Looks like you're traversing in a clockwise direction. If so, and turning angles right, then the theoretical sum of the EXTERIOR angles would be (n+2)*180.
SS
Kent McMillan, questions for you
> 1. Due to topography of the land I had to have so many short legs. However, if I create a line of sight between Pt. 22 and 29 do you think I will give worthwhile angular closure? It is a fairly thick wall of Banyan (Ficus Benjamina) but doable.
Any cross ties you could generate to reduce the number of legs in each closed figure would be beneficial. In this case isolating those short legs 22-29 especially so. Depending on the work involved you may benefit almost as much by rerunning the traverse 22-29.
> 2. You implied in the note there is another method of centering that might improve the angular misclosure. I used prism poles instead of tripods for my back sight and foresight--as I was not confident that I'll measure the vertical accurately.
Targets on tripods have smaller centering errors than rods. Among the several reasons is that the level bubble on a tribrach is more sensitive than those on rods. This assumes, of course, is that both are in adjustment.
Best file format/converter for Starnet
> I don't have a version beyond Ver.6, but I understand that the converters from various DC formats are built into the later releases. You don't have to purchase them as separate programs as Ver.6 users do.
They (the terrestrial data converters) are "built in" but you have to purchase the access code to activate each one separately all the same. The GNSS data converters are all available with the pro version just as always.
Kent McMillan, questions for you
Aloha, Mark:
Thank you so much for your suggestion and thought!
I have both regularly checked for adjustment and adjusted as necessary. I have the Seco calibration gizmos.
I know you and several others have mentioned this in the past, I can simply add 0.01ft as long as the tripod setup is around 5ft--to convert slant height. But I also can do quick trig. calculation as I go. Perhaps, it is time for me to practice and perfect this method instead of using prism poles for control network creation.
Thank you and aloha!
> Any cross ties you could generate to reduce the number of legs in each closed figure would be beneficial. In this case isolating those short legs 22-29 especially so. Depending on the work involved you may benefit almost as much by rerunning the traverse 22-29.
>
> Targets on tripods have smaller centering errors than rods. Among the several reasons is that the level bubble on a tribrach is more sensitive than those on rods. This assumes, of course, is that both are in adjustment.
Kent McMillan, questions for you
>.... I can simply add 0.01ft as long as the tripod setup is around 5ft--to convert slant height. ..
Probably you mean to deduct 0.01' from your slant measurement to get the vertical height. And I like to use a 6' folding ruler, graduated in engineers units, to make the measurement. Although most will use a 25' box tape with no particular issues.
Kent McMillan, questions for you
Aloha, Norman:
Correct!
Thanks
> Probably you mean to deduct 0.01' from your slant measurement to get the vertical height. And I like to use a 6' folding ruler, graduated in engineers units, to make the measurement. Although most will use a 25' box tape with no particular issues.
Kent McMillan, questions for you
> 1. Due to topography of the land I had to have so many short legs. However, if I create a line of sight between Pt. 22 and 29 do you think I will give worthwhile angular closure? It is a fairly thick wall of Banyan (Ficus Benjamina) but doable.
> 2. You implied in the note there is another method of centering that might improve the angular misclosure. I used prism poles instead of tripods for my back sight and foresight--as I was not confident that I'll measure the vertical accurately.
> > 
The best centering method is what is called "forced centering", using three tripods and three tribrachs which are set up and remain in place as a succession of FS target, Instrument, and BS target are mounted on them, the trailing tripod and tripod being advanced once the set is complet at an instrument station.
If the time/effort required to rerun the traverse from 21 to 30 (begin on 21 with BS on 20 and end on 30 with FS on 31) is about the same as brushing out the line from 22 to 29, I agree with Norman in that just rerunning that segment of the traverse would probably be what I'd do.
