bluuebunny/crossref_metadata_2025 huggingface dataset:
Do Giant Adrenal Myelolipomas Behave Differently? A Clinicopathological Comparative Study
Authors: Paul MJ , Mukha Rajiv , Cherian Anish Jacob , Paul Thomas V , Abraham Deepak T
Published: May 2013

Adrenal myelolipomas (AM) may present with abdominal distension, pain, rupture, hemorrhage or other complications. Indications for surgery are still debatable. It is possible that larger size may be a risk factor for symptoms or complications in AM. To compare the clinical and pathological characteristics between giant AM (>10 cm) and AM <10 cm. Retrospective data analysis was done on 26 of 32 patients with myelolipoma who underwent surgery between January, 2005 and July, 2012. Patients were divided in two groups: Group 1 (n = 14) with giant AM > 10 cm and group 2 (n = 12) AM < 10 cm. Results were analyzed using independent sample t-test (SPSS v.17). Twenty-six myelolipomas managed surgically were identified from 338 adrenal tumors. None were functioning on biochemical evaluation. Comparing group 1 vs 2, the differences noted were: Commonest age group at presentation was 4th decade vs 5th decade, clinical presentation with abdominal pain was 11 vs 7 (p = 0.05), surgical approach was open in 11 vs 6, and laparoscopic in 3 vs 6 (p = 0.03), mean tumor size was 15.57 vs 6.67 cm, mean tumor weight 794 vs 93 gm, internal hemorrhage on histopathology in 14 vs 10 (p = 0.05). Giant AM have a significantly higher rate of symptomatic presentation, pathological features of hemorrhage and necrosis and requirement for open surgery as compared to myelolipomas <10 cm in our series.

How to cite this article

Ramakant P, Mukha R, Cherian AJ, Naik D, Paul TV, Abraham DT, Paul MJ. Do Giant Adrenal Myelolipomas Behave Differently? A Clinicopathological Comparative Study. World J Endoc Surg 2013;5(1):12-15.
The Surgical Management of Retrosternal (Intrathoracic) Goiter
Authors: Wheeler Malcolm H
Published: May 2013

Retrosternal (intrathoracic) goiter has a prevalence of 4 to 20% of patients undergoing thyroidectomy for multinodular goiter. Although it is a condition affecting the older patient with a peak incidence in the sixth decade, the majority should be treated surgically. With few exceptions the operation can be safely accomplished through a cervical approach, only a small minority (approximately 2%) needing a combined cervical/mediastinal procedure. The surgical steps for the routine case are described and also various technical maneuvers required to facilitate delivery and excision of the difficult large goiter.

How to cite this article

Wheeler MH. The Surgical Management of Retrosternal (Intrathoracic) Goiter. World J Endoc Surg 2013;5(1):28-30.
Observations of total RONO2 over the boreal forest: NOx sinks and HNO3 sources
Authors: Browne E. C. , Min K.-E. , Wooldridge P. J. , Apel E. , Blake D. R. , Brune W. H. , Cantrell C. A. , Cubison M. J. , Diskin G. S. , Jimenez J. L. , Weinheimer A. J. , Wennberg P. O. , Wisthaler A. , Cohen R. C.
Published: May 2013

Abstract. In contrast with the textbook view of remote chemistry where HNO3 formation is the primary sink of nitrogen oxides, recent theoretical analyses show that formation of RONO2 (ΣANs) from isoprene and other terpene precursors is the primary net chemical loss of nitrogen oxides over the remote continents where the concentration of nitrogen oxides is low. This then increases the prominence of questions concerning the chemical lifetime and ultimate fate of ΣANs. We present observations of nitrogen oxides and organic molecules collected over the Canadian boreal forest during the summer which show that ΣANs account for ~20% of total oxidized nitrogen and that their instantaneous production rate is larger than that of HNO3. This confirms the primary role of reactions producing ΣANs as a control over the lifetime of NOx (NOx = NO + NO2) in remote, continental environments. However, HNO3 is generally present in larger concentrations than ΣANs indicating that the atmospheric lifetime of ΣANs is shorter than the HNO3 lifetime. We investigate a range of proposed loss mechanisms that would explain the inferred lifetime of ΣANs finding that in combination with deposition, two processes are consistent with the observations: (1) rapid ozonolysis of isoprene nitrates where at least ~40% of the ozonolysis products release NOx from the carbon backbone and/or (2) hydrolysis of particulate organic nitrates with HNO3 as a product. Implications of these ideas for our understanding of NOx and NOy budget in remote and rural locations are discussed.
Variability in the speed of the Brewer–Dobson circulation as observed by Aura/MLS
Authors: Flury T. , Wu D. L. , Read W. G.
Published: May 2013

