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Postby cujo » Sun Dec 21, 2008 2:10 am

Hey, I got a BS issue. :shock:

Had 2 crews out today on a Sat (what bad economy?) and started playing with one of the raw files.

I have known control (might have to post that later) and the first thing they did was setup and do a Set Collection (3 sets) to a new control point. 204

Then they confirmed the orientation and started collecting topo.

Later they turned on the switch to take direct&reverse on topo shots and collected 4 CL ties. 305-308
Note that the switch to collect direct&reverse on the BS was already set on (they never actually ran a BS "set" since that happened in the first Set Collection).

Foremost SurvNet says:
Warning: Could not find appropriate backsight:
IP: 203, BS: 201, FS: 305

Warning: Could not find appropriate backsight:
IP: 203, BS: 201, FS: 306

Warning: Could not find appropriate backsight:
IP: 203, BS: 201, FS: 307

Warning: Could not find appropriate backsight:
IP: 203, BS: 201, FS: 308

Then, looking into the Unadjusted Observations for Hz angles I see:
201 203 305 067-46'45.5" 30.8

However looking at the raw file you'll see:

Note that after the set, when beginning the topo the user was asked to confirm the BS orientation and SurvCE looked into the last Set and pulled out this piece of information:

So, from what I can figure, SurvNet has accepted this BK record, applied it, then halved the angle because it was missing the corresponding BR for the FR? NULLIF

So ... here are some issues to consider:

#1 When the initial Set was taken, the BS had to be established with a reading. Normally this reading (if the direct&reverse is checked on) would require BD and BR to be taken at once, but within the set it decides to start working the set after only the BD ... is this a problem? Should the raw file get a BD and BR up front before the set to actually Set the BS information? Does the BS orientation within Set need to be updated to accommodate the new procedures that have been implemented in 2.x?

#2 When the later FD and FR shots are taken, what BD and BR records are they supposed to use? I'd think perhaps at worst just the last BD and BR in the last set. At best they should use the last BD and BR records taken to actually Set the BS establishment (in this case it did not happen). Had it happened before the Sets, would it have been able bridge the data across the Set observations?

I haven't actually gotten to see the FD/FR outside of a Set be used with a BD/BR. I also haven't tested the idea that if you have direct&reverse turned off to the BS that any direct&reverse FS is supposed to get reduced using only the vertical circle into a FD. That would have solved the problem in this case, but since it was checked "on", it didn't happen. With respect to the BD and BR from the last set not being used, I can't understand why. But it feels like I need to do a thousand iterations of every possible permutation to figure out what will happen when. Next step will be to do a BD/BR orientation, and take some FD and FD/FR readings to see what happens. Then BD orientation and take some FD and FD/FR readings; lastly throwing the Set Collection routine into the mix for I don't know how many additional alternatives.

Out of this experience I'm not sure if all the pieces in the SurvCE puzzle will work together.
Take care,


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