The Experts below are selected from a list of 12183 Experts worldwide ranked by ideXlab platform
Terry L Pavlis - One of the best experts on this subject based on the ideXlab platform.
-
Positional Accuracy of the google earth terrain model derived from stratigraphic unconformities in the big bend region texas usa
Geocarto International, 2011Co-Authors: Christian S Benker, Richard P Langford, Terry L PavlisAbstract:The Google Earth terrain model could prove beneficial for extraction of Positional data in the future. At present, only an aging independent benchmark study (Potere, D., 2008. Horizontal position Accuracy of Google Earth's high-resolution imagery archive. Sensors, 8, 7973–7981) provides constraints on Positional Accuracy for Google Earth imagery. In this investigation, we compared virtually traced positions against high-precision (<1 m) field measurements along three stratigraphic unconformity sub-sections in the Big Bend region to determine current Positional Accuracy for the Google Earth terrain model. A horizontal position Accuracy of 2.64 m RMSEr was determined for the Google Earth terrain model with mean offset distance being 6.95 m. A vertical position Accuracy of 1.63 m RMSEz with mean offset distance of 2.66 m was also calculated for the terrain model. Results suggest data extracted from the Google Earth terrain model could plausibly be used in future studies. However, we urge caution in using Goo...
-
Positional Accuracy of the Google Earth terrain model derived from stratigraphic unconformities in the Big Bend region, Texas, USA
Geocarto International, 2011Co-Authors: S. Christian Benker, Richard P Langford, Terry L PavlisAbstract:The Google Earth terrain model could prove beneficial for extraction of Positional data in the future. At present, only an aging independent benchmark study (Potere, D., 2008. Horizontal position Accuracy of Google Earth's high-resolution imagery archive. Sensors, 8, 7973–7981) provides constraints on Positional Accuracy for Google Earth imagery. In this investigation, we compared virtually traced positions against high-precision (
Shweta Shah - One of the best experts on this subject based on the ideXlab platform.
-
an observational review on influence of intense geomagnetic storm on Positional Accuracy of navic irnss system
Iete Technical Review, 2020Co-Authors: Mehul V. Desai, Shweta ShahAbstract:The Positional Accuracy of Navigation with the Indian Constellation (NavIC)/Indian Regional Navigation Satellite System (IRNSS) in the low latitudes of the Indian region during the intense geomagne...
-
An Observational Review on influence of Intense Geomagnetic Storm on Positional Accuracy of NavIC/IRNSS System
IETE Technical Review, 2019Co-Authors: Mehul V. Desai, Shweta ShahAbstract:The Positional Accuracy of Navigation with the Indian Constellation (NavIC)/Indian Regional Navigation Satellite System (IRNSS) in the low latitudes of the Indian region during the intense geomagne...
-
The GIVE Ionospheric Delay Correction Approach to Improve Positional Accuracy of NavIC/IRNSS Single-Frequency Receiver
Current Science, 2018Co-Authors: Mehul V. Desai, Shweta ShahAbstract:The Navigation with Indian Constellation (NavIC)/Indian Regional Navigation Satellite System (IRNSS) is an independent navigation system developed for the Indian subcontinent by the Indian Space Research Organisation (ISRO). The Positional Accuracy of this system is mainly affected by the ionosphere of the low-latitude equatorial Indian subcontinent, as large ionospheric gradients and intense irregularities are present in it. The objective of this study is to improve the Positional Accuracy of NavIC/IRNSS systems by applying ionospheric correction using the most suitable single-frequency model. The data to be analysed were collected from the NavIC/IRNSS receiver provided by the Space Applications Centre, ISRO. A comparative analysis between the dual-frequency model and single-frequency model (e.g. GIVE model, coefficient-based model) was performed on the data from the NavIC/IRNSS receiver. Different ionospheric models were applied to compute ionospheric delay (ionodelay) on a quiet day (3 < K P < 5). Our result shows that both the single-frequency Grid Ionosphere Vertical Error (GIVE) model and dual frequency model outperform remarkably compared to the traditional coefficient-based model. The GIVE model was also analysed on FAR categorized satellites for different stormy days of different months. It was observed that during stormy days also, the 3D position computed by applying the GIVE model was nearly the same as the dual-frequency model.
