Positional Accuracy Analysis of Satellite Imagery by Circular Statistics

2010 ◽  
Vol 76 (11) ◽  
pp. 1275-1286 ◽  
Author(s):  
A. Cuartero ◽  
A.M. Felicísimo ◽  
M.E. Polo ◽  
A. Caro ◽  
P.G. Rodríguez
Keyword(s):  
Satellite Imagery ◽  
Circular Statistics ◽  
Accuracy Analysis ◽  
Positional Accuracy

scholarly journals Position Accuracy Analysis on Disc Storing Mechanism for Benthic Drill

2014 ◽  
Vol 8 (1) ◽  
pp. 382-386
Author(s):  
Y. Guo ◽  
Y. P. Jin ◽  
M. Jiang ◽  
B. W. Luo
Keyword(s):  
Analytical Formula ◽  
Mathematic Model ◽  
Hydraulic Cylinder ◽  
Positional Error ◽  
Accuracy Analysis ◽  
Positional Accuracy ◽  
Positional Analysis ◽  
Cylinder Length ◽  
Dimensional Parameters ◽  
Nonlinear Iteration

The positional accuracy of disc storing mechanism for benthic drill is the guarantee of long hole coring in deep sea. Aiming the lack of positional accuracy analysis on disc storing mechanism, the mathematic model of the positional accuracy for disc storing mechanism is presented by using complex vector and matrix analyzing method. The analytical formula of crank rotation positional accuracy is acquired through rotation positional analysis of crank in disc storing mechanism driven by hydraulic cylinder. Adopting numerical nonlinear iteration solution method of Newton-Simpson, the variation rule of rotation positional error for disc storing mechanism to cylinder length is acquired, which supports an important theory, leading to tolerance design for dimensional parameters of disc storing mechanism.

scholarly journals The Typhoid Fever Surveillance in Africa Program: Geospatial Sampling Frames for Household-based Studies: Lessons Learned From a Multicountry Surveillance Network in Senegal, South Africa, and Sudan

2019 ◽  
Vol 69 (Supplement_6) ◽  
pp. S474-S482
Author(s):  
Stephen Baker ◽  
Mohammad Ali ◽  
Jessica Fung Deerin ◽  
Muna Ahmed Eltayeb ◽  
Ligia Maria Cruz Espinoza ◽  
...  
Keyword(s):  
South Africa ◽  
Satellite Imagery ◽  
Population Based ◽  
Google Earth ◽  
Lessons Learned ◽  
Data Availability ◽  
Sampling Frame ◽  
Positional Accuracy ◽  
Surveillance Network ◽  
Mean Square Errors

Abstract Background Robust household sampling, commonly applied for population-based investigations, requires sampling frames or household lists to minimize selection bias. We have applied Google Earth Pro satellite imagery to constitute structure-based sampling frames at sites in Pikine, Senegal; Pietermaritzburg, South Africa; and Wad-Medani, Sudan. Here we present our experiences in using this approach and findings from assessing its applicability by determining positional accuracy. Methods Printouts of satellite imagery combined with Global Positioning System receivers were used to locate and to verify the locations of sample structures (simple random selection; weighted-stratified sampling). Positional accuracy was assessed by study site and administrative subareas by calculating normalized distances (meters) between coordinates taken from the sampling frame and on the ground using receivers. A higher accuracy in conjunction with smaller distances was assumed. Kruskal-Wallis and Dunn multiple pairwise comparisons were performed to evaluate positional accuracy by setting and by individual surveyor in Pietermaritzburg. Results The median normalized distances and interquartile ranges were 0.05 and 0.03–0.08 in Pikine, 0.09 and 0.05–0.19 in Pietermaritzburg, and 0.05 and 0.00–0.10 in Wad-Medani, respectively. Root mean square errors were 0.08 in Pikine, 0.42 in Pietermaritzburg, and 0.17 in Wad-Medani. Kruskal-Wallis and Dunn comparisons indicated significant differences by low- and high-density setting and interviewers who performed the presented approach with high accuracy compared to interviewers with poor accuracy. Conclusions The geospatial approach presented minimizes systematic errors and increases robustness and representativeness of a sample. However, the findings imply that this approach may not be applicable at all sites and settings; its success also depends on skills of surveyors working with aerial data. Methodological modifications are required, especially for resource-challenged sites that may be affected by constraints in data availability and area size.

Accuracy assessment and performance analysis of raster to vector conversions on LULC data – India

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Prafullata Kiran Auradkar ◽  
Atharva Raykar ◽  
Ishitha Agarwal ◽  
Dinkar Sitaram ◽  
Manavalan R.
Keyword(s):  
Open Source ◽  
Real World ◽  
Spatial Data ◽  
Complexity Analysis ◽  
Accuracy Analysis ◽  
Positional Accuracy ◽  
Raster Data ◽  
Content Type ◽  
System Resource ◽  
Shape Complexity

Purpose The purpose of this paper is to convert real-world raster data into vector format and evaluate loss of accuracy in the conversion process. Open-source Geographic Information System (GIS) is used in this process and system resource utilizations were measured for conversion and accuracy analysis methods. Shape complexity attributes were analyzed in co-relation to the observed conversion errors. Design/methodology/approach The paper empirically evaluated the challenges and overheads involved in the format conversion algorithms available in open-source GIS with real-world land use and land cover (LULC) map data of India. Across the different LULC categories, geometric errors of varying density were observed in Quantum GIS (QGIS) algorithm. Area extents of original raster data were compared to the vector forms and the shape attributes such as average number of vertices and shape irregularity were evaluated to explore the possible correlation. Findings The results indicate that Geographic Resources Analysis Support System provides near error-free conversion algorithm. At the same time, the overall time taken for the conversion and the system resource utilizations were optimum as compared to the QGIS algorithm. Higher vector file sizes were generalized and accuracy loss was tested. Research limitations/implications Complete shape complexity analysis could not be achieved, as the weight factor for the irregularity of the shapes is to be varied based on the demography as well as on the LULC category. Practical implications Because of the higher system resource requirements of topological checker tool, positional accuracy checks for the converted objects could not be completed. Originality/value This paper addresses the need of accuracy analysis of real-world spatial data conversions from raster to vector format along with experimental setups challenges and impact of shape complexity.

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