Precision GPS Videos

General Videos

Even if you are an experienced GIS, Mapping or Survey user you may have some questions about the realities of precision GPS real-world use:

  • Grid vs. Ground Measurements
  • U.S. Survey Feet vs. International Feet
  • Reference Frames vs. Datum: WGS84, NAD83, NAD83-CORS96, NAD83-2011, ITRF2000...
  • Best Practices for Collecting Data in the Field
  • Ellipsoid vs. Orthometric Elevations: Hey! My GPS always reads elevations that are 100 feet off

These videos may help you sort out these questions. Here is a recommended viewing list:

#1 Thumbnail U.S. Survey Feet vs. International Feet

  0.3048 vs. 0.30480061 what is the difference?

#2 Thumbnail Grid vs. Ground Distance Measurements

  Why does my GPS measure distances short?

#3 Thumbnail Ellipsoid vs. Orthometric Elevations

  Why is the elevation on my GPS receiver off 70 feet?

#4 Thumbnail Best Practices for Maximizing GPS Accuracy

  How do you hold your receiver while collecting data to maximize accuracy?

#5 Thumbnail OPUS Projects Example

Matches the American Surveyor Article found [ here ]

#9 What is Sea Level?