Abstract. We use Aura/MLS stratospheric water vapour (H2O) measurements as tracer for dynamics and infer interannual variations in the speed of the Brewer–Dobson circulation (BDC) from 2004 to 2011. We correlate one-year time series of H2O in the lower stratosphere at two subsequent pressure levels (68 hPa, ~18.8 km and 56 hPa, ~19.9 km at the Equator) and determine the time lag for best correlation. The same calculation is made on the horizontal on the 100 hPa (~16.6 km) level by correlating the H2O time series at the Equator with the ones at 40° N and 40° S. From these lag coefficients we derive the vertical and horizontal speeds of the BDC in the tropics and extra-tropics, respectively. We observe a clear interannual variability of the vertical and horizontal branch. The variability reflects signatures of the Quasi Biennial Oscillation (QBO). Our measurements confirm the QBO meridional circulation anomalies and show that the speed variations in the two branches of the BDC are out of phase and fairly well anti-correlated. Maximum ascent rates are found during the QBO easterly phase. We also find that transport of H2O towards the Northern Hemisphere (NH) is on the average two times faster than to the Southern Hemisphere (SH) with a mean speed of 1.15 m s−1 at 100 hPa. Furthermore, the speed towards the NH shows much more interannual variability with an amplitude of about 21% whilst the speed towards the SH varies by only 10%. An amplitude of 21% is also observed in the variability of the ascent rate at the Equator which is on the average 0.2 mm s−1.
A global tropospheric ozone climatology from trajectory-mapped ozone soundings
Authors: Liu G. , Liu J. J. , Tarasick D. W. , Fioletov V. E. , Jin J. J. , Moeni O. , Liu X. , Sioris C. E.
Published: May 2013

Abstract. A global three-dimensional (i.e. latitude, longitude, altitude) climatology of tropospheric ozone is derived from the ozone sounding record by trajectory mapping. Approximately 52 000 ozonesonde profiles from more than 100 stations worldwide since 1962 are used. The small number of stations causes the set of ozone soundings to be sparse in geographical spacing. Here, forward and backward trajectory calculations are performed for each sounding to map ozone measurements to a number of other locations, and so to fill in the spatial domain. This is possible because the lifetime of ozone in the troposphere is of the order of weeks. This physically-based interpolation method offers obvious advantages over typical statistical interpolation methods. The trajectory-mapped ozone values show reasonable agreement, where they overlap, to the actual soundings, and the patterns produced separately by forward and backward trajectory calculations are similar. Major regional features of the tropospheric ozone distribution are clearly evident in the global maps. An interpolation algorithm based on spherical functions is further used for smoothing and to fill in remaining data gaps. The resulting three-dimensional global tropospheric ozone climatology facilitates visualization and comparison of different years, decades, and seasons, and offers some intriguing insights into the global variation of tropospheric ozone. It will be useful for climate and air quality model initialization and validation, and as an a priori climatology for satellite data retrievals. Further division of the climatology into decadal averages provides a global view of tropospheric ozone trends, which appear to be surprisingly modest over the last four decades.
CO profiles from SCIAMACHY observations using cloud slicing and comparison with model simulations
Authors: Liu C. , Beirle S. , Butler T. , Hoor P. , Frankenberg C. , Jöckel P. , Penning de Vries M. , Platt U. , Pozzer A. , Lawrence M. G. , Lelieveld J. , Tost H. , Wagner T.
Published: May 2013

Abstract. We apply a cloud slicing technique (CST), originally developed for Total Ozone Mapping Spectrometer (TOMS) ozone observations, to CO vertical column densities retrieved from the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). CST makes use of the shielding effect of clouds and combines trace gas column measurements of cloudy pixels with different cloud heights to retrieve fractional columns aloft. Here we determine seasonal mean tropospheric CO profiles at a vertical resolution of 1 km, which is much finer than what can be obtained from thermal IR instruments. However, since both the atmospheric CO profiles and the effective cloud heights depend systematically on meteorology, the profiles retrieved from the CST have to be interpreted with care. We compare the seasonal mean SCIAMACHY CO profiles with the output from two atmospheric models sampled in the same way as the satellite observations. We find systematic differences both in the absolute values and vertical and horizontal gradients. The results indicate that vertical (re)distributions of emissions and their strengths are not well represented in the models. It seems likely that deep convective transport is underestimated.
Dry deposition of nitrogen compounds (NO2, HNO3, NH3), sulfur dioxide and ozone in West and Central African ecosystems using the inferential method
Authors: Adon M. , Galy-Lacaux C. , Yoboue V. , Delon C. , Solmon F. , Kaptue Tchuente A. T.
Published: May 2013

Abstract. This work is part of the IDAF program (IGAC-DEBITS-AFRICA) and is based on the long term monitoring of gas concentrations (1998–2007) established on seven remote sites representative of major African ecosystems. Dry deposition fluxes were estimated by the inferential method using on one hand surface measurements of gas concentrations (NO2, HNO3, NH3, SO2, and O3) and on the other hand simulated dry deposition velocities (Vd). Vd were calculated using the big-leaf model of Zhang et al. (2003b). In the model of deposition, surface and meteorological conditions specific to IDAF sites have been adapted in order to simulate Vd representative of major African ecosystems. The monthly, seasonal and annual mean variations of gaseous dry deposition fluxes (NO2, HNO3, NH3, O3, and SO2) are analyzed. Along the latitudinal transect of ecosystems, the annual mean dry deposition fluxes of nitrogen compounds range from 0.4 ± 0.0 to 0.8 ± 0.2 kg N ha−1 yr−1 for NO2, from 0.7 ± 0.1 to 1.0 ± 0.3 kg N ha−1 yr−1 for HNO3, and from 2.3 ± 0.8 to 10.5 ± 5.0 kg N ha−1 yr−1 for NH3 over the study period (1998–2007). The total nitrogen dry deposition flux (NO2+HNO3+NH3) is more important in forests (11.2–11.8 kg N ha−1 yr−1) than in wet and dry savannas (3.4–5.3 kg N ha−1 yr−1). NH3 dominated nitrogen dry deposition, representing 67–80% of the total. The annual mean dry deposition fluxes of ozone range between 11.3 ± 4.7 and 17.5 ± 3.0 kg ha−1 yr−1 in dry savannas, 17.5 ± 3.0 and 19.2 ± 2.9 kg ha−1 yr−1 in wet savannas, and 10.6 ± 2.0 and 13.2 ± 3.6 kg ha−1 yr−1 in forests. Lowest O3 dry deposition fluxes in forests are correlated to low measured O3 concentrations, lower of a factor of 2–3, compared to others ecosystems. Along the ecosystem transect, annual mean of SO2 dry deposition fluxes present low values and a small variability (0.5 to 1 kg S ha−1 yr−1). No specific trend in the interannual variability of these gaseous dry deposition fluxes is observed over the study period.
Calibration of the passive cavity aerosol spectrometer probe for airborne determination of the size distribution
Authors: Cai Y. , Snider J. R. , Wechsler P.
Published: May 2013

