CODE’s new ultra-rapid orbit and ERP products for the IGS

The International GNSS Service (IGS) issues four sets of so-called ultra-rapid products per day, which are based on the contributions of the IGS Analysis Centers. The traditional (“old”) ultra-rapid orbit and earth rotation parameters (ERP) solution of the Center for Orbit Determination in Europe (CODE) was based on the output of three consecutive 3-day long-arc rapid solutions. Information from the IERS Bulletin A was required to generate the predicted part of the old CODE ultra-rapid product. The current (“new”) product, activated in November 2013, is based on the output of exactly one multi-day solution. A priori information from the IERS Bulletin A is no longer required for generating and predicting the orbits and ERPs. This article discusses the transition from the old to the new CODE ultra-rapid orbit and ERP products and the associated improvement in reliability and performance. All solutions used in this article were generated with the development version of the Bernese GNSS Software. The package was slightly extended to meet the needs of the new CODE ultra-rapid generation.     

A COM-based Framework for Management, Analysis and Visualization of Large Scope Digital Elevation Models

This paper presents a component object model (COM) based framework for managing, analyzing and visualizing massive multi-scale digital elevation models (DEMs). The framework consists of a data manage-ment component (DMC), which is based on RDBMS/ORDBMS, a data a-nalysis component (DAC) and a data render component (DRC). DMC can manage massive multi-scale data ex-pressed at various reference frames within a pyramid database and can support fast access to data at variable resolution. DAC integrates many use-ful applied analytic functions whose re-sults can be overlaid with the 3D scene rendered by DRC. DRC provides view-dependent data paging with the sup-port of the underlying DMC and or-ganizes the potential visible data at dif-ferent levels into rendering.     

Geospatial Technologies for National Geomorphology and Lineament Mapping Project – A Case Study of Goa State

A three level classification system, based on the genesis of landforms, was used to map the geomorphology of the Goa state. The first level corresponds to the process that was responsible for landform generation, the second level or the intermediate level was assigned based on the morphography, and the third level corresponds to the individual landforms units identified based on the morphostructure. The mapping was carried out using IRS-P6 LISS-III (23.5 m) satellite image as the primary data source. Ancillary data such as geological map, topographic map, digital elevation model (DEM), field data collected by global positioning system (GPS) and web portals for image visualisation, were also used for the mapping purpose. A new software designed for mapping landforms based on the genesis, was used in this study to create a seamless geomorphology and lineament database of the Goa state in a GIS environment. A total of 58 landforms within six types of genetic classes were mapped in this area. Similarly, structural and geomorphic lineaments were also delineated using the satellite data. The database created has multi-purpose usability such as environmental studies, mining activity assessment, coastal zone management and wasteland development, since the classification system used is focused on processes, not theme specific.     

Cartography-Oriented Design of 3D Geospatial Information Visualization – Overview and Techniques

In economy, society and personal life map-based interactive geospatial visualization becomes a natural element of a growing number of applications and systems. The visualization of 3D geospatial information, however, raises the question how to represent the information in an effective way. Considerable research has been done in technology-driven directions in the fields of cartography and computer graphics (e.g., design principles, visualization techniques). Here, non-photorealistic rendering (NPR) represents a promising visualization category – situated between both fields – that offers a large number of degrees for the cartography-oriented visual design of complex 2D and 3D geospatial information for a given application context. Still today, however, specifications and techniques for mapping cartographic design principles to the state-of-the-art rendering pipeline of 3D computer graphics remain to be explored. This paper revisits cartographic design principles for 3D geospatial visualization and introduces an extended 3D semiotic model that complies with the general, interactive visualization pipeline. Based on this model, we propose NPR techniques to interactively synthesize cartographic renditions of basic feature types, such as terrain, water, and buildings. In particular, it includes a novel iconification concept to seamlessly interpolate between photorealistic and cartographic representations of 3D landmarks. Our work concludes with a discussion of open challenges in this field of research, including topics, such as user interaction and evaluation.     

