Hyper Redundancy for Accuracy Enhancement in Automated Close Range Photogrammetry

A generic network design in close range photogrammetry is one where optimal multi-ray intersection geometry is obtained with as few camera stations as practicable. Hyper redundancy is a concept whereby, once the generic network is in place, many additional images are recorded, with the beneficial impact upon object point precision being equivalent to the presence of multiple exposures at each camera position within the generic network. The effective number of images per station within a hyper redundant network might well be in the range of 10 to 20 or more. As is apparent when it is considered that a hyper redundant network may comprise hundreds of images, the concept is only applicable in practice to fully automatic vision metrology systems, where it proves to be a very effective means of enhancing measurement accuracy at the cost of minimal additional work in the image recording phase. This paper briefly reviews the network design and accuracy aspects of hyper redundancy and illustrates the technique by way of the photogrammetric measurement of surface deformation of a radio telescope of 26 m diameter. This project required an object point measurement accuracy of σ  = 0·065 mm, or 1/400 000 of the diameter of the reflector.     

Method of Data Reduction and Uncertainty Estimation for Platinum-Group Element Data Using Inductively Coupled Plasma-Mass Spectrometry

A data reduction method is described for determining platinum-group element (PGE) abundances by inductively coupled plasma-mass spectrometry (ICP-MS) using external calibration or the method of standard addition. Gravimetric measurement of volumes, the analysis of reference materials and the use of procedural blanks were all used to minimise systematic errors. Internal standards were used to correct for instrument drift. A linear least squares regression model was used to calculate concentrations from drift-corrected counts per second (cps). Furthermore, mathematical manipulations also contribute to the uncertainty estimates of a procedure. Typical uncertainty estimate calculations for ICP-MS data manipulations involve: (1) Carrying standard deviations from the raw cps through the data reduction or (2) calculating a standard deviation from multiple final concentration calculations. It is demonstrated that method 2 may underestimate the uncertainty estimate of the calculated data. Methods 1 and 2 do not typically include an uncertainty estimate component from a regression model. As such models contribute to the uncertainty estimates affecting the calculated data, an uncertainty estimate component from the regression must be included in any final error calculations. Confidence intervals are used to account for uncertainty estimates from the regression model. These confidence intervals are simpler to calculate than uncertainty estimates from method 1, for example. The data reduction and uncertainty estimation method described here addresses problems of reporting PGE data from an article in the literature and addresses both precision and accuracy. The method can be applied to any analytical technique where drift corrections or regression models are used.     

Height dependence of the amplitudes of solar oscillations viewed with a potassium resonance scattering spectrometer

Over the course of the year, the variation in the solar line-of-sight velocity causes a change in the heights in the photosphere which are analysed by the red and blue passbands of a resonance scattering spectrometer. This in turn would be expected to produce a variation in the ratio of acoustic amplitudes measured in each passband. Using data from the Tenerife spectrometer of the Birmingham Solar Oscillations Network (BiSON), we demonstrate such a seasonal change. We then use the Eddington-Barbier approximation and an atmospheric model to convert the magnitude of this trend in velocity ratio with line-of-sight velocity into an approximate value of 580 km for the velocity-amplitude scale height. However, a simple argument suggests that Doppler imaging causes this to be an overestimate of the true value.     

Gas kinematics in the halo of the warm ULIRG PKS1345+12

We use long-slit spectra taken with the William Herschel Telescope on La Palma and high-resolution Hubble Space Telescope imaging to study the gas kinematic in the halo of the ultraluminous infrared/radio galaxy PKS1345+12 (z=0.122). Our long-slit spectra show line splitting at the locations of massive star clusters ( $10^{6}<M_{\mathrm{SSC}}^{\mathrm{YSP}}<10^{7}$ M_⊙), indicating that they are moving at up to 450 km?s^?1 with respect to the local ambient gas. Given their kinematics, it is plausible that these super star clusters have been formed either in fast-moving gas streams or tidal tails that are falling back into the nuclear regions as part of the merger process, or as a consequence of jet-induced star formation linked to the extended, diffuse radio emission detected in the halo of the galaxy.     