Abstract. This work describes calibration methods for the particle sizing and particle concentration systems of the passive cavity aerosol spectrometer probe (PCASP). Laboratory calibrations conducted over six years, in support of the deployment of a PCASP on a cloud physics research aircraft, are analyzed. Instead of using the many calibration sizes recommended by the PCASP manufacturer, a relationship between particle diameter and scattered light intensity is established using three sizes of mobility-selected polystyrene latex particles, one for each amplifier gain stage. In addition, studies of two factors influencing the PCASP's determination of the particle size distribution – amplifier baseline and particle shape – are conducted. It is shown that the PCASP-derived size distribution is sensitive to adjustments of the sizing system's baseline voltage, and that for aggregate spheres, a PCASP-derived particle size and a sphere-equivalent particle size agree within uncertainty dictated by the PCASP's sizing resolution. Robust determination of aerosol concentration, and size distribution, also require calibration of the PCASP's aerosol flowrate sensor. Sensor calibrations, calibration drift, and the sensor's non-linear response are documented.
Interconnectivity vs. isolation of prokaryotic communities in European deep-sea mud volcanoes
Authors: Pachiadaki M. G. , Kormas K. A.
Published: May 2013

Abstract. During the past two decades, European cold seep ecosystems have attracted the scientific interest and to date there are several studies which have investigated the community structure and biodiversity of individual sites. In order to gain a better insight into the biology, biodiversity, and biogeography of seep-associated microbial communities along Europe's continental margins, a comparative approach was applied in the present work. By exploiting the publicly available data on 16S rRNA gene sequences retrieved from sediments of the Håkon Mosby mud volcano, Gulf of Cádiz and the eastern Mediterranean mud volcanoes/pockmarks (Anaximander area and Nile Fan), we investigated the prokaryotic biological components connecting these geographically isolated systems. The construction of interaction networks for both archaeal and bacterial shared operational taxonomic units (OTUs) among the different sites, revealed the presence of persistent OTUs, which can be considered as "key-players". One archaeal OTU (HQ588641) belonging to the ANME-3 group and one δ-Proteobacteria (HQ588562) were found in all five investigated areas. Other Archaea OTUs shared between four sites or less, belonged to the ANME-2c, -2a, MBG-D, -B and Thaumarchaeota. All other shared Bacteria belonged to the δ- and γ-Proteobacteria, with the exception of one JS1 affiliate OTU. The distribution of the majority of the shared OTUs seems to be restricted in cold seeps, mud volcanoes and other marine methane-rich environments. Although the investigated sites were connected through a small number of OTUs, these microorganisms hold central ecophysiological roles in these sediments, namely methane- and sulfur-mediated mineralization.
Annual carbon balance of a peatland 10 yr following restoration
Authors: Strack M. , Zuback Y. C. A.
Published: May 2013

Abstract. Undisturbed peatlands represent long-term net sinks of carbon; however, peat extraction converts these systems into large and persistent sources of greenhouse gases. Although rewetting and restoration following peat extraction have taken place over the last several decades, very few studies have investigated the longer term impact of this restoration on peatland carbon balance. We determined the annual carbon balance of a former horticulturally-extracted peatland restored 10 yr prior to the study and compared these values to the carbon balance measured at neighboring unrestored and natural sites. Carbon dioxide (CO2) and methane (CH4) fluxes were measured using the chamber technique biweekly during the growing season from May to October 2010 and three times over the winter period. Dissolved organic carbon (DOC) export was measured from remnant ditches in the unrestored and restored sites. During the growing season the restored site had greater uptake of CO2 than the natural site when photon flux density was greater than 1000 μmol m−2 s−1, while the unrestored site remained a source of CO2. Ecosystem respiration was similar between natural and restored sites, which were both significantly lower than the unrestored site. Methane flux remained low at the restored site except from open water pools, created as part of restoration, and remnant ditches. Export of DOC during the growing season was 5.0 and 28.8 g m−2 from the restored and unrestored sites, respectively. Due to dry conditions during the study year all sites acted as net carbon sources with annual balance of the natural, restored and unrestored sites of 250.7, 148.0 and 546.6 g C m−2, respectively. Although hydrological conditions and vegetation community at the restored site remained intermediate between natural and unrestored conditions, peatland restoration resulted in a large reduction in annual carbon loss from the system resulting in a carbon balance more similar to a natural peatland.
Removal and transformation of pharmaceuticals in wastewater treatment plants and constructed wetlands
Authors: Lee E. , Lee S. , Park J. , Kim Y. , Cho J.
Published: May 2013

