Curve Table

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Curve Table

Postby Vincent Popish » Fri Jul 30, 2004 2:14 pm

It appears that the curve table delta angle rounds down in the seconds, always, even when it should round up. We have an over zealous county review person that is very concerned about seconds. So we have to check all of our curve table info to see if it rounded correctly...
It would be nice if that was fixed in sp9 also. Let me know if you want samples.
Vince Popish
Vincent Popish
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Postby Vincent Popish » Fri Aug 06, 2004 6:35 am

SP9 doesn't fix the rounding problem with the curve table, is this problem considered to small to bother with? It appears to be a simple rounding problem, the delta angle always rounds down, even when it is more than .5 seconds. Please comment on your view (MicroSurvey's) of this problem. We do a lot of Plats and it means about half of the delta angles(statistics) are wrong by a second so that makes the curves not tangent, I agree it is entirely insignificant, but the county surveyor says that the curves need to be tangent or labeled non tangent, so it makes it a pain. Just interested in if you agree this should be fixed or should be ignored.
Vince Popish
Vincent Popish
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Postby rwhatman » Fri Aug 06, 2004 12:51 pm

Hi Vincent

I checked out curve tables and did see that Second only round down
if you set bearings to 1 second. 2 seconds and it round up
10 second seemed to work fine. I compare it with Microsurvey2002
and got the same anwers. Mayby this was long over do.

Here in Ontario we don't show the Delta at all.

Only the Arc, chord, Radius and bearing are required.

We have round all are bearing to 10 second in are drawings to avoid the very thing you are running into.

I know this is not much help.

Maybe when the guys at MicroSurvey get back from there holiday
they wil have answer for you.
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Postby ianw2 » Fri Aug 06, 2004 4:14 pm

Ah!, Mr. Whatman, but then again, you live in the land of enlightenment concerning boundary survey practicality! Your comments fall on deaf ears to those of us who must deal with non-licensed, inexperienced people passing judgment on our professional work product.

Vince, I hear ya, man! We deal with the same stuff here! No equipment available to produce the map specs required by the checkers, but they still demand none the less.

Yes, rounding is a VERY big issue for us in the land of darkness below the 49th parallel. For example, our local standards are that boundaries shall close to within 0.02 feet. No, that’s the entire standard for linear closure. No, I did NOT forget the ratio. It doesn’t matter whether you’re surveying the boundary of an entire section or a 0.1 acre parcel. Yes, I realize that that means the error of closure on the section is 1:105,000 and the error of closure on the 0.1 acre parcel is as low as 1:13,200. Stop laughing, Mr. Whatman! It’s true, I tell you!

Yes, they’re worried about 1 second on angle, too. No, not relative, absolute. That’s right ±1” whether the line is 1 miles long or 50 feet long. Yes, I know that 1” in 5280 feet is approximately 0.03’ while 1” in 50 feet is about 0.0003 feet. Okay, if you insist on laughing, I’m not going to talk to you any more!

The point is, with that kind of “scrutiny”, we have to hand-check every result when we see rounding error problems like this. That really slows things down and creates unnecessary work. We should be able to rely on our CAD software to do this for us.

I won’t even begin to describe the wonderful discussions we’re having regarding Basis of Bearings on maps now that we live in an era with those funny electronic boxes floating in space.
Ian Wilson
Ian Wilson Land Surveying, Inc.
Temecula CA 92591
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Postby rwhatman » Fri Aug 06, 2004 5:02 pm

I would never laugh Ian. I am not a Surveyor, just someone that
has work at surveying for 32 yrs. If you look at the specs of the equipment you use. There is error built in or at least in are equiment.

I have seen drawing to the second before. We even did all are curve
data to the second 10 years ago.

No two crews will ever measure the same. As we show greater accuracy
we lie more and more. Some call it adjust.

I have seen what other surveyors digital drawings. You pick on the curve
data, and it sure it does not match what is typed on the plan, yet cloeses

When you upload your control it is to only 3 places of decemal.
I have improved this by having the cordinates in the 10000,10000 range
that extra 0 make bearings much more accurate.

I was not trying to belittle the problem.

As it turns out I was stepping on little quick sand on this subject.
Wish the best of luck

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Postby Darcy Detlor » Tue Aug 10, 2004 8:19 pm

This is a puzzle because most routines like this funnel through a small group of functions. Something must be slightly different for the delta calculation.

We will fix this one. Every second is important.
Darcy Detlor,
MicroSurvey Software Inc.
[email protected]
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