INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

1 sec vs 10 sec theodolite

1 sec vs 10 sec theodolite

(OP)
What is the accuracy difference between a 1 second vs a 10 second theodolite. I'll be locating trees on a 1 acre tree farm.

RE: 1 sec vs 10 sec theodolite

Depends on the distance involved.  

1 second at 100 ft is about 0.006 inches

TTFN

Eng-Tips Policies FAQ731-376


RE: 1 sec vs 10 sec theodolite

(OP)
Is there a formula that I can use.1 second at 300 feet is about how many inches?Thanks.

RE: 1 sec vs 10 sec theodolite

The accuracy is approximately the tangent of the angle times the distance.  Call the accuracy "delta", then

Delta=Distance x tan (angle)

For 300 ft, 1 second:

Delta=300 x tan (1 sec/3600)=0.0015 ft = 0.02 inches




RE: 1 sec vs 10 sec theodolite

(OP)
Thanks for the help.Chip

RE: 1 sec vs 10 sec theodolite

For measuring trees, there is no difference in accuracy. Think of it this way - 1 arc-sec = the width of a dime viewed from 1.25 MILES away. So even with 10 arc-sec, you're looking at something the width of 10 dimes, about 5 inches, from 1.25 MILES. So across an acre, you'd be down do the 1/2 dime range or less. And, as usual, your setups and instrument leveling will degrade your readings more than anything.

Oh, and don't forget to use an offset measurement to get the center of tree measurement.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close