Any Surveyors?

[Jacob Wall]

(06-15-2014 02:38 PM)Peter Murphy Wrote:  Hello Jacob,

No surveyor here, but I'm interested in your area calculation: "Calculate the area of a polygon by entering the points along the perimeter. Curved and straight segments can be used."

For straight segments I guess that you use the "surveyor's formula," but it would be interesting to know for sure and in detail. For curved segments I have no guess at all.

Thanks for some words on area for the 50g et al.

Hi Peter,

In very general terms, I calculate the area of a polygon that connects any curved segments from beginning to end of curve, ignoring the curve during the first pass. Next the segment areas of all curve segments are calculated and then added or subtracted from the first polygon area calculation, depending on position of curve relative to the chord. The whole thing is completely automated so that the user only enters the perimeter points. From the help option of the program you're referring to:

-- Straight Segments --
1.Enter point numbers separated by spaces> Eg: 1 2 3 4 5
2.Enter a range of point numbers to be used in sequence> Eg: 1..5

-- Curve Segments --
1.Curve Right, enter BC+CC+EC> Eg: 1+2+3
2.Curve Left, enter BC-CC-EC> Eg: 1-2-3
3.Compound Curves, enter each curve individually> Eg: 1+2+3 3-4-5

Of course point numbers simply are used to refer to a set of x,y coordinates stored in a database. I can post a numerical example to illustrate the math if you're interested.

Jacob