Field guide
From known endpoints to a checked setting-out file
A useful subdivision starts with a clear interval rule, an agreed coordinate frame and a deliberate endpoint policy.
Choose equal segments or a fixed interval
A line division calculator turns two known planar positions into a sequence of design coordinates. Start with the physical task: do you need a specified number of equal bays, or a repeated spacing that may leave a shorter bay at the end? These are different instructions. Select number of segments when every bay must be identical. Select fixed spacing when the distance between successive interior points is prescribed. The calculator works along the horizontal straight line from A toward B; it does not follow a curved alignment, terrain surface or sequence of intermediate survey observations.
For four equal segments, the interior fractions are one quarter, one half and three quarters of the full line. Including both endpoints gives five output records. Excluding both gives three. Enter the number of segments, not the number of desired points. Changing endpoint flags only changes which endpoint records appear; it does not redistribute the interior coordinates. This distinction is useful when existing control points already represent the ends of a setting-out line.
Understand the short final interval
For a horizontal length of 10 units and a fixed interval of 3, the stations from A are 0, 3, 6 and 9. If B is included, the final station is 10 and the last interval is 1. The report shows three full intervals and a residual of 1. If B is excluded, that residual still describes the distance from the last regular station to the physical endpoint. It does not imply that an extra point was generated.
When the spacing divides the line exactly, B is emitted only once if selected. When the spacing exceeds the line length, there are no interior stations; the selected endpoints can still be output. If no endpoints are selected in that situation, the tool reports an empty result instead of supplying an apparently successful empty file. Reversing A and B reverses the spacing origin and may move the short interval to the other end, so confirm the direction before assigning field point numbers.
Read existing coordinates without guessing their meaning
You can enter A and B manually or read an existing CSV or TXT point table. In file mode, confirm the delimiter, header, coordinate columns and unit labels before reading. Then choose A and B by their physical source record start lines. The displayed point names and coordinates help distinguish identical names or files whose order differs from the expected point numbering. A source line number is a location in the imported file, not a point identifier. XLSX workbooks are also accepted for this input: explicitly choose the worksheet, and replace formulas, dates or error cells with plain values before importing.
Easting is E and northing is N throughout this interface. Some regional exports label northing as X and easting as Y, while other software uses X for easting. Map the numerical columns from the source specification rather than relying on the letters alone. Unit selectors describe the supplied values; they do not convert feet to metres. Both endpoints must belong to the same planar frame and horizontal unit. Latitude and longitude in degrees require an appropriate projection before this workflow.
Calculate positions and decide how to treat height
For a fraction t along the line, the horizontal coordinates are E = EA + t × (EB − EA) and N = NA + t × (NB − NA). Equal subdivision uses t = i / n for interior index i and segment count n. Fixed spacing uses t = distance from A / total horizontal length. The preview reports that distance so a reviewer can compare the generated sequence with the specified setting-out interval.
Elevation interpolation is a separate, optional decision. When enabled, both endpoint heights must be known and valid; the same fraction gives Z = ZA + t × (ZB − ZA). This is a straight grade between endpoints, not a terrain profile, measured intermediate height or vertical curve. When interpolation is off, all generated elevations remain blank, including generated endpoint copies. Original elevations in an appended source table are preserved. A known horizontal position does not establish a reliable elevation by itself.
Assign point numbers before making a field file
Choose a text prefix, starting nonnegative integer and minimum digit width. For example, prefix DIV-, start 1 and width 3 produce DIV-001, DIV-002 and DIV-003 in order from A to B. Padding adds leading zeroes to short numbers; it does not truncate longer ones. A generated point name that already exists anywhere in the loaded source blocks the result, even when you plan to export only new points. Pick a numbering range reserved for this design operation.
Coordinate coincidence is different from a point-name collision. Including A or B often generates a new record at an existing endpoint position. The summary counts exact coincidences with loaded positions. If you append the output, both source and generated records remain under different names. Nothing is merged automatically. Exclude the relevant endpoint or review the combined file with the duplicate point tool when a downstream collector expects only one record per physical position.
Preview, apply and export a traceable result
Read the length, selected method, nominal spacing, full interval count and residual before inspecting individual rows. The north-up diagram makes direction and ordering easier to review, while the table retains the actual coordinates. Selecting a row or plotted point displays its identifier, position, fraction and distance from A. The overview is bounded to keep large jobs responsive; selecting another record brings it into the preview, and exports still contain every generated point.
Apply reviewed points enables the point CSV download. The file uses Point, Northing, Easting, Elevation and Description columns, with LINE_DIVISION identifying generated records. When appending, original source values and additional unmapped columns are retained; extra fields for new points are blank. The distance audit CSV records the generated stations for independent checking. The JSON report includes the source interpretation, endpoint provenance, parameters, generation time and whether the preview was applied. Changing an input invalidates the previous result so an old download cannot silently represent new settings.
Respect precision and practical limits
Each output is limited to 100,000 points, including original records when appending, and the point CSV is limited to 10 MiB. A very small spacing on a long line can exceed that limit before a preview is produced. Increase spacing or divide the job into documented portions rather than assuming that only the visible rows will be exported. Calculations run locally in a worker, and cancellation retains your inputs for adjustment.
Decimal coordinate strings are retained for endpoint values, and equal fractions use decimal arithmetic to avoid losing small offsets solely because a local origin is large. Fixed-spacing positions depend on the computed horizontal length and therefore have finite numerical precision. Distances on screen are rounded to six decimals, with scientific notation for very small nonzero values; exports retain the calculation values. Extra digits are not evidence of field accuracy. Check a known station independently and retain the original coordinates alongside the generated design file.
Use the result in a controlled survey workflow
Typical uses include equally spaced fence posts along one straight run, reference marks on a construction baseline and intermediate design points between approved endpoints. The calculation does not resolve right-of-way boundaries, select project control, apply grid-to-ground factors or account for offsets from the line. Those decisions must be established before the points are generated. A zero-length horizontal line is rejected even if endpoint elevations differ, because no horizontal subdivision direction exists.
After export, reopen the point file in the destination software and verify column order, units, leading zeroes and the first and last positions. Compare at least one interior coordinate and its distance from A with an independent calculation. If you need perpendicular offsets, a point-to-line check can review those separately. If the task follows several alignment segments, process each with its own documented origin and endpoint policy instead of treating this straight-line tool as a route-stationing system.