Evaluation of Goddard’s LiDAR,hyperspectral, and thermal data products for mapping urban land-cover types

Goddard’s LiDAR (Light Detection And Ranging), hyperspectral and thermal (G-LiHT) airborne imager is a new system to advance concepts of data fusion for worldwide applications. A recent G-LiHT mission conducted in June 2016 over an urban area opens a new opportunity to assess the G-LiHT products for urban land-cover mapping. In this study, the G-LiHT hyperspectral and LiDAR-canopy height model (LiDAR-CHM) products were evaluated to map five broad land-cover types. A feature/decision-level fusion strategy was developed to integrate two products. Contemporary data processing techniques were applied, including object-based image analysis, machine-learning algorithms, and ensemble analysis. Evaluation focused on the capability of G-LiHT hyperspectral products compared with multispectral data with similar spatial resolution, the contribution of LiDAR-CHM, and the potential of ensemble analysis in land-cover mapping. The results showed that there was no significant difference between the application of the G-LiHT hyperspectral product and simulated Quickbird data in the classification. A synthesis of G-LiHT hyperspectral and LiDAR-CHM products achieved the best result with an overall accuracy of 96.3% and a Kappa value of 0.95 when ensemble analysis was applied. Ensemble analysis of the three classifiers not only increased the classification accuracy but also generated an uncertainty map to show regions with a robust classification as well as areas where classification errors were most likely to occur. Ensemble analysis is a promising tool for land-cover classification.     

The optimal Mercator projection and the optimal polycylindric projection of conformal type – case-study Indonesia

As a conformal mapping of the sphere S ² _R or of the ellipsoid of revolution E ² _A , _B the Mercator projection maps the equator equidistantly while the transverse Mercator projection maps the transverse metaequator, the meridian of reference, with equidistance. Accordingly, the Mercator projection is very well suited to geographic regions which extend east-west along the equator; in contrast, the transverse Mercator projection is appropriate for those regions which have a south-north extension. Like the optimal transverse Mercator projection known as the Universal Transverse Mercator Projection (UTM), which maps the meridian of reference Λ₀ with an optimal dilatation factor &ρcirc;=0.999 578 with respect to the World Geodetic Reference System WGS 84 and a strip [Λ₀−Λ _W ,Λ₀ + Λ _E ]×[Φ _S ,Φ _N ]= [−3.5^∘,+3.5^∘]×[−80^∘,+84^∘], we construct an optimal dilatation factor ρ for the optimal Mercator projection, summarized as the Universal Mercator Projection (UM), and an optimal dilatation factor ρ₀ for the optimal polycylindric projection for various strip widths which maps parallel circles Φ₀ equidistantly except for a dilatation factor ρ₀, summarized as the Universal Polycylindric Projection (UPC). It turns out that the optimal dilatation factors are independent of the longitudinal extension of the strip and depend only on the latitude Φ₀ of the parallel circle of reference and the southern and northern extension, namely the latitudes Φ _S and Φ _N , of the strip. For instance, for a strip [Φ _S ,Φ _N ]= [−1.5^∘,+1.5^∘] along the equator Φ₀=0, the optimal Mercator projection with respect to WGS 84 is characterized by an optimal dilatation factor &ρcirc;=0.999 887 (strip width 3^∘). For other strip widths and different choices of the parallel circle of reference Φ₀, precise optimal dilatation factors are given. Finally the UPC for the geographic region of Indonesia is presented as an example. Received: 17 December 1997 / Accepted: 15 August 1997     

The dynamics in the distribution of mangrove forests in Pichavaram,South India – perception by user community and remote sensing

This study aims to monitor the forest cover of Pichavaram mangroves, South India over a period of 40 years using remote sensing, and to record the status of mangroves as perceived by the local community. Out of 1471 ha of total reserved forest area, mangroves occupy 906 ha. The remote sensing maps show that there was a loss of 471 ha from 1970 to 1991 and a gain of 531 ha in 2011. Nearby 20 hamlets depend on mangroves for their livelihood. A village survey conducted at Pichavaram shows that more than 90% of the local community is well aware of the prevailing species, their importance especially after the 2004 tsunami and the impact of management practices, increased rainfall and contribution of local community in the recent increased area of mangroves. The same can be noticed from the high-resolution IKONOS image showing the artificial canal network in the restored region and from rainfall records.     

Achieving the Impossible: The 1∶500 000 ‘Irrigation Map’ of South Africa, 1935–1937

Abstract

Since 1906, South Africa boasted an excellent geodetic framework, and in 1920 an official Trigonometrical Survey Office (TSO) was established. In spite of these achievements, the country, by the 1930s, still lacked reliable topographical maps. One reason for this was that the secondary and tertiary triangulations of the country were still incomplete; another was that the decision-making process as regards surveys and mapping rested with a variety of statutory bodies instead of just one. In 1934, A. D. Lewis, Director of the Department of Irrigation, committed his department to execute a general topographical survey of the country and produce a topographical map on a scale of 1∶500?000. Lewis’ decision met with much resistance from within the country and abroad, but the project was completed in a record period of 4 years. Published just before the Second World War, the map was of inestimable value to the South African Defense Force. It not only became the standard topographical map of large parts of South Africa for many years, but its contents also figured in the first map series of the TSO.     

