This website requires certain cookies to work and uses other cookies to help you have the best experience. By visiting this website, certain cookies have already been set, which you may delete and block. By closing this message or continuing to use our site, you agree to the use of cookies. Visit our updated privacy and cookie policy to learn more.
This Website Uses Cookies
By closing this message or continuing to use our site, you agree to our cookie policy. Learn More
This website requires certain cookies to work and uses other cookies to help you have the best experience. By visiting this website, certain cookies have already been set, which you may delete and block. By closing this message or continuing to use our site, you agree to the use of cookies. Visit our updated privacy and cookie policy to learn more.
Point of Begining Logo
search
cart
facebook twitter linkedin youtube
Point of Begining Logo
  • MAGAZINE
    • Current Issue
    • Digital Edition
    • Classifieds
    • Columns
    • Subscribe
    • POB eNewsletter
  • NEWS
  • PRODUCTS
  • TECH
    • GeoDataPoint
    • LiDAR/Laser Scanning/3D
    • Photogrammetry
    • GIS
    • GPS/GNSS
    • Hardware
    • UAS/UAV
    • Data Collection
    • Remote Sensing
    • Software
    • Total Stations
  • INDUSTRY
    • Aerial
    • BIM
    • Boundary & Topo
    • Construction
    • Energy & Utilities
    • Environmental
    • Forensics
    • Government
    • Marine/Hydrography
    • Mining
    • Transportation
  • REPORTS
    • Laser Scanning & 3D
    • Salary & Benefits
    • Surveying & Mapping Industry Software
    • Surveying & Mapping Industry Equipment
    • 2020 Aerial & UAV
    • Archives & Additional Reports
    • Surveying By State
  • EDUCATION
    • Fundamentals of Surveying
    • Continuing Education
    • GeoLearn
  • ONLINE
    • Events
    • Webinars
    • Classifieds
    • POB Store
    • POB Point and Shoot
    • Photo Galleries
    • Videos
    • Polls
    • FARO Webinars
    • Industry Links
  • DIRECTORY
    • GeoLocator
  • CONTACT
    • Editorial Staff
    • Advertise
    • Clear Seas Research
    • Custom Content Marketing Services
    • List Rental
    • Store
    • Subscription Questions
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Home » Geodetic Surveying Made Plain
Columns

Geodetic Surveying Made Plain

May 22, 2001
Jerry McGray, RPLS
Order Reprints
No Comments

The column about surface adjustment factors (The 900 Lb Gorilla, April 2001) got a few thank-you’s for raising a warning flag. One surveyor, charged with establishing a local coordinate system for a large municipal project, questioned some values he had been given by a GPS contractor. Sure enough, the “scale factors” that were listed beside each point, with no further explanation or metadata, were the grid scale factors alone and did not include the application of the elevation component. It made an important difference. That same column pointed out that the elevation part of a surface adjustment factor should use the height above ellipsoid rather than the orthometric height. In my area, the difference is around 85 feet. It doesn’t make a lot of difference, but I sure don’t want to start out with a 2 or 3 ppm deficit in my error budget, do you? All in all, the responses to the surface adjustment factor were positive.

But the first column (Now Everybody’s Doing It!, January 2001) where we got all poetic about the mystique of round-earth surveying contained a couple of erroneous examples. Sharp-eyed reader John Nolton caught my error when I stated that an 11.5 mile arc on the earth’s surface subtended a chord only 0.05' shorter. John wrote that it should be 0.02' shorter. This time I calculated the chord from scratch (derive curve data for an arc of 60,720 and radius of 20,906,000) and found it to be—yep, 0.02' shorter, which makes an even more dramatic example, of course. Maybe that will teach me to copy “facts” from books without thorough checking. So on that mistake, I got caught understating the example. John’s next red mark came with my talking about lugging a 40-pound T-3 up a mountain. He said the instrument really weighs 24.6 pounds. I don’t know if I got my T-3 stories confused with my T-4 stories or if the weight just grew over the years. But I’ve got to ask this: which sounds more impressive, “lugging a 40-pound ...” or “lugging a 24.6-pound ...”? I rest my case. No, seriously, I appreciate those errors being caught. At this point I should say, “I’ll try to be more careful. So … “I’ll try to be more careful.”

Register today to read the full article! Get unlimited access for free.
Already Registered? Login Privacy Policy

Related Articles

Geodetic Surveying Made Plain

<b>Geodetic Surveying Made Plain</b>

Geodetic Surveying Made Plain

Geodetic Surveying Made Plain

Related Products

Plane and Geodetic Surveying, 2nd edition

GPS Satellite Surveying, 4th Edition

Surveying Instruments and Technology

"The Stadia Crew" Surveying Print, Limited Edition UNFRAMED

Related Directories

Advanced Geodetic Surveys Inc.

Subscription Center
  • Subscribe
  • Free eNewsletters
  • Customer Care

More Videos

Popular Stories

Antique Land Surveyors Transit

Antique Land Surveyors Transit to Hit Auction

Policy Points column default 2021

President Biden’s Infrastructure Plan Has Something for Land Surveyors

surveying licensure exam

How I Passed the Fundamentals of Surveying Exam

stooped oak

Land Surveyor Finds ‘Stooped Oak’ in Webbville, Kentucky

The Benefits of Diversity In the Geospatial Profession

Women In GIS: The Benefits of Diversity In the Geospatial Profession

FARO webinar series

Events

December 1, 2030

Webinar Sponsorship Information

For webinar sponsorship information, visit www.bnpevents.com/webinars or email webinars@bnpmedia.com.

View All Submit An Event

Poll

Women in Surveying

Does land surveying need more women in leadership?
View Results Poll Archive

Products

2020 Point of Beginning Aerial & UAV Research

2020 Point of Beginning Aerial & UAV Research

See More Products

Get the POB Point delivered to your inbox!

Stay in the know on the latest surveying and geospatial trends.

SUBSCRIBE NOW
  • Resources
    • Construction Group
    • List rental
    • Survey And Sample
    • Associations & Industry Links
    • Subscribe
    • Editorial Calendar
    • Editorial Guidelines
    • Order Reprints
    • Want More
    • Connect
    • Contact Us
  • Advertise With Us
    • Advertise
  • Subscribe
    • Subscribe
    • Free eNewsletters
    • Customer Care
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2021. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing