High-resolution Height Research Articles

Orthorectification of Bridges from High Resolution Satellite Images

Abstract. High-resolution satellite imagery requires high-resolution height reference data to create orthorectified images. High-precision digital surface data and LiDAR data are expensive to acquire quickly and accurately. Facility databases, on the other hand, are very efficient because once established, the information can be utilized persistently. The temporal resolution between the structure in the database and the captured image affects the ortho resolution created. Landmarks such as bridges are rarely subject to changes after construction. This makes facility database a suitable material to generate orthophotos of bridge structures. In this paper, we used a bridge database to perform orthorectification for structures with height variations. We removed relief displacement from satellite imagery at different angles and verified orthorectification feasibility for bridges of different heights and lengths. The orthoimage was overlaid with a topographic map to verify the orthorectification visually. As a result, we confirmed that the facility database was able to generate orthophotos of the bridges. The length and slope of bridge structures indicated the need for precise database updates in the future research.

Multiscale mapping of local climate zones in Tokyo using airborne LiDAR data, GIS vectors, and Sentinel-2 imagery

ABSTRACT Multisource remote sensing and geographic information system (GIS) data have contributed powerfully to the large-scale automated mapping of local climate zones (LCZs). However, the accessibility of high-resolution height data, the applicability of standard thresholds to local contexts, and the dependence of mapping scales have limited LCZ classification studies. In this study, we combined airborne LiDAR data, Sentinel-2 imagery, and GIS vector (buildings and roads) data to develop a multiscale automated LCZ classification scheme in the 23 special wards of Tokyo. Based on the optimized thresholds of seven LCZ properties, GIS-based LCZ mapping was implemented using fuzzy logic classifiers at the block scale and at different grid-cell scales (100 m–1000 m). In addition to assessing accuracy using reference samples, multidate thermal infrared data (Landsat-8 and ASTER data) were used to understand the LCZ-LST (land surface temperature) relationship at multiple scales. The results showed that the overall accuracies of LCZs could be significantly increased by threshold optimization at all scales. Significant differences in LCZs and LSTs among different mapping units were observed. The highest overall accuracy was greater than 80% at the 100-m grid-cell scale. As the size of grid cells increased, the overall accuracy of LCZ classification decreased. For each LCZ, the mean daytime/nighttime LST exhibited more variation by date than by scale. This study provides a promising picture of GIS-based LCZ mapping and LCZ-LST relationships at multiple scales.

Example-Based Microstructure Rendering with Constant Storage

Rendering glinty details from specular microstructure enhances the level of realism, but previous methods require heavy storage for the high-resolution height field or normal map and associated acceleration structures. In this article, we aim at dynamically generating theoretically infinite microstructure, preventing obvious tiling artifacts, while achieving constant storage cost. Unlike traditional texture synthesis, our method supports arbitrary point and range queries, and is essentially generating the microstructure implicitly. Our method fits the widely used microfacet rendering framework with multiple importance sampling (MIS), replacing the commonly used microfacet normal distribution functions (NDFs) like ground glass distribution (GGX) by a detailed local solution, with a small amount of runtime performance overhead.

Generation of photoclinometric DTMs for application to transient changes on the surface of comet 67P/Churyumov-Gerasimenko

Context. The wide spatial and temporal coverage of 67P/Churyumov-Gerasimenko (67P) by the Rosetta mission has revealed a surface created by scattered large-scale changes and numerous small-scale changes. The many small-scale changes are of particular interest because they are unexpected and ubiquitous. As their topographic relief is often smaller than one meter, which is below the resolution of any shape models, we need higher resolution topography to analyze them properly. Aims. We describe a photoclinometry method that is able to retrieve surface elevations for a single OSIRIS image of the surface of 67P. With this method, we can provide accurate measures, along with error estimates, of the centimeter-scale topography of observed transient changes. Methods. Photoclinometry, or shape-from-shading, estimates heights by examining the light reflection of the surface as dictated by a photometric model under a specified set of viewing geometries. Assuming a standard photometric model for 67P, we can recreate the shading of a surface under specified viewing geometries. The output is a high-resolution height map that matches the original image pixel by pixel. We then provide estimates of the error in the retrieved heights and ensure that our method is valid with a series of checks. Results. We generate digital terrain models (DTMs) with a vertical resolution comparable to or smaller than the pixel scale. This allows us to accurately measure changes in the surface topography on centimeter scales. We find that most changes within the smooth terrains involve the transport or removal of material thinner than one meter.