Abstract. Since trace organic compounds such as pharmaceuticals in surface water have been a relevant threat to drinking water supplies, in this study the removal of pharmaceuticals and transformation of pharmaceuticals into metabolites were investigated in the main sources of micropollutants such as wastewater treatment plants (WWTPs) and engineered constructed wetlands. Pharmaceuticals were effectively removed by different WWTP processes and wetlands. Pharmaceutical metabolites with relatively low log D value resulted in the low removal efficiencies compared to parent compounds with relatively high log D value, indicating the stability of metabolites. And the constructed wetlands fed with wastewater effluent were encouraged to prevent direct release of micropollutants into surface waters. Among various pharmaceuticals, different transformation pattern of ibuprofen was observed with significant formation of 1-hydroxy-ibuprofen during biological treatment in WWTP, indicating preferential biotransformation of ibuprofen. Lastly, transformation of pharmaceuticals depending on their structural position was investigated in terms of electron density, and the electron rich C1 = C2 bond of carbamazepine was revealed as an initial transformation position.
Streamflow input to Lake Athabasca, Canada
Authors: Rasouli K. , Hernández-Henríquez M. A. , Déry S. J.
Published: May 2013

Abstract. The Lake Athabasca drainage area in northern Canada encompasses ecologically rich and sensitive ecosystems, vast forests, glacier-clad mountains, and abundant oil reserves in the form of oil sands. The basin includes the Peace–Athabasca Delta, recognized internationally by UNESCO and the Ramsar Convention as a biologically rich inland delta and wetland that are now under increasing pressure from multiple stressors. In this study, streamflow variability and trends for rivers feeding Lake Athabasca are investigated over the last half century. Hydrological regimes and trends are established using a robust regime shift detection method and the Mann–Kendall (MK) test, respectively. Results show that the Athabasca River, which is the main contributor to the total lake inflow, experienced marked declines in recent decades impacting lake levels and its ecosystem. From 1960 to 2010 there was a significant reduction in lake inflow and a significant recession in the Lake Athabasca level. Our trend analysis corroborates a previous study using proxy data obtained from nearby sediment cores suggesting that the lake level may drop 2 to 3 m by 2100. The lake recession may threaten the flora and fauna of the Athabasca Lake basin and negatively impact the ecological cycle of an inland freshwater delta and wetland of global importance.
Anomalous frequency characteristics of groundwater level before major earthquakes in Taiwan
Authors: Chen C.-H. , Wang C.-H. , Wen S. , Yeh T.-K. , Lin C.-H. , Liu J.-Y. , Yen H.-Y. , Lin C. , Rau R.-J. , Lin T.-W.
Published: May 2013

Abstract. Unusual decreases of water levels were consistently observed in 78% (= 42/54) of wells in the Choshuichi Alluvial Fan of central Taiwan about 250 days before the Chi-Chi earthquake (M = 7.6 on 20 September 1999) while possible factors of barometric pressure, earth tides, precipitation as well as artificial pumping were removed. Variations in groundwater levels measured on anomalous wells from 1 August 1997 to 19 September 1999, which covers the 250 day unusual decreases, were transferred into the frequency domain to unveil frequency characteristics associated with the Chi-Chi earthquake. Analytical results show that amplitudes at the frequency band between 0.02 day−1 and 0.04 day−1 generally maintained at the low stage and were apparently enhanced a few weeks before the Chi-Chi earthquake. Variations of amplitude at this particular frequency band were further examined along with other Taiwan earthquakes (M > 6) from 1 August 1997 to 31 December 2009. Features of the enhanced amplitudes at the frequency band are consistently observed prior to the other two earthquakes (the Rei-Li and Ming-Jian earthquakes) during the 12.5 yr study period. In addition, surface displacements recorded from GPS, which provides insights into understanding stress status in subsurface during the Chi-Chi earthquake, are also inspected. The result confirms that abnormal rise and fall changes in groundwater level yield an agreement with forward and backward surface displacements around the epicentre prior to the Chi-Chi earthquake.
INTEGRATION OF LIDAR DATA INTO A MUNICIPAL GIS TO STUDY SOLAR RADIATION
Authors: Africani P. , Bitelli G. , Lambertini A. , Minghetti A. , Paselli E.
Published: May 2013

Abstract. Identifying the right roofs to install solar panels inside a urban area is crucial for both private citizens and the whole local population. The aim is not easy because a lot of consideration must be made: insolation, orientation of the surface, size of the surface, shading due to topography, shading due to taller buildings next the surface, shading due to taller vegetation and other possible problems typical of urban areas like the presence of chimneys. Accuracy of data related to the analyzed surfaces is indeed fundamental, and also the detail of geometric models used to represent buildings and their roofs. The complexity that these roofs can reach is elevated. This work uses LiDAR data to obtain, with a semi-automatic technique, the full geometry of each roof part complementing the pre-existing building data in the municipal cartography. With this data is possible to evaluate the placement of solar panels on roofs of a whole city analyzing the solar potential of each building in detail. Other traditional techniques, like photogrammetry, need strong manual editing effort in order to identify slopes and insert vector on surfaces at the right height. Regarding LiDAR data, in order to perform accurate modelling, it is necessary to obtain an high density point cloud. The method proposed can also be used as a fast and linear workflow process for an area where LiDAR data are available and a municipal cartography already exist: LiDAR data can be furthermore successfully used to cross-check errors in pre-existent digital cartography that can remain otherwise hidden.
REFERENCE LIDAR SURFACES FOR ENHANCED AERIAL TRIANGULATION AND CAMERA CALIBRATION
Authors: Gneeniss A. S. , Mills J. P. , Miller P. E.
Published: May 2013

