I´m working on a project to map a colleague´s farm, and then ultimately digitizing that information to produce maps and signage.

To start, we´re focusing on a small agroforestry plantation. We want to capture the fenceline (borders which essentially form polygons), irrigation lines and the locations of a different types & species of trees.

Aerial imagery isn´t that great for this area and we need to be more precise than our GPS unit allows, so we´ve begun doing everything old-school: measuring tape, protractor, pencil & paper.

What´s the best way to make sure all of our lines and angles are accurate & true?

Fencelines around the area form a kind of "hour glass" -shaped polygon, so nothing is really parallel nor perpendicular to anything else. Irrigation lines are more or less straight, with some variance following natural curvature, etc.

After we´ve made all the measurements and have everything locked in & drawn to scale, what sort of program is recommended to digitize (and geo-reference) everything?

I have no experience with AutoCAD, but I feel like it´s inevitable at this point.

closed as too broad by Vince, whyzar, nmtoken, PolyGeo Mar 20 at 21:18

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  • on question 2 you can use QGIS, no need to digitize, just enter the values – nmtoken Mar 20 at 19:55

There's a free, Windows-based software called Copan that allows you to convert all kinds of land survey measurements into coordinates. The calculation types are often known as COGO (for coordinate geometry).

If you can measure angles accurately -- I'm not sure you can from your description -- you would measure and calculate and adjust a traverse: a sequence of angles and distances.

If you can only measure distances accurately, you would COGO many distance-distance intersections, or possibly distance-and-offset calculations.

To geo-reference your work, you would either need to know existing coordinates of, or conduct several repeated GPS measurements at, a corner of your plantation. (You indicated that your GPS is not reliable but the repetition and averaging increases the reliability.)

To orient your survey, you might just use a magnetic compass or do more GPS measurements at another, far from the first, corner of the land.

You can export your coordinates as a textfile for input to a drawing program, or even use Copan Pro (not free).

If you need detailed help on specific aspects of the survey calculations, you'll need to study other questions here on Copan or ask separate but more specific questions here. If it's all a bit too daunting, you should seriously consider hiring a trained surveyor.

Note: I am a former developer of Copan.

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