Zerdly

Photo Overlap Calculator

Front and side overlap — or the gap — from photo spacing, a target overlap, or speed and trigger interval, with camera-cadence checks.

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How to use this calculator

Inputs

Front and side overlap — or the gap — from photo spacing, a target overlap, or speed and trigger interval.

Along track (front)
Timing

From your camera's documentation or your own test — no preset is assumed.

More options
Across track (side, independent)

Enter the values and press Calculate.

Or load an example to see a worked result.

Consecutive footprints along track
Illustrative
Consecutive footprints along trackThree equal footprint rectangles along the flight direction with their centre spacing; overlap is shaded and a gap is marked.pF_aflight direction →
Consecutive footprints along the flight line; the shaded band is ground seen by both photos, and its length is F − p.
Calculate first: a stale result cannot be exported.

Batch from CSV

One row per calculation, with a header row. Values use the units currently selected in the form above. Up to 10,000 rows; nothing is uploaded.

Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.

How to use this calculator

  1. Choose forward (spacing → overlap), inverse (target → spacing) or timing (speed × interval).
  2. Enter the along-track footprint and the matching values; units can be m or ft, m/s or km/h.
  3. Optionally add the camera's minimum interval and an across-track footprint with a line spacing (independent side overlap).
  4. Read the overlap or gap, the photo step and the trigger feasibility.

How it works

Front overlap = 1 − p ