Post-Processing Resolution Enhancement of Open Skies Photographic Imagery

The Treaty on Opens Skies allows any signatory nation to fly a specifically equipped reconnaissance aircraft anywhere over the territory of any other signatory nation. For photographic images, this treaty allows for a maximum ground resolution of 30 cm. The National Air Intelligence Center (NAIC), which manages implementation of the Open Skies Treaty for the US Air Force, wants to determine if post-processing of the photographic images can improve spatial resolution beyond 30 cm, and if so, determine the improvement achievable. Results presented in this thesis show that standard linear filters (edge and sharpening) do not improve resolution significantly and that super-resolution techniques are necessary. Most importantly, this thesis describes a prior- knowledge model fitting technique that improves resolution beyond the 30 cm treaty limit. The capabilities of this technique are demonstrated for a standard 3-Bar target, an optically degraded 2-Bar target, and the USAF airstar emblem

Spacecraft Position Estimation and Attitude Determination using Terrestrial Illumination Matching

An algorithm to conduct spacecraft position estimation and attitude determination via terrestrial illumination matching (TIM) is presented consisting of a novel method that uses terrestrial lights as a surrogate for star fields. Although star sensors represent a highly accurate means of attitude determination with considerable spaceflight heritage, with Global Positioning System (GPS) providing position, TIM provides a potentially viable alternative in the event of star sensor or GPS malfunction or performance degradation. The research defines a catalog of terrestrial light constellations, which are then implemented within the TIM algorithm for position acquisition of a generic spacecraft bus. With the algorithm relying on terrestrial lights rather than the established standard of star fields, a series of sensitivity studies are showcased to determine performance during specified operating constraints, to include varying orbital altitude and cloud cover conditions. The pose is recovered from the matching techniques by solving the epipolar constraint equation using the Essential and Fundamental matrix, and point-to-point projection using the Homography matrix. This is used to obtain relative position change and the spacecraft\u27s attitude when there is a measurement. When there is not, both an extended and an unscented Kalman filter are applied to test continuous operation between measurements. The research is operationally promising for use with each nighttime pass, but filtering is not enough to sustain orbit determination during daytime operations

Integrated navigation and visualisation for skull base surgery

Skull base surgery involves the management of tumours located on the underside of the brain and the base of the skull. Skull base tumours are intricately associated with several critical neurovascular structures making surgery challenging and high risk. Vestibular schwannoma (VS) is a benign nerve sheath tumour arising from one of the vestibular nerves and is the commonest pathology encountered in skull base surgery. The goal of modern VS surgery is maximal tumour removal whilst preserving neurological function and maintaining quality of life but despite advanced neurosurgical techniques, facial nerve paralysis remains a potentially devastating complication of this surgery. This thesis describes the development and integration of various advanced navigation and visualisation techniques to increase the precision and accuracy of skull base surgery. A novel Diffusion Magnetic Resonance Imaging (dMRI) acquisition and processing protocol for imaging the facial nerve in patients with VS was developed to improve delineation of facial nerve preoperatively. An automated Artificial Intelligence (AI)-based framework was developed to segment VS from MRI scans. A user-friendly navigation system capable of integrating dMRI and tractography of the facial nerve, 3D tumour segmentation and intraoperative 3D ultrasound was developed and validated using an anatomically-realistic acoustic phantom model of a head including the skull, brain and VS. The optical properties of five types of human brain tumour (meningioma, pituitary adenoma, schwannoma, low- and high-grade glioma) and nine different types of healthy brain tissue were examined across a wavelength spectrum of 400 nm to 800 nm in order to inform the development of an Intraoperative Hypserpectral Imaging (iHSI) system. Finally, functional and technical requirements of an iHSI were established and a prototype system was developed and tested in a first-in-patient study

Hyperspectral Imaging from Ground Based Mobile Platforms and Applications in Precision Agriculture

This thesis focuses on the use of line scanning hyperspectral sensors on mobile ground based platforms and applying them to agricultural applications. First this work deals with the geometric and radiometric calibration and correction of acquired hyperspectral data. When operating at low altitudes, changing lighting conditions are common and inevitable, complicating the retrieval of a surface's reflectance, which is solely a function of its physical structure and chemical composition. Therefore, this thesis contributes the evaluation of an approach to compensate for changes in illumination and obtain reflectance that is less labour intensive than traditional empirical methods. Convenient field protocols are produced that only require a representative set of illumination and reflectance spectral samples. In addition, a method for determining a line scanning camera's rigid 6 degree of freedom (DOF) offset and uncertainty with respect to a navigation system is developed, enabling accurate georegistration and sensor fusion. The thesis then applies the data captured from the platform to two different agricultural applications. The first is a self-supervised weed detection framework that allows training of a per-pixel classifier using hyperspectral data without manual labelling. The experiments support the effectiveness of the framework, rivalling classifiers trained on hand labelled training data. Then the thesis demonstrates the mapping of mango maturity using hyperspectral data on an orchard wide scale using efficient image scanning techniques, which is a world first result. A novel classification, regression and mapping pipeline is proposed to generate per tree mango maturity averages. The results confirm that maturity prediction in mango orchards is possible in natural daylight using a hyperspectral camera, despite complex micro-illumination-climates under the canopy