Abstract. Due to the complementary characteristics of lidar and photogrammetry, the integration of data derived from these techniques continues to receive attention from the relevant research communities. The research presented in this paper draws on this by adopting lidar data as a control surface from which aerial triangulation and camera system calibration can be performed. The research methodology implements automatic registration between the reference lidar DTM and dense photogrammetric point clouds which are derived using Integrated Sensing Orientation (ISO). This utilises a robust least squares surface matching algorithm, which is iterated to improve results by increasing the photogrammetric point quality through self-calibrating bundle adjustment. After a successful registration, well distributed lidar control points (LCPs) are automatically extracted from the transformed photogrammetric point clouds using predefined criteria. Finally, self-calibrating bundle block adjustment using different configurations of LCPs is performed to refine camera interior orientation (IO) parameters. The methodology has been assessed using imagery from a Vexcel UltraCamX large format camera. Analysis and the performance of the camera and its impact on the registration accuracy was performed. Furthermore, refinement of camera IO parameters was also applied using the derived LCPs. Tests also included investigations into the influence of the number and weight of LCPs in the accuracy of the bundle adjustment. Results from the UltraCamX block were compared with reference calibration results using ground control points in the test area, with good agreement found between the two approaches.
APPROACH FOR THE SEMI-AUTOMATIC VERIFICATION OF 3D BUILDING MODELS
Authors: Helmholz P. , Belton D. , Moncrieff S.
Published: May 2013

Abstract. In the field of spatial sciences, there are a large number of disciplines and techniques for capturing data to solve a variety of different tasks and problems for different applications. Examples include: traditional survey for boundary definitions, aerial imagery for building models, and laser scanning for heritage facades. These techniques have different attributes such as the number of dimensions, accuracy and precision, and the format of the data. However, because of the number of applications and jobs, often over time these data sets captured from different sensor platforms and for different purposes will overlap in some way. In most cases, while this data is archived, it is not used in future applications to value add to the data capture campaign of current projects. It is also the case that newly acquire data are often not used to combine and improve existing models and data integrity. The purpose of this paper is to discuss a methodology and infrastructure to automatically support this concept. That is, based on a job specification, to automatically query existing and newly acquired data based on temporal and spatial relations, and to automatically combine and generate the best solution. To this end, there are three main challenges to examine; change detection, thematic accuracy and data matching.
EUFODOS: European Forest Downstream Services – Improved Information on Forest Structure and Damage
Authors: Hirschmugl M. , Gallaun H. , Wack R. , Granica K. , Schardt M.
Published: May 2013

Abstract. Forests play a key role in the European economy and environment. This role incorporates ecological functions which can be affected by the occurrence of insect infestations, forest fire, heavy snowfall or windfall events. Local or Regional Authorities (LRAs) thus require detailed information on the degradation status of their forests to be able to take appropriate measures for their forest management plans. In the EUFODOS project, state-of-the-art satellite and laser scanning technologies are used to provide forest authorities with cost-effective and comprehensive information on forest structure and damage. One of the six test sites is located in the Austrian province of Styria where regional forest authorities have expressed a strong need for detailed forest parameters in protective forest. As airborne laser-scanning data is available, it will be utilized to derive detailed forest parameters such as the upper forest border line, tree height, growth classes, forest density, vertical structure or volume. At the current project status, the results of (i) the forest border line, (ii) the segmentation of forest stands and (iii) the tree top detection are available and presented including accuracy assessment and interim results are shown for timber volume estimations. The final results show that the forest border can be mapped operationally with an overall accuracy of almost 99% from LiDAR data. For the segmentation of forest stands, a comparison of the automatically derived result with visual-manual delineation showed in general a more detailed segmentation result, but for all visual-manual segments a congruence of 87% within a 4 m buffer. Tree top detections were compared to stem numbers estimated based on angle-count samplings in a field campaign, which led to a correlation coefficient (R) of 0.79.
THE EFFECT OF DIFFERENT GNSS SOLUTIONS ON THE DIRECT SENSOR ORIENTATION ACCURACY
Authors: Kayi A. , Yilmaz H. M. , Yilmaz A.
Published: May 2013

Abstract. Direct sensor orientation or direct georeferencing is the solution of exterior orientation parameters using GNSS\\IMU data without ground control points. Accuracy of the system is based on GNSS\\IMU integrated system accuracy. The integrated system containing DGNSS and IMU calculates the approximate exterior orientation parameters during the flight. The exterior orientation accuracy is based on GNSS and IMU accuracy. In this study, the effect of single point, network and PPP GNSS data processes without ground control point on the accuracy of the direct sensor orientation was evaluated. The area of the test region is approximately 1296 km 2. 393 images with 30 cm resolution were used in the study. It was calculated that single point solution horizontal accuracies are (XY) ± 23–30 cm., vertical accuracy is (Z) ± 40cm, network solution horizontal accuracies are (X-Y) ± 24-27 cm, vertical accuracy is (Z) ± 37 cm and PPP solution horizontal accuracies are (X-Y) ± 20–28 cm, vertical accuracy is (Z) ± 37 cm.
BACKSCATTERING OF INDIVIDUAL LIDAR PULSES FROM FOREST CANOPIES EXPLAINED BY PHOTOGRAMMETRICALLY DERIVED VEGETATION STRUCTURE
Authors: Korpela I. , Hovi A. , Korhonen L.
Published: May 2013

