What it does

Land Surveyor builds an ordered field boundary from coordinates entered manually or captured through browser geolocation. After three or more vertices are added, it closes the polygon and estimates horizontal area in square metres, hectares and mu.

Estimate, not a cadastral survey

The app is intended for rapid field screening. It does not replace a projected GIS workflow, a calibrated GNSS receiver or a legally valid boundary survey.

Before you start

• Plan to add boundary vertices sequentially, clockwise or counterclockwise.
• For manual entry, use decimal latitude and longitude in WGS84-style coordinates.
• For device location, use HTTPS and allow geolocation when prompted.
• Capture more vertices around curves, but avoid duplicate points and self-intersecting paths.

Quick workflow

1. Optionally select Check location access to inspect permission availability without adding a point.
2. Enter Latitude (Lat) and Longitude (Lng), then select Add Point; or select Add current location.
3. Continue around the field boundary in order.
4. Review the Live polyline preview and delete any incorrect vertex from the Coordinate list.
5. With at least three points, select Close Polygon.
6. Read the area estimate or select Reset to begin again.

Controls & outputs

Control or panel	Actual behavior
Check location access	Reports whether browser geolocation appears granted, available for prompting or blocked. It does not add a point.
Latitude (Lat) / Longitude (Lng)	Accept decimal values in -90…90 and -180…180.
Add Point	Appends one manual coordinate and reopens a previously closed polygon.
Add current location	Requests a fresh high-accuracy browser position and stores the reported accuracy in the point source label.
Close Polygon	Enables the filled preview and area calculation when at least three points exist.
Delete	Removes one vertex; close the polygon again to update the result.
Reset	Clears points, inputs, calculation and messages.
Area estimate	Shows m², hectares (m² / 10,000) and mu (m² / 666.6667).

How it works

The calculator uses the mean latitude and longitude as a local reference. Longitude differences are scaled by the cosine of the reference latitude, latitude differences are converted with an Earth radius of 6,378,137 m, and the projected vertices are passed to the planar shoelace formula.

The SVG preview normalizes the latitude and longitude extents independently so every captured shape fits the frame. It is a schematic ordering aid, not a georeferenced or scale-preserving map.

Data, privacy & external services

Manual coordinates, device locations and results stay in the current browser tab. There is no server calculation, map provider or automatic upload. Browser geolocation is the only protected capability used.

The current version does not persist a survey or export its coordinates. Copy any coordinates you need before refreshing or leaving the page.

Limitations

Accuracy boundary

• The local planar approximation is most appropriate for relatively small field parcels away from the poles and date line.
• The app does not detect self-intersection, duplicate vertices, holes or multiple polygons.
• Browser-reported GPS accuracy can be much larger than the coordinate display precision.
• The result represents a horizontal planar estimate, not terrain surface area.
• Do not use the result as a legal, cadastral, construction or land-transaction measurement.

Troubleshooting

Problem	What to check
Add current location is unavailable	Use manual entry or enable geolocation support and permission in the browser and operating system.
A coordinate is rejected	Confirm that both values are decimal numbers within the displayed latitude and longitude ranges.
Area is not shown	Add at least three points and select Close Polygon.
The shape looks stretched	The preview fits latitude and longitude independently; use the coordinate list and area result rather than treating it as a map.
The area is implausible	Check point order, duplicate points, accidental outliers and device location accuracy.

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