-
the give ionospheric delay correction approach to improve Positional Accuracy of navic irnss single frequency receiver
Current Science, 2018Co-Authors: Mehul V. Desai, Shweta ShahAbstract:The Navigation with Indian Constellation (NavIC)/Indian Regional Navigation Satellite System (IRNSS) is an independent navigation system developed for the Indian subcontinent by the Indian Space Research Organisation (ISRO). The Positional Accuracy of this system is mainly affected by the ionosphere of the low-latitude equatorial Indian subcontinent, as large ionospheric gradients and intense irregularities are present in it. The objective of this study is to improve the Positional Accuracy of NavIC/IRNSS systems by applying ionospheric correction using the most suitable single-frequency model. The data to be analysed were collected from the NavIC/IRNSS receiver provided by the Space Applications Centre, ISRO. A comparative analysis between the dual-frequency model and single-frequency model (e.g. GIVE model, coefficient-based model) was performed on the data from the NavIC/IRNSS receiver. Different ionospheric models were applied to compute ionospheric delay (ionodelay) on a quiet day (3 < K P < 5). Our result shows that both the single-frequency Grid Ionosphere Vertical Error (GIVE) model and dual frequency model outperform remarkably compared to the traditional coefficient-based model. The GIVE model was also analysed on FAR categorized satellites for different stormy days of different months. It was observed that during stormy days also, the 3D position computed by applying the GIVE model was nearly the same as the dual-frequency model.
Richard P Langford - One of the best experts on this subject based on the ideXlab platform.
-
Positional Accuracy of the google earth terrain model derived from stratigraphic unconformities in the big bend region texas usa
Geocarto International, 2011Co-Authors: Christian S Benker, Richard P Langford, Terry L PavlisAbstract:The Google Earth terrain model could prove beneficial for extraction of Positional data in the future. At present, only an aging independent benchmark study (Potere, D., 2008. Horizontal position Accuracy of Google Earth's high-resolution imagery archive. Sensors, 8, 7973–7981) provides constraints on Positional Accuracy for Google Earth imagery. In this investigation, we compared virtually traced positions against high-precision (<1 m) field measurements along three stratigraphic unconformity sub-sections in the Big Bend region to determine current Positional Accuracy for the Google Earth terrain model. A horizontal position Accuracy of 2.64 m RMSEr was determined for the Google Earth terrain model with mean offset distance being 6.95 m. A vertical position Accuracy of 1.63 m RMSEz with mean offset distance of 2.66 m was also calculated for the terrain model. Results suggest data extracted from the Google Earth terrain model could plausibly be used in future studies. However, we urge caution in using Goo...
-
Positional Accuracy of the Google Earth terrain model derived from stratigraphic unconformities in the Big Bend region, Texas, USA
Geocarto International, 2011Co-Authors: S. Christian Benker, Richard P Langford, Terry L PavlisAbstract:The Google Earth terrain model could prove beneficial for extraction of Positional data in the future. At present, only an aging independent benchmark study (Potere, D., 2008. Horizontal position Accuracy of Google Earth's high-resolution imagery archive. Sensors, 8, 7973–7981) provides constraints on Positional Accuracy for Google Earth imagery. In this investigation, we compared virtually traced positions against high-precision (
Christian S Benker - One of the best experts on this subject based on the ideXlab platform.
-
Positional Accuracy of the google earth terrain model derived from stratigraphic unconformities in the big bend region texas usa
Geocarto International, 2011Co-Authors: Christian S Benker, Richard P Langford, Terry L PavlisAbstract:The Google Earth terrain model could prove beneficial for extraction of Positional data in the future. At present, only an aging independent benchmark study (Potere, D., 2008. Horizontal position Accuracy of Google Earth's high-resolution imagery archive. Sensors, 8, 7973–7981) provides constraints on Positional Accuracy for Google Earth imagery. In this investigation, we compared virtually traced positions against high-precision (<1 m) field measurements along three stratigraphic unconformity sub-sections in the Big Bend region to determine current Positional Accuracy for the Google Earth terrain model. A horizontal position Accuracy of 2.64 m RMSEr was determined for the Google Earth terrain model with mean offset distance being 6.95 m. A vertical position Accuracy of 1.63 m RMSEz with mean offset distance of 2.66 m was also calculated for the terrain model. Results suggest data extracted from the Google Earth terrain model could plausibly be used in future studies. However, we urge caution in using Goo...
