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Curve fit

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Bruce Small
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Possibility one: I'm hallucinating, in which case I'm going back to bed with my Kindle.

Or, two: Someone posted six coordinate pairs and asked for help fitting a 430' curve to them. I did that quickly enough, but the post has disappeared. Did anyone else see it?


 
Posted : May 11, 2026 11:50 am
jhframe
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I was contacted privately about the same thing, but when I offered to help he replied that he decided to head into the office to do it himself.


 
Posted : May 11, 2026 11:55 am
Bruce Small
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My solution, assuming I copied the original post coordinates correctly. Point 4 is my calculated average radius point. It appears 251 is an outlier, slightly.

Point Northing Easting

00245 +1,530,906.0579 +511,228.5823
00246 +1,530,784.9861 +511,118.9292
00247 +1,530,701.2922 +510,906.1986
00248 +1,530,698.9316 +510,859.9669
00251 +1,531,041.3189 +511,281.6025
00252 +1,531,304.1124 +511,253.5204

00004 +1,531,128.9400 +510,860.8100

Inverse WENDELL curve fit 05-11-2026 12:44:20

00004-00248 S 00 06 44.4 W 430.0092 +1,530,698.9316 +510,859.9669
00004-00247 S 06 03 30.4 E 430.0497 +1,530,701.2922 +510,906.1986
00004-00246 S 36 53 10.6 E 430.0347 +1,530,784.9861 +511,118.9292
00004-00245 S 58 46 57.9 E 430.0382 +1,530,906.0579 +511,228.5823
00004-00251 S 78 14 14.8 E 429.8183 +1,531,041.3189 +511,281.6025
00004-00252 N 65 57 36.9 E 430.0079 +1,531,304.1124 +511,253.5204


 
Posted : May 11, 2026 1:45 pm
jhframe
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Just for fun, I ran the points through Star*Net, holding the radius fixed and using the instrument settings for my GeoMax Zoom 80.  I came up with a slightly different radius point:

1,1531128.90532,510860.76114,CALCULATED RADIUS POINT

251 shows up as an outlier in my calcs as well.


 
Posted : May 11, 2026 3:10 pm
Norman_Oklahoma
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For the record, I did a best fit arc through the points using Civil3d. That routine doesn't allow for fixing the radius, but it calcs out close. Tight, notwithstanding that one outlier.

The radius point falls between Bruce's and Jim's .....


This post was modified 3 weeks ago by Norman_Oklahoma
 
Posted : May 12, 2026 9:50 am