Entering bearings in COGO command

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Entering bearings in COGO command

Post by cbunker » Thu Jan 10, 2008 8:16 am

We just ran across an issue here in our office where we found out that MSCAD 2005 will accept bearings that "don't make sense", essentially. One of our technicians entered a bearing with 65', rather than 5', and MSCAD accepted the value, rounded the degrees up by one, and changed the minutes to 5' - I guess this is a good thing, but it's just something to be aware of in your QA procedure - MSCAD won't generate an error message to indicate this kind of typo to the user, so it has to be caught in the review process.

I did a little further testing, with an extreme case as follows:

1 S87°53'55"E dist= 27.183 N= 0.000 E= 0.000 2 T
Bearing input=191.6565 Distance Input=10
--> notice the bearing rounded OK, but the distance was completely off

1 S42°22'07"W dist= 27.183 N= 0.000 E= 0.000 2 T I
--> the resulting inverse, bearing is completely different here from the original calc

1 N46°01'10"E dist= 10.000 N= 27.028 E= 25.515 3 T
Bearing input=145.6070 Distance Input=10
--> a simpler test, result is as expected.

I'm not looking for a solution here, this is more of a head's up to everyone, just to be aware that the person doing the data entry can easily make a mistake and not be aware of it. And if you're not doing a diligent, line-by-line comparison to the source of the data, the reviewer may miss it as well.

Chris Bunker, BMath, O.L.S., C.L.S.
T. A. Bunker Surveying Ltd.
150 John St. N., P.O. Box 1180
Gravenhurst, ON P1P 1V4

Glen Cameron
Posts: 1395
Joined: Fri Nov 08, 2002 12:18 pm
Location: Corbeil, Ontario, Canada

Post by Glen Cameron » Thu Jan 10, 2008 9:36 am

No matter how we handle this, human entry errors are always something that will cause problems if they are not caught. Whether we round off bearings or not will not catch human entry errors. Humans checking humans can catch some errors but also miss others - that is the nature of humans. The rounding and conversion of what may seem to be faulty bearings, is a tool that can be used by people that have problems adding two bearings correctly, and can enter in the number directly so we do the conversion for them.

I went to a clean new drawing and entered in a single point at 0,0,0 and then used the bearing and distanc eiput you used, here are my results in MicroSurvey CAD 2008 SP#1.

Enter Quadrant Bearing like QDD.MMSS:<Backup>Bearing used = S87°53'55"E
Options: C#=-*/sin/cos/tan... or Pt..Pt(+-*/) a Distance
Enter the Distance: <Backup>Distance used = 10.000000
Pick or Enter the Solve Point: <2>(Backup Toggles):
Enter Description:<>:
1 S87°53'55"E dist= 10.000 N= -0.367 E= 9.993 2
Bearing input=191.6565 Distance Input=10

I am not sure why yours would show something different than you entered for the horizontal distance.
Glen W. Cameron, C.E.T.
City of North Bay, Ontario

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