Remote Sensing of Nearshore Hydrodynamic and Morphodynamic Processes

The use of remote sensing techniques in coastal science and engineering has rapidly increased in the past few decades. This dissertation outlines new remote sensing tools using two remote sensing technologies (lidar and X-band marine radar) along with two nearshore hydrodynamic and morphodynamic analyses supported or motivated by these remote sensing observations. The thesis is organized in manuscript format and contains four manuscripts as individual chapters. The first and last chapters of the thesis serve as the Introduction and Conclusions to the central four chapters. In the first manuscript (Chapter 2), a recently-established, permanent coastal lidar station in Duck, NC is presented. This system marks the first continuously-scanning and fully-automated nearshore lidar collection and processing system, and the resulting hourly data products are provided to the coastal community in real-time. The manuscript describes the original work in developing the set-up, collection, and processing algorithms for the lidar system. The high spatial and temporal resolution of the resulting data allows for analyses of beach evolution over a range of time scales, from seconds to years. In Chapter 3, data from the nearshore lidar system is applied in conjunction with continuous hydrodynamic data from the same site to analyze beach cusp development and evolution over a 21-month period. Cusp fields were found to form and evolve rapidly, often on the scale of individual tidal cycles. These formation events occurred primarily during low energy, long period swell conditions with narrow-banded frequency spread and reflective beach conditions. Results show that the generation of cusp fields on the lower beach were often influenced by cusp fields on the upper beach, with the upper beach cusp system exerting some control over the location and spacing of lower beach cusps. However, the presence of an upper beach cusp system alone was not sufficient to induce cusp formation on the lower beach. Chapters 4 and 5 utilize X-band radar remote sensing for rip current analysis. Current fields are visible in X-band radar images due to the interactions between short surface waves and the underlying currents, which result in changes in the roughness of the water surface and thus changes in radar backscatter intensity. In the fourth chapter, a surface roughness model is developed and compared to observations from Duck, NC (same field site as the lidar system). The roughness model utilizes rip current fields simulated using the nearshore circulation model ROMS. The modeled changes in surface roughness are compared to spatially- and temporally-overlapping X-band radar images. Results show that current-induced changes in surface roughness quantified through the change in the mean square slope of the water surface at gravity-capillary wavelengths are an effective proxy for current-induced changes in radar backscatter intensity. In the fifth chapter, X-band radar observations of transient and bathymetric rip currents are used as motivation for a modeling study focused on the conditions leading to transient rip activity on non-uniform beaches. A phase-resolving Boussinesq model (funwaveC) is used to simulate rip dynamics in a range of wave conditions on both a uniform and an alongshore varying bathymetry. The underlying bathymetry was found to strongly influence the alongshore- and time-averaged kinetic energy and exchange velocity. However, the transient exchange velocity calculated from the temporally-demeaned velocity field was similar across both bathymetric types. Instead, the largest differences in the transient exchange velocity were observed between simulations with and without directional spreading in the incident wave field. Directional spreading was also found to play an important role in alongshore- and time-averaged total and transient enstrophy. Alongshore vorticity wavenumber spectra show that the underlying bathymetry plays a large role in controlling surf zone vorticity at large spatial scales, but had no impact at smaller spatial scales, which were instead controlled by directional spread

Enhancing Multi-View 3D-Reconstruction Using Multi-Frame Super Resolution

Multi-view stereo is a popular method for 3D-reconstruction. Super resolution is a technique used to produce high resolution output from low resolution input. Since the quality of 3D-reconstruction is directly dependent on the input, a simple path is to improve the resolution of the input. In this dissertation, we explore the idea of using super resolution to improve 3D-reconstruction at the input stage of the multi-view stereo framework. In particular, we show that multi-view stereo when combined with multi-frame super resolution produces a more accurate 3D-reconstruction. The proposed method utilizes images with sub-pixel camera movements to produce high resolution output. This enhanced output is fed through the multi-view stereo pipeline to produce an improved 3D-model. As a performance test, the improved 3D-model is compared to similarly generated 3D-reconstructions using bicubic and single image super resolution at the input stage of the multi-view stereo framework. This is done by comparing the point clouds of the generated models to a reference model using the metrics: average, median, and max distance. The model that has the metrics that are closest to the reference model is considered to be the better model. The overall experimental results show that the generated models, using our technique, have point clouds with average mean, median, and max distances of 4.3\%, 8.8\%, and 6\% closer to the reference model, respectively. This indicates an improvement in 3D-reconstruction using our technique. In addition, our technique has a significant speed advantage over the single image super resolution analogs being at least 6.8x faster. The use of multi-frame super resolution in conjunction with the multi-view stereo framework is a practical solution for enhancing the quality of 3D-reconstruction and shows promising results over single image up-sampling techniques

