This question isn't necessarily for surveying, but more so for point layout using a robotic total station using local coordinate system vs global (i.e. state plane).
When I set up total station on an unknown random point, i.e. 1000,1000,100 local coordinate system, I then need to shoot to the backsight to set my orientation reference.
Is there a best practice when choosing a backsight point? I know I can just place it anywhere.
Is it maybe best to set the backsight point direct TRUE geographic North in relation to the total station at the start, and so north is up in my layout software etc?
Or in the case of a known point, do you set up on a known point, (i.e. property corners) then set backsight on another known point (property corner)... I guess you could use that line as a bearing basis, then ZERO the total station azimuth to NORTH that way?
After I set my total station point and the backsight point (or direction to zero north), I then import and transform my layout points to where I need them. I.e. center control point, then I rotate them relative to north depending on direction I need them.
I guess using GNSS, north is always up in the layout software, so not as trivial. But setting the total station azimuth to zero north before I start is where I am not sure. Seems I should set the backsight to north from the start to get everything straight up?
Thanks for the help guys.
Me, I prefer to be working in the same terms as the underlying plan as soon as I can.
Rotating and translating afterwards is a P.i.t.A.
There are a number of ways to achieve this, and in part it depends on how good the plans are, and what information they show
One possibility is to setup on a known point, sight an other known point and key-in the Azimuth you want that line to be.
Or free-station yourself off two (or better three) points from your plan.
If you have a gnss, you can set three or four points and use them for a free-station.
In all cases you want to have a couple of checks to ensure you are getting the numbers you expect
There is no advantage to having your backsight point being true north from your setup point. It is only necessary that you know what the bearing to the backsight point is, so that the angle to north - or any other point on the compass - may be calculated.
Sometimes you "know" the bearing to your backsight because you have assigned a value to it simply by guessing. This is known as a "assumed basis of bearings". A great many surveys are started this way, then later rotated to a known bearing when some points that are tied can be related to some record that reports a bearing.
For layout, in my experience it's more about which orientation is easier to work with in the DC for whatever part of the site we are working on.
We run Trimble Access, so we can set the reference azimuth to whatever we want after completing our station setup.
In your scenario the best practice is the one that works with the way you think. Now don’t screw it up. Lol
I don't understand the fixation with North. If you have a control network with known values, calibrate your construction drawings to your own coordinates and call it a day.
I don't understand the fixation with North. If you have a control network with known values, calibrate your construction drawings to your own coordinates and call it a day.
The "fixation" on north is because at the start of my question:
"This question isn't necessarily for surveying, but more so for point layout"
I have points that must be orientated correctly in reference to NORTH (especially when I may not have any sort of surrounding control points to lock to in the design or the site except for say a 1 point center for control (and rotation from that once localized to it)...therefore my "fixation" on north. This is straight forward using GNSS, north always up...just wondering what the proper procedure is or used when using a total station since as mentioned by others, the total station is DUMB and doesn't know where north is.
My work doesn't involve necessarily always having some sort of bearing basis like a survey drawing or record to calculate from and traverse from there. So referencing true geographic north (same as GNSS, not magnetic or otherwise) is what needs to be used... in my special cases. I am not always using GNSS, but total station due to limited sky view conditions sometimes.
Thank you
It you have a point with a known bearing/azimuth from your TS setup point, then you can turn angles with respect to that, whether that known azimuth is 0 degree or 27° 53' 12" or any other value. Just compute those angles.
Just read your last post that provided further clarification of what you want to do. YouTube is a great resource for non-surveyors. Good luck.
YouTube is a great resource for non-surveyors. Good luck.
Most everything is in indian.. If not, a lot left to be desired or not enough detailed information.
: /
I figured it out. Thanks for the help.
You could try using a compass and entering the azimuth when shooting the backsight then the total station and control will match that rotation which would be close to north. Also, I just like to be rotated north to make matching aerial overlays easier.