Evidence for microbiological manganese oxidation in the river Tamar Estuary, South West England

Water samples from the Tamar Estuary oxidized manganese when supplemented with Mn²⁺ (2 mgl⁻¹). The rates of oxidation were depressed in the presence of various metabolic inhibitors. The effect of Mn²⁺ and temperature on the rate of manganese oxidation suggested that a biological process was largely responsible for converting Mn²⁺ to Mn⁴⁺. Rates of manganese oxidation were much higher in freshwater (3·32 μgl⁻¹ h⁻¹ in water containing 30 mgl⁻¹ of suspended matter) than in saline water (0·7 μgl⁻¹ h⁻¹ in water of salinity 32‰) containing the same amount of particulate matter. The rate of manganese oxidation was proportional to the particulate load (up to 100 mgl⁻¹ particulates).     

Sandy gravel accumulation in a fluvial environment

Particle size, pebble shape, pebble fabric, discharge and flow velocity data are used to introduce a model of sandy gravel formation in Welsh gravel-bed rivers. The development of contact-imbrication of the typically very bladed and very platy cobbles and larger pebbles subsequently acts to significantly affect the depositional modes and patterns of small pebbles and sand particles. An important distinction is drawn between sand deposition, which can occur at or below the bed surface, and pebble and cobble deposition, which is merely a surface phenomenon.     

Volcanoes of the Tibesti massif (Chad,northern Africa)

The Tibesti massif, one of the most prominent features of the Sahara desert, covers an area of some 100,000 km². Though largely absent from scientific inquiry for several decades, it is one of the world’s major volcanic provinces, and a key example of continental hot spot volcanism. The intense activity of the TVP began as early as the Oligocene, though the major products that mark its surface date from Lower Miocene to Quaternary (Furon (Geology of Africa. Oliver & Boyd, Edinburgh (trans 1963, orig French 1960), pp 1–377, 1963)); Gourgaud and Vincent (J Volcanol Geotherm Res 129:261–290, 2004). We present here a new and consistent analysis of each of the main components of the Tibesti Volcanic Province (TVP), based on examination of multispectral imagery and digital elevation data acquired from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Our synthesis of these individual surveys shows that the TVP is made up of several shield volcanoes (up to 80 km diameter) with large-scale calderas, extensive lava plateaux and flow fields, widespread tephra deposits, and a highly varied structural relief. We compare morphometric characteristics of the major TVP structures with other hot spot volcanoes (the Hawaiian Islands, the Galápagos Islands, the Canary and Cape Verdes archipelagos, Jebel Marra (western Sudan), and Martian volcanoes), and consider the implications of differing tectonic setting (continental versus oceanic), the thickness and velocity of the lithosphere, the relative sizes of main volcanic features (e.g. summit calderas, steep slopes at summit regions), and the extent and diversity of volcanic features. These comparisons reveal morphologic similarities between volcanism in the Tibesti, the Galápagos, and Western Sudan but also some distinct features of the TVP. Additionally, we find that a relatively haphazard spatial development of the TVP has occurred, with volcanism initially appearing in the Central TVP and subsequently migrating to both the Eastern and Western TVP regions. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Quality Assessment Of Digital Surface Models Generated From IKONOS Imagery

The growing applications of digital surface models (DSMs) for object detection, segmentation and representation of terrestrial landscapes have provided impetus for further automation of 3D spatial information extraction processes. While new technologies such as lidar are available for almost instant DSM generation, the use of stereoscopic high-resolution satellite imagery (HRSI), coupled with image matching, affords cost-effective measurement of surface topography over large coverage areas. This investigation explores the potential of IKONOS Geo stereo imagery for producing DSMs using an alternative sensor orientation model, namely bias-corrected rational polynomial coefficients (RPCs), and a hybrid image-matching algorithm. To serve both as a reference surface and a basis for comparison, a lidar DSM was employed in the Hobart testfield, a region of differing terrain types and slope. In order to take topographic variation within the modelled surface into account, the lidar strip was divided into separate sub-areas representing differing land cover types. It is shown that over topographically diverse areas, heighting accuracy to better than 3 pixels can be readily achieved. Results improve markedly in feature-rich open and relatively flat terrain, with sub-pixel accuracy being achieved at check points surveyed using the global positioning system (GPS). This assessment demonstrates that the outlook for DSM generation from HRSI is very promising.