Spatial Distribution Estimates of the Urban Population Using DSM and DEM Data in China

Spatial distribution and population density are important parameters in studies on urban development, resource allocation, emergency management, and risk analysis. High-resolution height data can be used to estimate the total or spatial pattern of the urban population for small study areas, e.g., the downtown area of a city or a community. However, there has been no case of population estimation for large areas. This paper tries to estimate the urban population of prefectural cities in China using building height data. Building height in urban population settlement (Mdiffs) was first extracted using the digital surface model (DSM), digital elevation model (DEM), and land use data. Then, the relationships between the census-based urban population density (CPD) and the Mdiffs density (MDD) for different regions were regressed. Using these results, the urban population for prefectural cities of China was finally estimated. The results showed that a good linear correlation was found between Mdiffs and the census data in each type of region, as all the adjusted R2 values were above 0.9 and all the models passed the significance test (95% confidence level). The ratio of the estimated population to the census population (PER) was between 0.7 and 1.3 for 76% of the cities in China. This is the first attempt to estimate the urban population using building height data for prefectural cities in China. This method produced reasonable results and can be effectively used for spatial distribution estimates of the urban population in large scale areas.

LiDAR Data Filtering and DTM Generation Using Empirical Mode Decomposition

LiDAR technology is advancing. As a result, researchers can benefit from high-resolution height data from Earth’s surface. Digital terrain model (DTM) generation and point classification (filtering) are two important problems for LiDAR data. These are connected problems since solving one helps solving the other. Manual classification of LiDAR point data could be time consuming and prone to errors. Hence, it would not be feasible. Therefore, researchers proposed several methods to solve DTM generation and point classification problems. Although these methods work fairly well in most cases, they may not be effective for all scenarios. To contribute in this research topic, a novel method based on two-dimensional (2-D) empirical mode decomposition (EMD) is proposed in this study. Local, nonlinear, and nonstationary characteristics of EMD allow better DTM generation. The proposed method is tested on two publicly available LiDAR dataset, and promising results are obtained. Besides, the proposed method is compared with other methods in the literature. Comparison results indicate that the proposed method has certain advantages in terms of performance.

Generation and Dissemination of a National Virtual 3D City and Landscape Model for the Netherlands

This paper describes the generation and dissemination of a national three-dimensional (3D) dataset representing the virtual and landscape model. The 3D model is produced automatically by fusing a two-dimensional (2D) national objectoriented database describing the physical landscape and the national high-resolution height model of the Netherlands. Semantic constraints are introduced to correctly model 3D objects. Three areas from different regions in the Netherlands have been processed in order to develop, improve, and test the automatic generation of a national 3D city and landscape model. Specific attention has been paid to exceptional cases that may occur in a nationwide dataset. Based on the test results, the Kadaster, the national agency in the Netherlands responsible for the production of nation wide geo-information, decided that it is feasible to produce a national 3D city and landscape model that fulfills the specifications that were defined as part of this study. Future research is identified to make the results further ready for practice.

High resolution 3-dimensional documentation of archaeological monuments & landscapes using airborne LiDAR

Over the past 16 years, the Discovery Programme, an Irish archaeological research organisation, has strived to produce accurate high resolution 3-dimensional models of earthwork monuments and their archaeological landscapes. Initially, this was achieved by the use of terrestrial-based survey technologies including total stations and RTK GPS. However, this is a slow, labour intensive way to build such models, and often the final archaeological models were devoid of their landscape context. In 2003, the Discovery Programme implemented, to great effect, the use of digital aerial stereo photogrammetry in the creation of landscape and monument 3-dimensional models and associated orthoimages. However, problems including the occlusion of features due to vegetation cover, and the great effort and expertise needed to process the data were evident. Since the development of fixed wing Light Detection and Ranging (LiDAR), and its ability to rapidly produce landscapes Digital Terrain Models (DTM) even beneath vegetation, the Discovery Programme has monitored its application to the recording of archaeological features. Although impressive results have been seen from many examples of landscape modelling, the resolution and accuracy of the sensor devices (0.5m and 15 cm respectively) often falls short to effectively record the subtle details and relationships of complex archaeological features. Since 2007, the Discovery Programme has employed the use of a new aerial LiDAR system: FLI-MAP 400 from BKS Surveys Ltd. (UK) and Fugaro Ltd. (Netherlands). This technology has the advantage in that it is helicopter mounted, allowing for relatively slow air speeds and low altitude flight paths which result in the collection of extremely high resolution height data (10 cm). The FLI-MAP 400 system is equipped with three 150 Khz laser scanners (forward – nadir – aft), that have a range accuracy of 1 cm (1 sigma) and several imaging devices including high resolution mapping camera and three video cameras accompanying each laser scanner. This technology has been successfully implemented on three archaeological sites: Newtown Jerpoint abandoned medieval settlement, Dún Ailinne prehistoric hillfort and the Hill of Tara archaeological complex. This paper illustrates the results of these surveys, and the high level of terrain and monument detail recorded. Discussion includes the processing required to produce the final models and the level of vegetation removal that can be achieved from the multiple return signals of the LiDAR pulse. Examples are employed where the resulting terrain models are interpreted with additional field inspection to further the understanding of the archaeological features and structures. Subsequent interpretations are then used in conjunction with the high resolution models to enable the realistic visualisation of monument and landscape features. Finally, there is an evaluation of this methodology against alternative LiDAR and ground-based approaches.

