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Managing GPS Error: Tips for Better Maps and Communication

Learn how to manage GPS errors, improve map accuracy, and enhance communication with this comprehensive guide. Explore the importance of datums, error, accuracy, and precision, and discover tips for minimizing errors in GPS mapping.

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Managing GPS Error: Tips for Better Maps and Communication

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  1. GPS CommunicationSoftware GPS Mapping Program Tarpits and Tips Tarpits and Tips Tools of the Trade

  2. Tools of the Trade - Part IV Tarpits and Tips TIPS

  3. Outline • Datums • Error, Accuracy, and Precision • Map Scale and Errors • Tips for Managing GPS Error • Better Maps for GPS

  4. GPS Datum Tarpit • What’s the big deal • A football field of difference if you are wrong! • Ask the 3 soldiers in Afghanistan

  5. If you were in Alaska Datum Shift 90 feet Florida Example

  6. GPS Datum Tarpit • Summary: • Know your Datum at all times • When you hear WGS84, it’s the same as NAD83 Aviation GPS is always WGS84

  7. Error, Accuracy, and Precision • Importance • Safety • Make or break a GIS project • Learn ways to keep GPS errors to a minimum • Be aware of the issues Kenneth E. Foote and Donald J. Huebner, The Geographer's Craft Project, Department of Geography, The University of Colorado at Boulder.

  8. Basic Definitions 1.) Accuracy: how close to truth or accepted values. 2) Precision: how repeatable or consistent

  9. Basic Definitions 3.) Error: includes both the imprecision of data and its inaccuracies Accurate + Precise = Low Error !

  10. False Advertising • Beware of False Accuracy and False Precision • UTM = 1 meter • DMS.S = Translates to about 3 meters

  11. Map Scale • Accuracy and Precision for a map are a function of the scale at which the map was created • Applies for digital or paper • National Mapping Accuracy Standards employed by USGS

  12. Accuracy Standards for Various Map Scales • 1:2,400 ± 6.67 feet • 1:24,000 ± 40.00 feet • 1:63,360 ± 105.60 feet • 1:100,000 ± 166.67 feet

  13. 1:2,400 R=6.67’ 1:12,000 R=33.33’ 1:24,000 R=40’ Map Scale

  14. Map Scale - Points

  15. Map Scale - Lines

  16. Map Scale and the Garmin • Question? Will your Garmin III Plus meet Mapping Accuracy standards for a 1:24,000 scale product? • How about a 1:63,360? • Today, we will answer that question?

  17. Sources of Map Errors • Age of Data • Map Scale Mapsource data is 1:100,000 scale • Digitizing Errors

  18. Tips for Managing GPS Error • Record Metadata: • Who, What, Why

  19. Managing GPS Error • Try to average points

  20. Managing GPS Error • Try to use Antenna when possible

  21. Make Better Maps for GPS • Basic Premise: • Maps and GPS are made for each other • Location finding requires map grids, labeled tics and graticules • Ingredients Required: • ArcView • Coordinate Grid Maker extension* • Map Data *Christoph Feldkotter Version 2.270 Available from www.esri.com/arcscripts

  22. Summary • Importance of Datums • How error free are you? • By managing error you can beat the odds

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