Angular Measurements And Angle Measurıng Instruments (Tacheometers And Theodolites)

CE200 SURVEYING

Associate Professor Dr. Haluk ÖZENER

Istanbul Technical University Faculty of Civil Engineering Geomatics Engineering Department

phone: 0212 2853819

e-mail: ozener@boun.edu.tr

http://www.koeri.boun.edu.tr/jeodezi

Angles & Directions

An angle is defined as the difference in direction between two convergent lines.

A horizontal angle is formed by the directions to two objects in a horizontal plane.

A vertical angle is formed by two intersecting lines in a vertical plane, one of these lines horizontal.

A zenith angle is the complementary angle to the vertical angle and is formed by two intersecting lines in a vertical plane, one of these lines directed toward the zenith.

Angles & Directions

• Gometric Definition of AnglesA

P

B

Horizontal Angle

Vertical Angle

Angles & Directions

Vertical Angles

Tacheometers & Theodolites

Angle instruments called tacheometers or theodolites, depending on their precision in measuring angles.

EyepieceFocus(For cross hairs)

InternalFocus(For sightingobject)

Telescope clamp(up / down)

Upperplate clamp(left / right)

Slow motiontanget screw(up / down)

Slow motiontanget screw(left / right)

Axes of Theodolite

Theodolite

Theodolite

Setting up the TheodolitePlate Level Bubble Tube

Foot Screws

The bubble should be moved to the rightBubble follows direction of left thumb

Both thumbs move in (or out)

Setting up the Theodolite

Recommendations• Fine level the theodolite using the PLATE level bubble tube and foot

SCREWS

• Position a) align the plate level bubble tube with two foot screws. – Centre the bubble by rotating the two foot screws in

opposite directions. – The bubble follows the LEFT thumb.

• Position b) align the plate level bubble tube with the third foot screw.

– Centre the bubble by rotating the the third foot screw (only). The bubble follows the LEFT thumb.

Setting up the Theodolite

Position a

Bubble Follows Left Thumb

Position a Position b900 to position a

Bubble Still Follows Left Thumb

Summary Of Errors In Angle & Direction Measurements

Summary Of Errors In Angle & Direction Measurements

Summary Of Errors In Angle & Direction Measurements

Common Mistakes

Point or Target misidentificationsIncorrect recordingsImproper focusing

Officework 1

Officework 1