Considering the options for taking Direct and Reverse measurements between two points (the backsight and foresight). The four options are:
1. BD-FD/FR-BR
2. BD-BR/FD-FR
3. BD-FD/BR-FR
4. BD-BR/FR-FD
First, I assume there's absolutely no difference in the results of taking the measurements in any of these orders.
Beyond that, is it completely personal preference?
Thinking about it, There seems to be a time advantage to 2. and 4. in that you don't have to step around the instrument as much. And of those two, 4. seems marginally more efficient in that you can swing the gun to the FS without flipping it; then flipping for the last measurement.
Are there other factors (besides efficiency in taking the shots), upon downloading the data for example, that should be considered? Or is this just one of those things that you do the way you do it because you've always done it that way?
I use routine 1 as a matter of personal preference. I don't think it makes a difference as far as proper procedure is concerned, but others may disagree. I am using a robotic instrument, so walking around is not much of an issue.
Use option 4 if you're working solo robotically
I prefer option 4 for the reasons you stated. Options 2 & 4 also allow you to shoot the backsite before the foresite is completely set.
Ralph nailed the robotic one for minimal travel.
In the past, I always used number 1 to close the horizon. It made sense to add another check on 360 totals.
But, technology probably makes that pointless.
An aside - for those who know what a pointing is, pun intended.;-)
If your running solo on a bot you can't beat number 4.
> I prefer option 4 for the reasons you stated. Options 2 & 4 also allow you to shoot the backsite before the foresite is completely set.
Thanks. Hadn't thought of that.
I should have noted that the question was in the context of NON ROBOTIC operation. I can definitely see where 1. or 3. would be pretty crazy (unless one is doing this instead of going to the gym).:-)
If you are doing more than one set, all but #3 are pretty much the same.
BD/FD-FR/BR--BR/FR-FD/BR That is a Set
BD/FD-FR/BR is a single observation.
Paul in PA
You are right it is a matter of personal preference. I use option 3 because I run non robotic and ghost everything into the field book in horizontal distance on all observations. This option allows crews to write in the book with out jumping around.
BS 1
INST 2
3 DR 0-00-00 123.45
DF 321-45-40 118.32
AVG 321-45-38 118.31
RB 179-59-58 -123.44
RF 141-45-34 -118.30
diff [321-45-36]
But as I said earlier this is just the preference we have come up with in our office.
Option 1 while running conventional total station. I always seem to get higher precision that way....option 4 for solo robotic for obvious reasons.
If you are running a manual theadolite the method needs to promote use of a greater portion or variation of the circle. Not so much with robots and total stations these days...