# THREE-DIMENSIONAL ADJUSTMENT.pptx - Lecture 5 TOTAL STATION...

• 29

This preview shows page 1 - 7 out of 29 pages.

Lecture 5 TOTAL STATION ADJUSTMENT 1 of 25
A B D C A three-dimensional traverse is a figure that is created from total station field measurements, as for the parcel to the right. Since this is an effort that involves some error, its adjustment is normally necessary, unless the error is negligible (say, 0.02’ times the number of stations) for the purpose. If the error is large (say, 0.10’), the measurement must be redone. A parcel defined by a traverse 2 of 25
A B D C The adjustment of a three- dimensional traverse involves the correction of small horizontal and vertical errors of three quantities of each leg: 1. Leg direction 2. Leg length 3. Point elevation. Note that horizontal and vertical adjustments are done separately. First, we will deal with the horizontal one (X,Y). A parcel defined by a traverse 3 of 25
For starters, it will be necessary to know something about the traverse: 1. The horizontal coordinates of one of its points (say point A) 2. The elevation of that start point A 3. The direction to another known point (say line A-P) For this example: EA, NA = 1,000.00, 1,000.00 ZA = 1,000.00 BEARING AP = N 50° 15’ 45” W* *meaning that line AP has that angle from North, toward the West Known information 4 of 25 A (1000.00, 1000.00, 1000.00) B D C P N 50 ° 15’ 45” W
First, we convert the bearing into an “azimuth” because it is much easier to work with. The azimuth, or the direction of the line AP is: AzAP = 360 ° - Brg AP = 309.7375 ° The red arrow is added to indicate direction Preparation 5 of 25 P AzAP=309.7375 ° North A B D C
We set the total station up on point A. We place the reflector on point P. We aim the instrument at the reflector, and we press the measurement button to get: Slope distance SD-AP Direction* D-AP (say: 89.8745 ° ) Vertical angle v-AP (Of this, we will use only D-AP for now) * Any number from 0 to 360 that the instrument wakes up with, since it does not know where North is.