The First Depiction of Two Superimposed Geographical Surfaces in One Autostereoscopic Map: Antarctica’s Topography and the Southern Ocean Seafloor

Within the past 10–15 years true-3D lenticular cartography has experienced a remarkable boost. In the course of this development, besides studies into its potential for thematic-cartographic representations, the synoptic depiction of physical surfaces (‘geo[graphical] surfaces’) has been playing a significant role. In this context the innovative holistic display of complex morphological and topographical conditions is of particular interest. The simultaneous representation of various cartographic parameters at different depths will deliver an enormous surplus of information transfer in the field of thematic cartography as well as in physical/topographic cartography. This paper describes the methodological development and generation of an autostereoscopic hardcopy display of Antarctic topography. The purpose was the simultaneous depiction of the two superimposed surfaces of both the ice-sheet and the rock-bed and, in addition, of the surrounding seafloor, thus displaying a vertical drop of more than 12,000?m.     

Space Rockets, Polar Bears, and Tundra Buggies – And a GPS Link to the Seventeenth Century

The use of the Global Positioning System (GPS) for position and attitude determination has been exploited for many years. In these systems, it was required that multiple antennas maintained phase lock to common view satellites for long periods of time in order to determine integer ambiguities. The challenge to overcome with the ballistic space probe is the high rotational spin of this particular rocket. The antennas, mounted on the outside skin of the rocket, are in full view of each satellite only for a fraction of a second before the rocket core eclipses them as it rotates. The antennas rarely see common satellites. This article describes as system that overcomes these obstacles and provides position, acceleration, attitude, and rotation rate. The approach uses a two-antenna system. One antenna is mounted either side of the rocket facing out. A hybrid tracking channel combines signals from both antennas to overcome the signal blockage due to the rocket core as well as to defeat the effect on the tracking channel due to the spin. The amplitude and phase of the spin rotation signature from each satellite is extracted from the dual antenna data and used to compute the attitude and spin rate of the vehicle. ? 1999 John Wiley & Sons, Inc.     

The scheme for the database building and updating of 1∶10 000 digital elevation models

［1］Balce A E. Determination of optimum sampling interval in grid digital elevation models (DEM) data acquisition.Photogrammetric Engineering and Remote Sensing,1987,531:323～330 ［2］Li Z L. Sampling strategy and accuracy assessment for digital terrain modelling: [Ph. D Thesis]. UK: University of Glasgow, 1990 ［3］Li Z L. Variation of the accuracy of digital terrain models with sampling interval. Photogrammetric Record, 1992,14:113～128 ［4］Li Z L. A comparative study of the accuracy of digital terrain models(DTMs) based on various data models. ISPRS Journal of Photogrammetry and Renote Sensing,1994,49(1):2～11 ［5］Li Z L. Scale issues in geographic information science. In:Proceeding of International Workshop on Dynamic and Multi-dimensional GIS. Hong Kong, 1997. 143～158 ［6］SISM. Specification of geospatial data (Provisional) for 1:10 000 digital elevation models. The Standard Institute of Surveying and Mapping (SISM), National Bureau of Surveying and Mapping, China, 1997(in Chinese) ［7］USGS. National Mapping Program: Geospatial Data Standard, 1992 ［8］Zhu Q, Cheng C J. The fast generation and dynamic updating of TIN. Journal of Wuhan Technical University of Surveying and Mapping, 1998(in Chinese)     

The scheme for the database building and updating of 1∶10 000 digital elevation models

The National Bureau of Surveying and Mapping of China has planned to speed up the development of spatial data infrastructure (SDI) in the coming few years. This SDI consists of four types of digital products, i. e., digital orthophotos, digital elevation models, digital line graphs and digital raster graphs. For the DEM, a scheme for the database building and updating of 1∶10 000 digital elevation models has been proposed and some experimental tests have also been accomplished. This paper describes the theoretical (and/or technical) background and reports some of the experimental results to support the scheme. Various aspects of the scheme such as accuracy, data sources, data sampling spatial resolution, terrain modeling, data organization, etc are discussed.     

