain the linewidths of damped-Lyα absorbers observed at high redshift.

Evaluation of Spatial Errors of Precipitation Rates and Types from TRMM Spaceborne Radar over the Southern CONUS

Abstract In this paper, the authors estimate the uncertainty of the rainfall products from NASA and Japan Aerospace Exploration Agency's (JAXA) Tropical Rainfall Measurement Mission (TRMM) Precipitation Radar (PR) so that they may be used in a quantitative manner for applications like hydrologic modeling or merging with other rainfall products. The spatial error structure of TRMM PR surface rain rates and types was systematically studied by comparing them with NOAA/National Severe Storms Laboratory's (NSSL) next generation, high-resolution (1 km/5 min) National Mosaic and Multi-Sensor Quantitative Precipitation Estimation (QPE; NMQ/Q2) over the TRMM-covered continental United States (CONUS). Data pairs are first matched at the PR footprint scale (5 km/instantaneous) and then grouped into 0.25° grid cells to yield spatially distributed error maps and statistics using data from December 2009 through November 2010. Careful quality control steps (including bias correction with rain gauges and quality filtering) are applied to the ground radar measurements prior to considering them as reference data. The results show that PR captures well the spatial pattern of total rainfall amounts with a high correlation coefficient (CC; 0.91) with Q2, but this decreases to 0.56 for instantaneous rain rates. In terms of precipitation types, Q2 and PR convective echoes are spatially correlated with a CC of 0.63. Despite this correlation, PR's total annual precipitation from convection is 48.82% less than that by Q2, which points to potential issues in the PR algorithm's attenuation correction, nonuniform beam filling, and/or reflectivity-to-rainfall relation. Finally, the spatial analysis identifies regime-dependent errors, in particular in the mountainous west. It is likely that the surface reference technique is triggered over complex terrain, resulting in high-amplitude biases.

Advanced Mass Calibration and Visualization for FT-ICR Mass Spectrometry Imaging

Mass spectrometry imaging by Fourier transform ion cyclotron resonance (FT-ICR) yields hundreds of unique peaks, many of which cannot be resolved by lower performance mass spectrometers. The high mass accuracy and high mass resolving power allow confident identification of small molecules and lipids directly from biological tissue sections. Here, calibration strategies for FT-ICR MS imaging were investigated. Sub-parts-per-million mass accuracy is demonstrated over an entire tissue section. Ion abundance fluctuations are corrected by addition of total and relative ion abundances for a root-mean-square error of 0.158 ppm on 16,764 peaks. A new approach for visualization of FT-ICR MS imaging data at high resolution is presented. The "Mosaic Datacube" provides a flexible means to visualize the entire mass range at a mass spectral bin width of 0.001 Da. The high resolution Mosaic Datacube resolves spectral features not visible at lower bin widths, while retaining the high mass accuracy from the calibration methods discussed.

Mosaicing of camera-captured document images

In this paper, we present a method for composing document mosaics from camera-captured images. We decompose the complexity of solving the 8-dof transformation between image pairs into two problems, that is, rectification and registration. This is achievable under a key assumption that sufficient text content forms orthogonal texture flows on the document surface. First, perspective distortion and rotation are removed from images using the texture flow information. Next, the translation and scaling are resolved by a Hough transform-like voting method. In the image composition part, our contribution is a sharpness based selection process which composes a seamless and blur free mosaic for text content. Experiments show that our approach can produce an accurate, sharp, and high resolution mosaic of a full document page from small image patches captured by a camera with various zooms and poses.

Pan–tilt–zoom camera calibration and high-resolution mosaic generation

In this paper, we discuss the problem of estimating parameters of a calibration model for active pan–tilt–zoom cameras. The variation of the intrinsic parameters of each camera over its full range of zoom settings is estimated through a two step procedure. We first determine the intrinsic parameters at the camera’s lowest zoom setting very accurately by capturing an extended panorama. The camera intrinsics and radial distortion parameters are then determined at discrete steps in a monotonically increasing zoom sequence that spans the full zoom range of the camera. Our model incorporates the variation of radial distortion with camera zoom. Both calibration phases are fully automatic and do not assume any knowledge of the scene structure. High-resolution calibrated panoramic mosaics are also computed during this process. These fully calibrated panoramas are represented as multi-resolution pyramids of cube-maps. We describe a hierarchical approach for building multiple levels of detail in panoramas, by aligning hundreds of images captured within a 1–12× zoom range. Results are shown from datasets captured from two types of pan–tilt–zoom cameras placed in an uncontrolled outdoor environment. The estimated camera intrinsics model along with the cube-maps provides a calibration reference for images captured on the fly by the active pan–tilt–zoom camera under operation making our approach promising for active camera network calibration.

