ArcGIS Data Reviewer: Assessing Positional Accuracy. Roslyn Dunn

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1 ArcGIS Data Reviewer: Assessing Positional Accuracy Roslyn Dunn

2 What is ArcGIS Data Reviewer? Data Quality Management for ArcGIS Provides - Rule-based validation - Interactive tools - Track errors Validate For individuals and enterprise - Saves time/money - Less rework Enterprise Workflow For multiple domains - Configurable - Extendable Summarize Review

3 What is ArcGIS Data Reviewer? Data quality management in the ArcGIS platform Data Reviewer for Desktop - ArcMap - ArcGIS Pro Desktop Web Device Data Reviewer for Server - Standard or higher ArcGIS Online Portal Data Reviewer API - JavaScript - FLEX Server Web AppBuilder for ArcGIS Online Content and Services

4 Forms of Geospatial Data Accuracy Spatial (position, geometry, topology) Attributional (correctness of attributes) Spectral (band depth) Temporal (appropriate date) Radiometric (capture piece of electromagnetic spectrum)

5 Concepts Data needs to be in the right place for intended purpose - Usually scale-dependent to some degree All else being equal, less accurate is less valuable Data products usually need to conform to a specification - ASPRS Positional Accuracy Standards November Orthoimagery - Digital Planimetric Data - Digital Elevation Data DMA - Error Theory as Applied to Mapping, Charting, and Geodesy

6 Definition of Terms Accuracy - The closeness of the best estimated value obtained by the measurements to the true value of the quantity measured - How well does the measured quantity compare to the true value? Positional Accuracy - The Quantifiable value that represents the positional difference between two geospatial layers or between a geospatial layer and reality Circular Error (CE) is an error measurement for both X & Y Linear Error (LE) is generally an error measurement for Z (elevation) RMSE is a statistical measurement of the variance between the residual values

7 Definition of Terms Circular Error a two-dimensional error measure (X, Y) CE 90, 95, 99 - The radial error which n% of all errors in a circular distribution will not exceed - Circular error at n% confidence level - e.g. If CE 90 = 2.0 Meters then we are 90% confident that the measurement lies somewhere within a circle with a radius of 2.0 Meters i.e. we re 90% sure the error won t be more than 2.0 Meters

8 Definition of Terms Linear Error a one-dimensional error measure (z) - A measure of the vertical accuracy of the terrain (e.g. DEM or TIN) The difference between the true or known value and the measured or derived value LE 90, 95, 99 - Linear error at n% confidence level - e.g. If LE 95 = 10 Meters then we are 95% confident that the true elevation measurement is within 10 Meters ELEVATION (M)

9 Positional Accuracy Assessment Tool (PAAT) PAAT Tool - Part of GIS Data Reviewer Created with requirements gathered from NGA Determine accuracy of - Imagery - Rasters - Vectors

10 Positional Accuracy Assessment Tool (PAAT) Reporting NGA standard or USGS standard CE 90, 95, 99 LE 90, 95, 99 (for DEMs or TINs) RMSE Absolute or relative

11 Positional Accuracy Assessment Tool (PAAT) Outputs Text report Optional outputs: - Accuracy attribute populated (if assessing vectors) - XML Metadata - ISO - PMAA (NGA) - Shapefile of point reading locations

12 Positional Accuracy Assessment Tool (PAAT) DEMO

13 Positional Accuracy Assessment Tool (PAAT) Statistical Sampling Time is money Sampling saves time Statistical sampling tool answers the question: Given a population size, what sample size do I need to be X percent confident that the sample size is statistically significant, within Y percent margin of error?

14 Want to learn more? Product information

15 Want to learn more? Documentation - Desktop - Server Training (training.esri.com) - Assessing Data Quality using ArcGIS Data Reviewer (Seminar) - Evaluating Positional Accuracy Using ArcGIS Data Reviewer for Desktop (Seminar) - Data QC with ArcGIS: Automating Validation (Web Course) - Data QC with ArcGIS: Visual Review (Web Course) - Quality Control Using ArcGIS Data Reviewer for Desktop (Instructor-Led)

16 Want to learn more this week? Tuesday June 28 ArcGIS Data Reviewer: Day and Description Type Time Location An Introduction Technical Workshop Demo Theater 10:30 11:15am ArcGIS Data Reviewer: Integrating ArcGIS Data Reviewer and ArcGIS Workflow Manager to Automate Data Quality Control Workflows ArcGIS Data Reviewer: Leveraging Geoprocessing for Data Validation ArcGIS Data Reviewer: Quality Assessment for Elevation Raster Datasets Wednesday June 29 ArcGIS Data Reviewer: Thursday June 30 ArcGIS Data Reviewer: ArcGIS Data Reviewer: ArcGIS Data Reviewer: An Introduction Advanced Data Validation Concepts Implementing Data Quality Reporting in Web Clients Integrating Data Validation Capabilities into Web Applications Demo Theater Demo Theater Demo Theater Technical Workshop Technical Workshop Demo Theater Demo Theater 8:30 9:45am Room 15B 11:30 12:15pm 12:30 1:15pm 2:30 3:15pm 3:15 4:30pm Demo Theater 4 Geodata Demo Theater 4 Geodata Demo Theater 4 Geodata Demo Theater 4 Geodata Sapphire Ballroom A/B 8:30 9:45am Room 32 A/B 10:30 11:15am 12:30 1:15pm Demo Theater 6 Server Demo Theater 6 Server

17 Thank you Please fill out the session survey using the Esri Events mobile app Select ArcGIS Data Reviewer: Assessing Positional Accuracy session - Use the Search Feature to quickly find this title Scroll-down to the Feedback section Answer a few short questions, enter any comments and select Submit!

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