Abstract. In recent years, airborne LiDAR sensors have shown remarkable performance in the mapping of forest vegetation. This experimental study looks at LiDAR data at the scale of individual pulses to elucidate the sources behind interpulse variation in backscattering. Close-range photogrammetry was used for obtaining the canopy reference measurements at the ratio scale. The experiments illustrated different orientation techniques in the field, LiDAR acquisitions and photogrammetry in both leaf-on and leaf-off conditions, and two-waveform recording LiDAR sensors. The intrafootprint branch silhouettes in zenith-looking images, in which the camera, footprint, and LiDAR sensor were collinear, were extracted and contrasted with LiDAR backscattering. An enhanced planimetric match (refinement of strip matching) was achieved by shifting the pulses in a strip and searching for the maximal correlation between the silhouette and LiDAR intensity. The relative silhouette explained up to 80–90% of the interpulse variation. We tested whether accounting for the Gaussian spread of intrafootprint irradiance would improve the correlations, but the effect was blurred by small-scale geometric noise. Accounting for receiver gain variations in the Leica ALS60 sensor data strengthened the dependences. The size of the vegetation objects required for triggering a LiDAR observation was analyzed. We demonstrated the use of LiDAR pulses adjacent to canopy vegetation, which did not trigger a canopy echo, for canopy mapping. Pulses not triggering an echo constitute the complement to the actual canopy. We conclude that field photogrammetry is a useful tool for mapping forest canopies from below and that quantitative analysis is feasible even at the scale of single pulses for enhanced understanding of LiDAR observations from vegetation.
RAPID ACQUISITION OF ENVIRONMENTAL INFORMATION AFTER ACCIDENTS WITH HAZARDOUS CARGO THROUGH REMOTE SENSING BY UAV
Authors: Longhitano G. A. , Quintanilh J. A.
Published: May 2013

Abstract. The aim of the study was to present procedures of using remote sensing by UAV to aid in the rapid evaluation and monitoring of environmental impacts caused by accidents involving transport of dangerous cargoes on highways. From the data collected and the UAV model defined, it was developed a methodology of operating a UAV to generate the potential benefits identified in the application. A Mini UAV or Close Range class was considered appropriate. It was created the procedures for imaging, the emergency activation of an UAV, the generation parameters of the images and forms of environmental information extraction. The study does not eliminate the necessity of testing the technology for this application, but indicates the possibility of generating more detailed and faster information.
ROADS CENTRE-AXIS EXTRACTION IN AIRBORNE SAR IMAGES: AN APPROACH BASED ON ACTIVE CONTOUR MODEL WITH THE USE OF SEMI-AUTOMATIC SEEDING
Authors: Lotte R. G. , Sant'Anna S. J. S. , Almeida C. M.
Published: May 2013

Abstract. Research works dealing with computational methods for roads extraction have considerably increased in the latest two decades. This procedure is usually performed on optical or microwave sensors (radar) imagery. Radar images offer advantages when compared to optical ones, for they allow the acquisition of scenes regardless of atmospheric and illumination conditions, besides the possibility of surveying regions where the terrain is hidden by the vegetation canopy, among others. The cartographic mapping based on these images is often manually accomplished, requiring considerable time and effort from the human interpreter. Maps for detecting new roads or updating the existing roads network are among the most important cartographic products to date. There are currently many studies involving the extraction of roads by means of automatic or semi-automatic approaches. Each of them presents different solutions for different problems, making this task a scientific issue still open. One of the preliminary steps for roads extraction can be the seeding of points belonging to roads, what can be done using different methods with diverse levels of automation. The identified seed points are interpolated to form the initial road network, and are hence used as an input for an extraction method properly speaking. The present work introduces an innovative hybrid method for the extraction of roads centre-axis in a synthetic aperture radar (SAR) airborne image. Initially, candidate points are fully automatically seeded using Self-Organizing Maps (SOM), followed by a pruning process based on specific metrics. The centre-axis are then detected by an open-curve active contour model (snakes). The obtained results were evaluated as to their quality with respect to completeness, correctness and redundancy.
OPERATIONAL SAR DATA PROCESSING IN GIS ENVIRONMENTS FOR RAPID DISASTER MAPPING
Authors: Meroni A. , Bahr T.
Published: May 2013

Abstract. Having access to SAR data can be highly important and critical especially for disaster mapping. Updating a GIS with contemporary information from SAR data allows to deliver a reliable set of geospatial information to advance civilian operations, e.g. search and rescue missions. Therefore, we present in this paper the operational processing of SAR data within a GIS environment for rapid disaster mapping. This is exemplified by the November 2010 flash flood in the Veneto region, Italy. A series of COSMO-SkyMed acquisitions was processed in ArcGIS® using a single-sensor, multi-mode, multi-temporal approach. The relevant processing steps were combined using the ArcGIS ModelBuilder to create a new model for rapid disaster mapping in ArcGIS, which can be accessed both via a desktop and a server environment.
DATA PROCESSING CONCEPTS FOR THE INTEGRATION OF SAR INTO OPERATIONAL VOLCANO MONITORING SYSTEMS
Authors: Meyer F. J. , McAlpin D. B. , Gong W. , Arko S. , Webley P. W. , Dehn J.
Published: May 2013