A non-contact method of capturing low-resolution text for OCR

Document recognition is a lively research area with much effort concentrated on optical character recognition. Less attention is paid to locating and extracting text from the general (non-desktop, non-scanner) environment. Such contact-free extraction of text from a general scene has applications in the context of wearable computing, robotic vision, point and click document capture, or as an aid for visually handicapped people. Here, a novel automatic text reading system is introduced using an active camera focused on text regions already located in the scene (using our recent work). Initially, a located region of text is analysed to determine the optimal zoom that would foveate onto it. Then a number of images are captured over the text region to construct a high-resolution mosaic composite of the whole region. This magnified image of the text is suitable for reading by humans or for recognition by OCR, or even for text-to speech synthesis. Although we employed a low resolution camera, we still obtained very good results.

A high‐resolution magnetic mosaic at the Kyme archaeological site (Turkey)

AbstractAn extended high‐resolution magnetic investigation was undertaken at the archaeological site in Kyme (Turkey). In order to obtain highly resolved digital raster images, the gradient data sets were processed by using digital image processing techniques. In addition to these sets of data, the magnetic field measurements acquired by the bottom sensor alone were also processed. A careful comparison between the gradient data magnetograms and the bottom sensor magnetograms revealed how the entire mosaic, elaborated by processing the bottom sensor data, could fruitfully integrate and improve the information inferred by the vertical gradient magnetograms. Finally, the main archaeological features outlined from this magnetic investigation, as well as the results of a first guided excavation, are presented. Copyright © 2003 John Wiley &amp; Sons, Ltd.

JERS-1 SAR mosaics of Southeast Asia using calibrated path images

We have produced a continent-scale, high-resolution radar mosaic of Southeast Asia using L-band Synthetic Aperture Radar (SAR) data collected by Japanese Earth Resources Satellite-1 (JERS-1). This 100 m resolution, 16-bit mosaic dataset of the backscattering coefficients has a calibration accuracy of 1.1 dB, geometric accuracy of 406 m, and an image quality similar to those of Amazon and central Africa previously produced by NASA Jet Propulsion Laboratory (JPL) and the Joint Research Center (JRC) of the European Commission (EC). This dataset may be beneficial in Earth observation research, especially for forest monitoring, because the L-band signal is sensitive to forest characteristics. This paper introduces a new mosaicking method that was developed to assemble the SAR path images into a large-scale mosaic, a way to recalibrate the radiometric imbalance across paths, and the validation.

Global color and albedo variations on Io

Three multispectral mosaics of Io have been produced from Voyager imaging data: a global mosaic from each of the Voyager 1 and Voyager 2 data sets and a high-resolution mosaic of the region surrounding the volcano Ra Patera. The mosaics are maps of normal albedo and color in accurate geometric map formats. Io's photometric behavior, mapped with a two-image technique, is spatially variable, especially in the bright white areas. The disk-integrated color and albedo of the satellite have been remarkably constant over recent decades, despite the volcanic activity and the many differences between Voyager 1 and 2 images (acquired just 4 months apart). This constancy is most likely due to the consistent occurrence of large Pele-type plumes with relatively dark, red deposits in the region from long 240 to 360°. A transient brightening southeast of Pele during the Voyager 1 encounter was probably due to real changes in surface and/or atmospheric materials, rather than to photometric behavior. The intrinsic spectral variability of Io, as seen in a series of two-dimensional histograms of the multispectral mosaics, consists of continuous variation among three major spectral end members. The data were mapped into five spectral units to compare them with laboratory measurements of candidate surface materials and to show the planimetric distributions. Unit 1 is best fit by the spectral reflectance of ordinary elemental sulfur, and it is closely associated with the Peletype plume deposits. Unit 2 is strongly confined to the polar caps above about latitude ±50°, but its composition is unknown. Unit 5 is probably SO 2 with relatively minor contamination; it is concentrated in the equatorial region and near the long-lived Prometheus-type plumes. Units 3 and 4 are gradational between units 1 and 5. In addition to SO 2 and elemental sulfur, other plausible components of the surface are polysulfur oxides, FeCl 2, Na 2S, and NaHS.