Georeferencing Best Practices Arthur D. Chapman, John R. Wieczorek Version 3e04c5b, 2020-12-30 13:27:44 UTC Table of Contents Colophon. 1 Suggested citation. 1 Authors . 1 Contributors . 1 Licence . 1 Persistent URI . 1 Abstract. 1 Document control . 1 Disclaimer . 1 Cover image . 2 1. Introduction . 2 1.1. Objectives . 3 1.2. Target Audience . 4 1.3. Scope . 4 1.4. Constraints . 5 1.5. Principles of Best Practice. 5 1.6. Accuracy, Error, Bias, Precision, False Precision, and Uncertainty . 6 1.7. Software and Online Tools . 8 1.8. Conformance to Standards . 8 1.9. Persistent Identifiers (PIDs) . 8 2. Elements for Describing a Location . 9 2.1. The Importance of Good Locality Data. 9 2.2. Localities . 10 2.3. Extent of a Location. 11 2.3.1. Transects . 12 2.3.2. Paths. 12 2.3.3. Polygons . 13 2.3.4. Grids . 14 2.3.5. Three-Dimensional Shapes . 15 2.4. Coordinates. 16 2.4.1. Geographic Coordinates . 16 2.4.2. Universal Transverse Mercator (UTM) Coordinates . 17 2.5. Coordinate Reference System . 18 2.6. Using a GPS. 19 2.6.1. Choosing a GPS or GNSS Receiver . 20 2.6.2. GPS Accuracy. 20 2.6.3. Differential GNSS . 20 2.6.4. Satellite Based Augmentation System . 21 2.6.5. Ground-based Augmentation System. 22 2.6.6. Precise Point Positioning. 22 2.6.7. Static GPS. 23 2.6.8. Dual and Multi-Frequency GPS. 23 2.6.9. Smartphones. 23 2.6.10. GPS-enabled Cameras . 23 2.6.11. Diver-towed Underwater GPS Receivers. 24 2.7. Elevation . 24 2.7.1. Altimeters . 24 2.7.2. Maps. 25 2.7.3. GPS . 25 2.7.4. Vertical Datums . 25 2.7.5. Digital Elevation Models . 26 2.7.6. Smartphones. 26 2.7.7. GPS-enabled Digital Cameras. 27 2.7.8. Google Earth.