Report on active and planned spacecraft and experiments

Information is presented, concerning active and planned spacecraft and experiments known to the National Space Science Data Center. The information included a wide range of disciplines: astronomy, earth sciences, meteorology, planetary sciences, aeronomy, particles and fields, solar physics, life sciences, and material sciences. These spacecraft projects represented the efforts and funding of individual countries as well as cooperative arrangements among different countries

A Fast NIR Spectrometer for Examining Explosive Events: Emission of PETN Based Explosives and H\u3csub\u3e2\u3c/sub\u3eO Absorption Method Feasibility

The chemical dynamics and decomposition pathways of explosive materials are not entirely known. Measurements of chemical transients during explosive events can lead to enhanced knowledge of the detailed chemistry and eventually control of the end products; however, these measurements are often difficult to obtain due to fast time scales and harsh environments. Optical diagnostics present fast-response, minimally invasive methods for resolving properties in detonation environments and previous fast spectroscopic measurements have been recorded in the ultra-violet and visible regions. This work extends the range of such measurements to the near-infrared (NIR) through the development of a fiber-coupled NIR spectrometer utilizing a fast InGaAs array. The characteristics and applications of this spectrometer are investigated through temporally and spectrally resolved measurements during the detonation and post-detonation combustion in arena-type explosives experiments. The spectrometer was used to examine the emission features and temperatures of atomic and molecular species with microsecond time resolution from pure pentaerythritol tetranitrate (PETN) charges and PETN charges doped with 10% (by mass) Ag and Al microparticles. The post-detonation spectra were observed between 750 nm and 1500 nm at rates up to 46k-spectra/sec, and key features were identified. Emission spectra from the particle doped charges followed a Planckian distribution at later times (\u3e40μs) and spectral pyrometry temperature measurements were determined from the spectra. The NIR spectrometer can also be used to acquire absorption spectra which can allow for the measurement of bulk gas temperature and direct species concentrations as well as provide more control over the probed volume. An investigation was conducted on the feasibility of using the newly developed NIR spectrometer in explosives experiments to measure water absorption in the 1330-1380 nm region and determine temperatures and concentrations of H2O using a fiber coupled broad light source. The fiber size, resolution, and path-length necessary for accurate temperature mol fraction H2O measurements were determined

Quantitative Automated Object Wave Restoration in High-Resolution Electron Microscopy

The main problem addressed by this dissertation is the accurate and automated determination of electron microscope imaging conditions. This enables the restoration of the object wave, which confers direct structural information about the specimen, from sets of differently aberrated images. An important member in the imaging chain is the image recording device, in many cases now a charge-coupled device (CCD) camera. Previous characterisations of these cameras often relied on the unjustified assumption that the Modulation Transfer Function (MTF) also correctly describes the spatial frequency dependent attenuation of the electron shot noise. A new theory is therefore presented that distinguishes between signal and noise transfer. This facilitates the evaluation of both properties using a detailed Monte-Carlo simulation model for the electron and photon scattering in the scintillator of the camera. Furthermore, methods for the accurate experimental determination of the signal and noise transfer functions are presented. In agreement with the Monte-Carlo simulations, experimental results for commercially available CCD cameras show that the signal transfer is significantly poorer than the noise transfer. The centrepiece of this dissertation is the development of new methods for determining the relative aberrations in a set of images and the absolute symmetric aberrations in the restored wave. Both are based on the analysis of the phase information in the Fourier domain and give each Fourier component a weight independent of its strength. This makes the method suitable even for largely crystalline samples with little amorphous contamination, where conventional methods, such as automated diffractogram fitting, usually fail. The method is then extended to also cover the antisymmetric aberrations, using combined beam tilt and focal series. The applicability of the new method is demonstrated with object wave restorations from tilt and focal series of complex inorganic block oxides and of carbon nanotubes filled with one-dimensional inorganic crystals. The latter specimens allowed for the first time a direct comparison between the phase shift in the restored object wave of a specimen with precisely known thickness and the value predicted by simulations