Abstract. Remote Sensing plays a critical role in operational volcano monitoring due to the often remote locations of volcanic systems and the large spatial extent of potential eruption pre-cursor signals. Despite the all-weather capabilities of radar remote sensing and despite its high performance in monitoring change, the contribution of radar data to operational monitoring activities has been limited in the past. This is largely due to (1) the high data costs associated with radar data, (2) the slow data processing and delivery procedures, and (3) the limited temporal sampling provided by spaceborne radars. With this paper, we present new data processing and data integration techniques that mitigate some of the above mentioned limitations and allow for a meaningful integration of radar remote sensing data into operational volcano monitoring systems. The data integration concept presented here combines advanced data processing techniques with fast data access procedures in order to provide high quality radar-based volcano hazard information at improved temporal sampling rates. First performance analyses show that the integration of SAR can significantly improve the ability of operational systems to detect eruptive precursors. Therefore, the developed technology is expected to improve operational hazard detection, alerting, and management capabilities.
INVESTIGATION ON CIRCULAR MAPPING BY FMCW-SAR ON SMALL AIRPLANES
Authors: Palm S. , Maresch A. , Stilla U.
Published: May 2013

Abstract. The evaluation of local damages after natural disasters by using remote sensing demands for flexible platforms as well as sensor systems, which guarantee both weather- and daylight-independence. Due to the fact of small energy consumption, small size and light weight millimeter-wave FMCW radar sensors on small airplanes are very promising for this task. Especially in urban environments the side looking SAR geometry causes shadowing and foreshortening effects, which lead to gaps in the reconstructed scene and misinterpretation. Multiple views from different aspect angles can reduce the shadowing effects but especially in unknown areas the best line of sight cannot be investigated in advance. This is achievable by perfoming circular flight trajectories. However, as millimeter-wave FMCW radar sensors typically have very narrow beams and small airplanes are sensitive to air turbulences, a beam stabilization method is necessary to provide full illumination of the target scene. In this paper the calculations for system specific optimal flight parameters are demonstrated and validated by simulations. The impact of air turbulences, causing angular deviations to the sensor and thus misplacement of the main beam lobe on the ground are explored by experimental data performed with our SUMATRA system. The effects of a potential mechanical beam stabilization are visualized and requirements for such a system are formulated. Our experiments show that for typical flight conditions a stabilized platform is well suitable to stabilize a narrow radar beam in order to keep a target scene constantly illuminated over a full circular trajectory. Typically these stabilized platforms can handle angular corrections in all three geometries (pitch, roll, squint) of up to 12 °−15 ° by a speed of 15 ° per second. Therefore a more cost intensive full gimbal system which is known to be used in optical applications and which can handle a full 360 ° tracking is not neccessarily needed.
EVALUATION OF PLEIADES-1A TRIPLET ON TRENTO TESTFIELD
Authors: Poli D. , Remondino F. , Angiuli E. , Agugiaro G.
Published: May 2013

Abstract. The Pleiades mission is part of the French-Italian ORFEO system (Optical and Radar Federated Earth Observation) and has the aim to provide very-high resolution optical imagery from space for civilian and military needs. Within the Pleiades evaluation program, the 3DOM Unit at the Bruno Kessler Foundation in Trento (Italy) received a triplet by Pleiades-1A over Trento testfield for research purposes. The images composing the triplet were acquired on August 28, 2012 with across-track angles close to nadir and alongtrack angles of 18°, -13° and 13° in average with respect to the flight direction (Fig. 1) and a mean GSD between 0.72 m and 0.78 m. The aim of this paper is to investigate the quality of the Pleiades triplet and derived Digital Surface Model (DSM). The image analysis was conducted by evaluating the radiometric properties of the images (noise characteristics, image artifacts, spilling) and the geometric accuracy. After image orientation, three DSMs were generated with advanced image matching algorithms using two image combinations and the triplet. The DSMs were compared to the reference Lidar DSM (1 m grid spacing) for quality analysis in areas with different characteristics (land use and cover, topography). Thanks to the availability of other very high resolution satellite imagery in the testfield, the results were compared to those previously obtained using WorldView-2 ad GeoEye-1 stereopairs acquired on the same area.
CLASSIFICATION OF WATER SURFACES USING AIRBORNE TOPOGRAPHIC LIDAR DATA
Authors: Smeeckaert J. , Mallet C. , David N.
Published: May 2013