As for alternate methods of centering, you were using bipods for the prism poles, rather than tripods, weren't you? If the bubbles are not 7-minute bubbles or so, there is also room for improvement there. I didn't ask, but is the entirety of the traverse surrounded by jungle or are there any "windows" or lines of sight out to some distant point to which an EDM range can nonetheless be measured?
Kent McMillan, questions for you
Aloha, Kent:
I do have three tripods and three tribrachs and can definitely try the forced centering method. When I experimented this few times, I still have to adjust the tribrach that the TS was sitting when I swap it out with prism. I don't know for sure...but maybe because of the auto compensation feature?
Great, thank you for agreeing with Norman's suggestion.
Guilty as charged! I was using prism poles with bipods. These are small bubbles came with Trimble prism pole...8' i think but don't know for sure.
Surrounding is pretty heavily vegetated or blocked by structures. Even the pastures are surrounded by trees. I think I can take a shot from #16 to #19. We don't even have visible transmission towers 🙁
Let say I drive out somewhere to open space how do I determine EDM range? I never done this before. There is an old runaway that was used for sugarcane crop duster just several miles away. Sugarcane business are long gone so it is a possibility.
Thank you so much Kent!
>
> The best centering method is what is called "forced centering", using three tripods and three tribrachs which are set up and remain in place as a succession of FS target, Instrument, and BS target are mounted on them, the trailing tripod and tripod being advanced once the set is complet at an instrument station.
>
> If the time/effort required to rerun the traverse from 21 to 30 (begin on 21 with BS on 20 and end on 30 with FS on 31) is about the same as brushing out the line from 22 to 29, I agree with Norman in that just rerunning that segment of the traverse would probably be what I'd do.
>
> As for alternate methods of centering, you were using bipods for the prism poles, rather than tripods, weren't you? If the bubbles are not 7-minute bubbles or so, there is also room for improvement there. I didn't ask, but is the entirety of the traverse surrounded by jungle or are there any "windows" or lines of sight out to some distant point to which an EDM range can nonetheless be measured?
Kent McMillan, questions for you
> Let say I drive out somewhere to open space how do I determine EDM range? I never done this before. There is an old runaway that was used for sugarcane crop duster just several miles away. Sugarcane business are long gone so it is a possibility.
The idea is to find a point that you can connect very well to your survey network by some means, preferably angle and distance. Once you have that done, you can leave a target on it and just measure horizontal angles to it from other stations on the network (although angle and distance would be better. Probably the practical limit is how clear the atmosphere is. I don't know the details of the target recognition in your Trimble instrument, but assume that you have the option of manually pointing at the target and measuring the range to it.
This will accomplish the most as the stations to which angles are measured to the remote coordinated point are spaced more widely on the network. They have the effect of controling the azimuths of lines radiating from the network station where the tie is made because the azimuth of the line from the station to the remote point should be significantly less uncertain than the network lines from the station were before the angles to the remote point from them were added to the adjustment.
Kent McMillan, questions for you
Aloha, Kent:
I see what you are saying. Let me do some recon. see if there is possibility. Yes, I can take shots manually.
Thank you very much for taking the time to explain this to me!!
> > Let say I drive out somewhere to open space how do I determine EDM range? I never done this before. There is an old runaway that was used for sugarcane crop duster just several miles away. Sugarcane business are long gone so it is a possibility.
>
> The idea is to find a point that you can connect very well to your survey network by some means, preferably angle and distance. Once you have that done, you can leave a target on it and just measure horizontal angles to it from other stations on the network (although angle and distance would be better. Probably the practical limit is how clear the atmosphere is. I don't know the details of the target recognition in your Trimble instrument, but assume that you have the option of manually pointing at the target and measuring the range to it.
>
> This will accomplish the most as the stations to which angles are measured to the remote coordinated point are spaced more widely on the network. They have the effect of controling the azimuths of lines radiating from the network station where the tie is made because the azimuth of the line from the station to the remote point should be significantly less uncertain than the network lines from the station were before the angles to the remote point from them were added to the adjustment.