The effects of fluoride on the nanostructure and surface pK of enamel crystals: an atomic force microscopy study of human and rat enamel

Atomic force microscopy (AFM) studies have revealed 30-40 nm-wide regular positively charged bands across maturation-stage rat enamel crystals. Low pH resolved these into positively charged spherical domains of approximately 30 nm diameter. Crystal surface pK values from adhesion force titrations were approximately 6.5. The effect of fluoride on this pK value and on the nanostructure of fluorosed human enamel crystals has not been reported. The nanostructure and surface chemistry (pK) of normal and fluorotic human and of fluoride-treated rat maturing enamel crystals was examined. Enamel was sectioned and polished, prior to examination, using AFM in height and friction modes. High-resolution height images revealed 30 nm-diameter spherical domains within crystals, arranged as layers of hexagons or as a shallow spiral. Fluorotic enamel showed similar, but less well ordered, nanodomains. These could represent an arrangement of original initiation sites or binding sites for modulating matrix proteins. Surface pK was derived from adhesion-force measurements between functionalized tips (OH or COOH) and crystal surfaces between pH 2 and pH 10. pK values of approximately 6.5 for normal crystals were reduced to approximately 5.5 after fluoride treatment. Reduction in surface pK by fluoride might indicate lowered protonation with possible effects on matrix protein binding.

A study on high‐resolution target height estimation in multipath environment—subarray configuration

AbstractIt is well known that a large spike error and a bias error occur in the monopulse angle measurement process (of height estimation due to sea surface reflection or road surface reflection) when height estimation of a low‐altitude target is carried out with an air traffic control radar or a tracking radar with a monopulse antenna. In this paper, a target height estimation method is proposed that can seek the estimation object with only one parameter of the target height, even if fading prevention by frequency hopping and a subarray configuration of the array antenna based on the maximum likelihood estimation method is used. By means of computer simulation, the S/N dependence and equivalent earth radius error dependence of the target height estimation error are evaluated when the conventional ΣΔ monopulse method, the maximum likelihood estimation method without frequency hopping for four subarrays, and the proposed maximum likelihood estimation method with frequency hopping are used. Even though the evaluation is within the limited conditions, it is confirmed that the proposed method can estimate the target height while fading prevention is attempted in a multipath environment. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(11): 39–48, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10208

Simultaneous Height and Adhesion Imaging of Antibody-Antigen Interactions by Atomic Force Microscopy

Specific molecular recognition events, detected by atomic force microscopy (AFM), so far lack the detailed topographical information that is usually observed in AFM. We have modified our AFM such that, in combination with a recently developed method to measure antibody-antigen recognition on the single molecular level (Hinterdorfer, P., W. Baumgartner, H. J. Gruber, K. Schilcher, and H. Schindler, Proc. Natl. Acad. Sci. USA 93:3477–3481 (1996)), it allows imaging of a submonolayer of intercellular adhesion molecule-1 (ICAM-1) in adhesion mode. We demonstrate that for the first time the resolution of the topographical image in adhesion mode is only limited by tip convolution and thus comparable to tapping mode images. This is demonstrated by imaging of individual ICAM-1 antigens in both the tapping mode and the adhesion mode. The contrast in the adhesion image that was measured simultaneously with the topography is caused by recognition between individual antibody-antigen pairs. By comparing the high-resolution height image with the adhesion image, it is possible to show that specific molecular recognition is highly correlated with topography. The stability of the improved microscope enabled imaging with forces as low as 100 pN and ultrafast scan speed of 22 force curves per second. The analysis of force curves showed that reproducible unbinding events on subsequent scan lines could be measured.

Precise geoid determination using a density variation model

The contribution of a density variation model in combination with a high resolution height model for the precise determination of the Austrian gravimetric geoid is investigated. Numerical results are given for a test area of 2° × 2° in the central part of Austria. The computation follows the well known remove-restore process. Within this process RTM-method (RTM is the abbreviation for residual terrain model) is used to subtract the short wavelength part of the gravity field. Stokes integral is evaluated by FFT-techniques. Additionally the quality of the new released geopotential model EGM96 for the approximation of the long wavelengths of the Austrian gravity field is tested. The numerical tests show that even small changes in the density values can effect the gravimetric geoid by more than 10 cm.