Abstract. Accurate Digital Terrain Models (DTM) are inevitable inputs for mapping areas subject to natural hazards. Topographic airborne laser scanning has become an established technique to characterize the Earth surface: lidar provides 3D point clouds allowing a fine reconstruction of the topography. For flood hazard modeling, the key step before terrain modeling is the discrimination of land and water surfaces within the delivered point clouds. Therefore, instantaneous shoreline, river borders, inland waters can be extracted as a basis for more reliable DTM generation. This paper presents an automatic, efficient, and versatile workflow for land/water classification of airborne topographic lidar data. For that purpose, a classification framework based on Support Vector Machines (SVM) is designed. First, a restricted set of features, based only 3D lidar point coordinates and flightline information, is defined. Then, the SVM learning step is performed on small but well-targeted areas thanks to an automatic region growing strategy. Finally, label probabilities given by the SVM are merged during a probabilistic relaxation step in order to remove pixel-wise misclassification. Results show that survey of millions of points are labelled with high accuracy (>95% in most cases for coastal areas, and >89% for rivers) and that small natural and anthropic features of interest are still well classified though we work at low point densities (0.5–4 pts/m2). Our approach is valid for coasts and rivers, and provides a strong basis for further discrimination of land-cover classes and coastal habitats.
HIGH RESOLUTION TEMPORAL NORMALIZED DIFFERENCE VEGETATION INDICES FOR SPECIFIC CROP IDENTIFICATION
Authors: Upadhyay P. , Ghosh S. K. , Kumar A.
Published: May 2013

Abstract. In many applications of the remote sensing, an user is often interested in identifying specific land cover only while other classes may be of no interest. In the present study, high resolution WorldView-2 image having spatial resolution of 1.84 meter has been used for identifying wheat crop for a test site located in Roorkee, India. WorldView-2 data consists of a total of eight spectral bands out of which last four spectral bands i.e. Red (630–690 nm), Red edge (705–745 nm), NIR 1 (770–895 nm) and NIR 2 (860–1040 nm) are useful for the vegetation related studies. Since Normalized Difference Vegetation Index (NDVI) which is formulated by the Red and NIR band, is well known for vegetation related studies. Therefore, in the present research the above four bands has been used to generate all the four possible combinations of NDVI viz. Red – NIR1, Red edge – NIR 1, Red – NIR 2 and Red edge – NIR 2. Further to study the temporal behaviour of crops, two date WorldView-2 data was taken to make the temporal NDVI. These temporal NDVI were then classified using fuzzy based Possibilistic c-Means (PCM) soft classification. The weighting exponent (or fuzzifier) m was optimized to get the best PCM soft classification output. Wheat crop is represented as the fraction image output of the PCM soft classification corresponding to each temporal NDVI. To check the accuracy of these fraction images, the entropy method was used. The entropy values were calculated for a total of 150 known pixels in each output. It is found that the outputs corresponding to low entropy values have sufficiently high membership values for wheat class, hence these outputs are more accurate. Further, it is observed that the average entropy values found for the temporal NDVI corresponding to the Red – NIR 1, Red edge – NIR 1, Red – NIR 2 and Red edge – NIR 2 are 0.065, 0.089, 0.075 and 0.055 respectively. Thus, it can be concluded that temporal NDVI generated by using a combination of Red edge and NIR-2 bands yields higher accuracies in comparison to other. It was also observed from the study that the optimized values of weighting exponent m is varies for different spectral indices.
ANALYSIS OF X-BAND VERY HIGH RESOLUTION PERSISTENT SCATTERER INTERFEROMETRY DATA OVER URBAN AREAS
Authors: Crosetto M. , Monserrat O. , Cuevas-González M. , Devanthéry N. , Crippa B.
Published: May 2013

Abstract. Persistent Scatterer Interferometry (PSI) is a satellite-based Synthetic Aperture Radar (SAR) remote sensing technique used to measure and monitor land deformation from a stack of interferometric SAR images. This work concerns X-band PSI and, in particular, PSI based on very high resolution (VHR) StripMap CosmoSkyMed and TerraSAR-X SAR imagery. In fact, it mainly focuses on the technical aspects of deformation measurement and monitoring over urban areas. A key technical aspect analysed in this paper is the thermal expansion component of PSI observations, which is a result of temperature differences in the imaged area between SAR acquisitions. This component of PSI observations is particularly important in the urban environment. This is an interesting feature of PSI, which can be surely used to illustrate the high sensitivity of X-band PSI to very subtle displacements. Thermal expansion can have a strong impact on the PSI products, especially on the deformation velocity maps and deformation time series, if not properly handled during the PSI data processing and analysis, and a comprehensive discussion of this aspect will be provided in this paper. The importance of thermal expansion is related to the fact that the PSI analyses are often performed using limited stacks of images, which may cover a limited time period, e.g. several months only. These two factors (limited number of images and short period) make the impact of a non-modelled thermal expansion particularly critical. This issue will be illustrated considering different case studies based on TerraSAR-X and CosmoSkyMed PSI data. Besides, an extended PSI model which alleviates this problem will be described and case studies from the Barcelona metropolitan area will demonstrate the effectiveness of the proposed strategy.
EVALUATION OF ZY-3 FOR DSM AND ORTHO IMAGE GENERATION
Authors: d'Angelo P.
Published: May 2013

Abstract. DSM generation using stereo satellites is an important topic for many applications. China has launched the three line ZY-3 stereo mapping satellite last year. This paper evaluates the ZY-3 performance for DSM and orthophoto generation on two scenes east of Munich. The direct georeferencing performance is tested using survey points, and the 3D RMSE is 4.5 m for the scene evaluated in this paper. After image orientation with GCPs and tie points, a DSM is generated using the Semi-Global Matching algorithm. For two 5 × 5 km2 test areas, a LIDAR reference DTM was available. After masking out forest areas, the overall RMSE between ZY-3 DSM and LIDAR reference is 2.0 m (RMSE). Additionally, qualitative comparison between ZY-3 and Cartosat-1 DSMs is performed.