The Palestine Exploration Fund Map (1871–1877) of the Holy Land as a Tool for Analysing Landscape Changes: the Coastal Dunes of Israel as a Case Study

Abstract

The Palestine Exploration Fund (PEF) maps (1871–1877) are highly praised for their accuracy and completeness; however, no systematic analysis of their accuracy has been done to date. To study the potential of these 1:63,360 maps for a quantitative analysis of land cover changes over a period of time, I have compared them to 20th century topographic maps. The map registration error of the PEF maps was 74.4 m using 123 control points of trigonometrical stations and a 1st order polynomial. The median RMSE of all control and test points (n = 1104) was 153.6 m. As a case study of land cover changes, the area of coastal dunes as shown on the PEF maps was compared with that shown on British Mandate 1:20,000 topo-cadastral maps from c. 1930. In five of the six areas analysed, the yearly dunes movement rate was above the estimated annual error due to data resolution (2.96 m/year). The rate of dune movement south of Acre was found to be between 3.9 and 6.3 m/year (depending on the method used for map registration) between 1874 and 1930. Care should be taken when analysing historical maps, as it cannot be assumed that their accuracy is consistent at different parts or for different features depicted on them.     

The application of remote sensing data to diagnose soil degradation in the Dakhla depression – Western Desert,Egypt

Dakhla depression in Egypt’s Western Desert is experiencing two soil degradation processes, notably: soil salinization and sand encroachment. The present study aimed to diagnose the severity of these processes using remote sensing. Soil salinity was determined by spectral regression analysis between tasselled cap spectral transform extracted from a Landsat-8 image acquired in September 2013 along with synchronized soil salinity measurements. Assessment of sand advance rate was conducted by temporal change detection of brilliant crescentic sand dune visualized by Google Earth in old (2002) and recent (2013) images. Results showed that salinized soils (dS/m4<) represent 91% of bare lands and salinization is attributed to aridity, topography and poor drainage. Barchan dunes north and south of Abu Tartur escarpment moved at rates of 5.9 and 3.6 m/year, respectively. The escarpment protected the majority of the depression from massive dune invasion. However, sand encroachment is clearly observed west of the depression.     

Comparison of Extrapolation and Interpolation Methods for Estimating Daily Photosynthetically Active Radiation(PAR)——A Case Study of the Poyang Lake National Nature Reserve,China

Measurements of photosynthetically active radiation(PAR),which are indispensable for simulating plant growth and productivity,are generally very scarce.This study aimed to compare two extrapolation and one interpolation methods for estimating daily PAR reaching the earth surface within the Poyang Lake national nature reserve,China.The daily global solar radiation records at Nanchang meteorological station and daily sunshine duration measurements at nine meteorological stations around Poyang Lake were obtain...     

Evaluating the performance of a new classifier – the GP-OAD: A comparison with existing methods for classifying rock type and mineralogy from hyperspectral imagery

In this study, we compare three commonly used methods for hyperspectral image classification, namely Support Vector Machines (SVMs), Gaussian Processes (GPs) and the Spectral Angle Mapper (SAM). We assess their performance in combination with different kernels (i.e. which use distance-based and angle-based metrics). The assessment is done in two experiments, under ideal conditions in the laboratory and, separately, in the field (an operational open pit mine) using natural light. For both experiments independent training and test sets are used. Results show that GPs generally outperform the SVMs, irrespective of the kernel used. Furthermore, angle-based methods, including the Spectral Angle Mapper, outperform GPs and SVMs when using distance-based (i.e. stationary) kernels in the field experiment. A new GP method using an angle-based (i.e. a non-stationary) kernel – the Observation Angle Dependent (OAD) covariance function – outperforms SAM and SVMs in both experiments using only a small number of training spectra. These findings show that distance-based kernels are more affected by changes in illumination between the training and test set than are angular-based methods/kernels. Taken together, this study shows that independent training data can be used for classification of hyperspectral data in the field such as in open pit mines, by using Bayesian machine-learning methods and non-stationary kernels such as GPs and the OAD kernel. This provides a necessary component for automated classifications, such as autonomous mining where many images have to be classified without user interaction.     

The XXI Congress of the International Society for Photogrammetry and Remote Sensing（ISPRS） was Held in Beijing

The XXI Congress of the International Society for Photogrammetry and Remote Sensing（ISPRS）, the greatest conference in the community once every four years, was held in Beijing on July 3 to 11, 2008. With the main topic ＂Silk Road for Information from Imagery＂, this congress attracted researchers, scientists and users from all over the world to meet Beijing to exchange their latest achievement,     

Expanding the Sémiologie Graphique for contemporary cartography,some ideas from visual semiotics,art history and design

ABSTRACT

In this article, we describe some ideas based on Bertin’s Sémiologie Graphique with a focus on extending it for aesthetic quality issues in cartography. We consider research in semiotics, aesthetics, and graphic design, with some fruitful results about the use of color or composition. We present several tools, oriented toward a pedagogical use and accessibility, helping to examine the color composition of an expressing image or to create meaningful gradients. While Bertin’s concepts still remain relevant and efficient, specific ideas can be developed further, to adapt to current media and gain from scientific advances from related disciplines.