Sub-pixel Bayesian estimation of albedo and height

Given a set of low resolution camera images of a Lambertian surface, it is possible to reconstruct high resolution luminance and height information, when the relative displacements of the image frames are known. We have proposed iterative algorithms for recovering high resolution albedo with the knowledge of high resolution height and vice versa. The problem of surface reconstruction has been tackled in a Bayesian framework and has been formulated as one of minimizing an error function. Markov Random Fields (MRF) have been employed to characterize the a priori constraints on the solution space. As for the surface height, we have attempted a direct computation without refering to surface orientations, while increasing the resolution by camera jittering.

Reactive Dimerization: A New PAH Growth Mechanism in Flames

ABSTRACT The formation of polycyclic aromatic hydrocarbon (PAH) molecules in laminar diffusion flames is investigated by time-of-flight mass spectrometry combined with laser two-photon ionization. Gas samples from the flames are analyzed on-line with the help of a new inlet system that permits the recording of high-resolution height profiles. Such curves from 13 different flame species of pure and Ar-, C02- or H2- diluted methane flames were measured. Larger PAH are generally found higher in the flame than smaller ones. This behaviour is described by a simple model for successive growth. Some PAH however deviate from this trend and are formed faster than their precursors. This is inconsistent with successive growth and suggests the occurrence of growth by reactive coagulation.

New aspects of growth mechanisms for polycyclic aromatic hydrocarbons in diffusion flames

Two-photon ionization time-of-flight mass spectroscopy is used to analyze combustion products from laminar methane diffusion flames. High-resolution height profiles in the symmetry axis of the flame show sensitively the rise and decay of concentrations of various polycyclic aromatic hydrocarbons (PAH) in the mass range up to 472 amu. From a comparison of these profiles in dependence of the carbon content of the PAH, we derive fingerprints both of successive acetylene addition and of reactive coagulation as growth mechanisms of PAH.

Scanning farfield and scanning nearfield probe microscopy of catalase platelets

High resolution (sub nm) and direct height information obtained through scanning probe microscopy (SPM) (such as from the STM and AFM) establishes SPM as a valuable tool for the investigation of biological samples. Unfortunately SPM allows only regions of a few μm to be scanned at high speed. For biological applications this is a disadvantage, because most samples will be only of the μm size and scattered across the much larger substrate. To make SPM investigation of biological samples less tedious, we combined a STM (or alternatively an AFM) with an inverted confocal scanning laser microscope (CSLM), with a lateral and axial resolution of 200 nm and 400 nm, respectively. This enables to locate areas of interest on the substrate and position the tip of the STM. STM tips used are electro-chemically etched from Au to routinely attain tip radii in the 5 nm range. Catalase platelets were chosen as a sample, because of their established two different lattice repeats (17.5 nm and 6.8 nm).

Airborne Radar Altimeter Measurements of Geostrophic and Ageostrophic Winds Over Irregular Topography

Abstract Radar altimeter and inertial wind velocity measurements from the NCAR Sabreliner research aircraft are combined with Defense Mapping Agency high-resolution (∼1 km) digital terrain height maps to obtain height analyses and geostrophic and ageostrophic winds for upper-level jet stream systems situated over land. Results show that given an accurate geographical location of the aircraft over an accurately mapped topography, it is possible to diagnose geostrophically and convectively forced ageostrophic motions over irregular topography.

High resolution measurements of space radiation effects on silicon surface-barrier detectors

Two high-resolution charged particle spectrometers employing silicon surface-barrier detectors have been operated in an 800 km altitude polar orbit for a 26-month period between October 1971 and December 1973-Based on existing trapped radiation models and the measured solar flare environment during this period the detectors were exposed to a proton fluence of 2.8 t 1013 protons/cm2 at energies > 400 keV and an electron fluence of 4.5 t 1013 electrons/cm2 at energies > 50 keV. High-resolution pulse height spectra of the alpha particles from low-intensity Americium-241 in-flight calibration sources show that the resolutions of the detectors did not degrade more than 5 percent and that the gains of the system did not vary more than 1.2 percent as a result of this exposure. Two aspects of detector operation are considered responsible for this performance. First, the incident detectors were operated with the rear, aluminum contact exposed to the radiation environment instead of the front, gold contact. The more intense lower energy radiation is therefore stopped in the rear ohmic contact region instead of in the front surface-barrier junction region and the overall damage effects are significantly reduced. Second, a detector bias technique was employed that automatically maintained a constant depletion potential across the detector independent of variations in leakage current due to radiation damage.

On-Line Data Collection by Computer in a Multi-Experiment Biomedical Gamma Spectroscopy System

A system is described in which a PDP-8 computer collects data on-line from up to twenty high-resolution pulse height analyzers used in biomedical gamma spectroscopy counting. The computer takes data directly from the analog-to-digital converters and stores it unsorted on IBM magnetic tape. These tapes are sorted and analyzed off-line on larger computers. An oscilloscope provides two modes of display of the spectral data being collected. Through another interface, the PDP-8 accepts complete spectra dumped from the memories of other analyzers operating off-line.