Bug in Trimble Access (rare)
I saw a bug in Trimble access this week that I have seen before, but since it is not possible to directly contact Trimble, I am posting it here hoping that it will be brought to their attention. When I saw it previously, I send a message to my dealer about it, but obviously it didn??t go anywhere. I have been using Trimble now for 36 years, and my biggest complaint about them is the lack of a direct method for reporting bugs and other issues.
A lot of our monitoring projects have sets of colinear points. I was on one this week that has a monument at each end and 18 alignment pins in between, nominally on the line. The distance between the monuments is 607 meters. I set up on the two endpoints and also on a point about halfway and observe each alignment pin using a total station, as well as three reference monuments off of the line. When I setup on the middle point, I backsight one monument at the end of the line and turn rounds to the monument at the other end. I always use grads, where 200g=180?ø. When doing these rounds, some readings to the far monument are slightly under 200g and others are slightly over. After each round, Access shows a results page with differences, which are usually around 0.1 to 0.3 milligrads. After the second or third round, I noticed the angle to the far monument came up on the summary as being many degrees off. I was doing 4 rounds, so I added another round, total 5. Here are the values observed (grads):
Standpoint
Backsight
Forepoint
HI
HT
Angle Right
A05
M1
M2
1.758
1.841
200.001494
A05
M1
M2
1.758
1.841
199.999845
A05
M1
M2
1.758
1.841
199.999726
A05
M1
M2
1.758
1.841
199.998699
A05
M1
M2
1.758
1.841
200.000516
A05
M1
M2
1.758
1.841
199.999590
A05
M1
M2
1.758
1.841
200.002180
A05
M1
M2
1.758
1.841
200.000502
A05
M1
M2
1.758
1.841
199.999331
A05
M1
M2
1.758
1.841
200.001686
The mean is 200.000357g (180?ø00 ¨«01.16??), ? is 0.001129g (3.66??). The data is a bit noisy because the lines of sight are parallel to the ground (concrete one direction and asphalt the other direction) about 1.5 m above ground, so lots of heat waves. This was done with autolock on a 1? high accuracy S6.
The values for the mean angle stored in the access file are 280.000357028, which is exactly 80g off (1/5 of a circle, maybe because there were 5 rounds?), and a ? of 160.99674g. To get that as an average, I would have to add 800g (two full circles) to the sum of the individual readings.
Looking at the .jxl file, each individual pointing (10 total, 5 D and 5R) shows the correct value, these are listed in the table above.
To summarize, the function in access that is keeping track of the directions observed in rounds got one or more pointings wrong by integer values of a full circle) in the mean turned angle computation, but actually stored the correct values for each individual sighting.
Software which reads the mean turned angle value and associated standard deviation will use the wrong value, while software which reads every individual pointing and then computes a standard deviation will have the correct data.
I know the explanation is somewhat convoluted and maybe hard to understand if you aren??t familiar with trimble access files. Hopefully someone from Trimble will contact me and I can send them the .job file. As I said, this isn??t the first time this has happened, and the other times I have seen it was always when the angles were close to and on either side of 200g (180?ø).
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