Nothing wrong with using a lath or nail in a branch for a backsight.
There is some skill to setting a stable lath backsight. I have set double lath backsights on top of ridges that have maintained plumb for several weeks, even with the wind blowing.
That would be a 4' lath strapped to the one pounded in the ground.
I can draw you a pic, of how to do it, with a COT. (Cut off Tree).
N
I've still got 2 good locus.
Nate The Surveyor, post: 399201, member: 291 wrote: I can draw you a pic, of how to do it, with a COT. (Cut off Tree).
N
Nate: I'm not sure how we got off the original topic and onto back sights, but I'm just as good with that too. I tried to find another lengthy thread on nearly the same subject (ad hoc backsights using cut off trees, nails in poles etc.), and remember what the problem is: With SurvCE, there is no way to observe and "book" into the DC, an observation that is angle only. Yes, for a back sight, you can set the backsight angle to zero, but you need to know where that backsight is to do anything with it.
When doing my astro, for example, I used a distant mark as a back sight (one I had no access to), but those angles were all manually read and booked old school.
My network of triangles/quads consists of points, whose locations have been determined from previously surveyed points. I know I could always manually create a backsight to a tree/nail etc. at the end of a session, so that when setup again on my latest point, it would save setting up a prism on a previous point, but for what I'm doing, that's not a real savings in time, as I invariably need to shoot that previous point from several other new points anyway.
This may be an issue only for me, or only because I'm using SurvCE; other software may have the capability; but I'm just working with what I got.
rfc, post: 399235, member: 8882 wrote: Nate: I'm not sure how we got off the original topic and onto back sights, but I'm just as good with that too. I tried to find another lengthy thread on nearly the same subject (ad hoc backsights using cut off trees, nails in poles etc.), and remember what the problem is: With SurvCE, there is no way to observe and "book" into the DC, an observation that is angle only. Yes, for a back sight, you can set the backsight angle to zero, but you need to know where that backsight is to do anything with it.
When doing my astro, for example, I used a distant mark as a back sight (one I had no access to), but those angles were all manually read and booked old school.
My network of triangles/quads consists of points, whose locations have been determined from previously surveyed points. I know I could always manually create a backsight to a tree/nail etc. at the end of a session, so that when setup again on my latest point, it would save setting up a prism on a previous point, but for what I'm doing, that's not a real savings in time, as I invariably need to shoot that previous point from several other new points anyway.This may be an issue only for me, or only because I'm using SurvCE; other software may have the capability; but I'm just working with what I got.
You might want to set your backsight as an azimuth or bearing.
Paul in PA
Paul in PA, post: 399242, member: 236 wrote: You might want to set your backsight as an azimuth or bearing.
Paul in PA
I don't think you understand the issue. I can't use a back sight when returning to a previous point unless the azimuth of that backsight has been previously determined. it can't be previously determined in SurvCE without a prism on it. You can't specify "azimuth only" either in "Store Points", "Collect Sets", or any other option that I've found. There's no problem using "azimuth" in the back sight screen, once you know where the back sight is.
With a pinch of DOT tape, (which converts an innocuous nail, into a prism) we now have distance.
Nate The Surveyor, post: 399253, member: 291 wrote: With a pinch of DOT tape, (which converts an innocuous nail, into a prism) we now have distance.
DUH!:cool: Got it! Thank you, Sir.
rfc, post: 399247, member: 8882 wrote: I don't think you understand the issue. I can't use a back sight when returning to a previous point unless the azimuth of that backsight has been previously determined. it can't be previously determined in SurvCE without a prism on it. You can't specify "azimuth only" either in "Store Points", "Collect Sets", or any other option that I've found. There's no problem using "azimuth" in the back sight screen, once you know where the back sight is.
Other than your first setup on a job, where you might assume an azimuth for a backsight, all backsights are to known points. If it is not a known point, it is not a backsight.
I use SMI and it allows me to store angle only shots, but if I look at my raw data every angle only shot will have a distance of 123.456 which jumps off the page or screen as an indicator. I can also take a second angle only shot from another traverse point and it will calculate the intersection coordinates. If there is not button for this in SurvCE you can always do it manually. As I said do not estimate a distance, use 123.456'.
Years ago I did about a 20 acre survey that had a wind generator tower. I shot that from 9 traverse points D&R. After closing my traverse within 0.01', I calculated the intersection point. All azimuths ended inside an 0.02' radius circle on that coordinate. I used that tower as backsight from several traverse points when I went back to set corners.
Paul in PA
Nate The Surveyor, post: 399253, member: 291 wrote: With a pinch of DOT tape, (which converts an innocuous nail, into a prism) we now have distance.
That worked perfectly! I used "Store Points" to do it. Now I have a back sight! Thank you.
Check your dist with a box tape, (do a shot 10' away) your offsets may be off a little.
Just to keep track of what you are doing.