updated: 24-Mar-2011

 Copan for Windows

Area and Perimeter Calculations

If you have a set of points in a coordinate file, any suitable sequence of such points can define a structural alignment or property boundary. An alignment or boundary is a sequence of straight line segments and circular curve segments, joined end to end.

Use this module to calculate the geometry of any number of such sequences, including ones with curves. The resulting geometry includes azimuths (or bearings) and horizontal distances of straight segments, parameters of curved segments, perimeters (or overall lengths) of lines, and areas of fully enclosed shapes (or loops).

We call it inverse map traversing or inverse bearing and distance traversing because, like inverse calculations in the § COGO module, it determines bearings and distances between given points, and because the interface and reporting are virtually identical to those of the § Map Traverse and § Map Check modules (which you should use if you need to actually apply or check bearing and distance traverse data).

1. To Inverse Traverse Coordfile Points

1. Calculate | Inverse Brng-Dist Traverse (Area Calc)...
2. Optionally Load... a traverse Data file. (see Map Traverse Files below).
3. Optionally enter conversions: an Azimuth Correction, to be added to computed bearings; a Units Factor, for converting computed distances to other units; a Scale Factor, for combined map projection and sea-level conversion from computed distances to other coordinate system distances.
4. Enter or edit the point traverse data in the big edit box. See below for a description of map traverse data for calculating areas and perimeters.
   To move the text cursor within the big edit box, use the Arrow, Tab, or Enter keys, or the mouse pointer. Do not use the Space key to separate fields. To delete a chunk of text, select it with the mouse then click Cut (or type Ctrl-X) but be careful not to delete the embedded tabs within a line. To manually insert a tab, Copy and Paste an existing one. The Ctrl-Insert and Ctrl-Delete key combinations act like the Ins and Del buttons, that is, they insert and delete a line of data. To add a Point number automatically to the next blank line, press Enter when in the Distance column of the previous line.
5. Optionally List the map traverse Data.
6. Save the Data for reuse.
7. Optionally Export.. in ESRI format or Reverse the direction of the map traverse Data.
8. Calculate (or OK) the traverses.
9. To graphically view the traverses: Close or hide the Info Display window if it is open, and minimize or move aside — but do not close — the Area Calc window.

click for larger view

2. Map Traverse Data for Calculating Areas and Perimeters

• Begin each traverse by a starter line, which must not only contain the first point number, under Point, but also contain a traverse label, under Trav Label, identifying the traverse.
• A traverse must have a sequence of leg lines. Each leg must contain a Point number and may contain a Curve Code (see § Traversing Curves on how to define curves along a map traverse). Nothing else is allowed.
• All identified points must already exist in the coordfile.
• Blank lines may be used for readability but have no affect on or calculation.

3. Map Traverse Files

• The first line must contain only this text:
      Map Traverses
• The next three lines can contain anything as they are not currently used.
• The next three lines must contain the head correction values — scale-factor, units-factor, and azimuth-correction — one each per line, respectively.
• Each subsequent line must be a tab-delimited data line with six fields:

      point-num, blank, blank, trav-label, blank, and curve-code

  Most of those fields are empty but there must be five tabs per line. Which fields are left blank depends on the purpose of the particular data line (see Map Traverse Data for Calculating Areas and Perimeters above).

• Single-byte character encoding, such as ANSI, DOS or UTF-8 must be used. Note: multi-byte character encodings (such as Unicode or UTF-16) will not work.

Example Map traverse file.

Map Traverses
1st dummy line
2nd dummy line
3rd dummy line
1.0000000000
1.0000000000
0.0000000000
101     parcel D
102
103             tbc
104             c
105             tec
106
101

4. Export

Use the Export... button to export the current map traverses (starting from where you specify), in ESRI Traverse File format.

You specify the location and file name (the default being the current folder and current map traverse file, without the .mt) and Copan will save to file-name\file-name.txt (that's the funny way ArcGIS expects it).

Copan uses the latest coordinates for the start and end of each traverse, and outputs traverse data in their converted form (i.e., after conversions are applied).

5. Reverse

Occasionally, you'd like to use an already entered traverse but in the reverse direction. Use the Reverse button to reverse the current map traverses (from last to first), each one in reverse point order.

6. Notes

• If you have multiple traverses, when you Calculate you may begin from a specific traverse rather than from the top by entering the start point number or traverse label.
• If a traverse is a loop (i.e., it ends on its own start point) Copan provides the enclosed area in squared distance units. And if a units factor was involved, the area is also given in converted units. For example, if distances are entered in feet and a UF=0.3048 conversion is entered, then area is given in m² and in ft².
• Copan does not calculate areas that are only enclosed by separate different traverses, but it does still calculate all the other paramaters of any non-loop traverses.
• If Copan complains about the data when calculating, and you cannot see what is wrong, visually inspect the data by selecting it all with the mouse. Often, you can see the inconsistency via the selection block outline.
• List All... is equivalent to the sequence List data and Calculate.

updated: 24-Mar-2011