Paul A. Zandbergen - One of the best experts on this subject based on the ideXlab platform.
-
reference data and geocoding quality examining completeness and Positional Accuracy of street geocoded crime incidents
Policing-an International Journal of Police Strategies & Management, 2013Co-Authors: Timothy C Hart, Paul A. ZandbergenAbstract:Purpose – The purpose of this paper is to examine the influence of reference data, input address quality, and crime type on completeness and Positional Accuracy of street geocoded crime events.Design/methodology/approach – Existing data were analyzed using ArcGIS, including crime incident information, street network reference data, and address point and/or parcel reference data. Geocoding completeness was determined by the overall match rate. Positional Accuracy was determined by comparing the Euclidian distance between street geocoded locations of crime events to the corresponding address point/parcel geocoded location.Findings – Results indicate that match rates vary by reference data, input address quality, and crime type. Local street centerline files consistently produced match rates that were as good as – and in many cases superior to – other types of reference data, including commercial data. Greater variability in Positional Accuracy was observed across reference data when crime type and input add...
-
Positional Accuracy of TIGER 2000 and 2009 Road Networks
Transactions in GIS, 2011Co-Authors: Paul A. Zandbergen, Drew A. Ignizio, Kathryn E. LenzerAbstract:The Topologically Integrated Geographic Encoding and Referencing (TIGER) data are an essential part of the US Census and represent a critical element in the nation’s spatial data infrastructure. TIGER data for the year 2000, however, are of limited Positional Accuracy and were deemed of insufficient quality to support the 2010 Census. In response the US Census Bureau embarked on the MAF/TIGER Accuracy Improvement Project (MTAIP) in an effort to improve the Positional Accuracy of the database, modernize the data processing environment and improve cooperation with partner agencies. Improved TIGER data were released for the entire US just before the 2010 Census. The current study characterizes the Positional Accuracy of the TIGER 2009 data compared with the TIGER 2000 data based on selected road intersections. Three US counties were identified as study areas and in each county 100 urban and 100 rural sample locations were selected. Features in the TIGER 2000 and 2009 data were compared with reference locations derived from high resolution natural color orthoimagery. Results indicate that TIGER 2009 data are much improved in terms of Positional Accuracy compared with the TIGER 2000 data, by at least one order of magnitude across urban and rural areas in all three counties for most Accuracy metrics. TIGER 2009 is consistently more accurate in urban areas compared with rural areas, by a factor of at least two for most Accuracy metrics. Despite the substantial improvement in Positional Accuracy, large Positional errors of greater than 10 m are relatively common in the TIGER 2009 data, in most cases representing remnant segments of minor roads from older versions of the TIGER data. As a result, based on the US Census Bureau’s suggested Accuracy
-
Positional Accuracy of the Wide Area Augmentation System in consumer-grade GPS units
Computers & Geosciences, 2011Co-Authors: Lisa L. Arnold, Paul A. ZandbergenAbstract:Global Positioning System devices are increasingly being used for data collection in many fields. Consumer-grade GPS units without differential correction have a published horizontal Positional Accuracy of approximately 10-15m (average Positional Accuracy). An attractive option for differential correction for these GPS units is the Wide Area Augmentation System (WAAS). Most consumer-grade GPS units on the market are WAAS capable. According to the Federal Aviation Authority (FAA), the WAAS broadcast message provides integrity information about the GPS signal as well as Accuracy improvements, which are reported to improve Accuracy to 3-5m. Limited empirical evidence has been published on the Accuracy of WAAS-enabled GPS compared to autonomous GPS. An empirical study was conducted comparing the horizontal and vertical Accuracy of WAAS-corrected GPS and autonomous GPS under ideal conditions using consumer-grade receivers. Data were collected for 30-min time spans over accurately surveyed control points. Metrics of median, 68th and 95th percentile, Root Mean Squared Error (RMSE), and average Positional Accuracy in the horizontal and vertical dimensions were computed and statistically compared. No statistically significant difference was found between WAAS and autonomous position fixes when using two different consumer-grade units. When using WAAS, a third unit type exhibited a statistically significant improvement in Positional Accuracy. Analysis of data collected for a 27-h time span indicates that while WAAS is altering the estimated position of a point compared to an autonomous position estimate, WAAS augmentation actually appears to decrease the Positional Accuracy.
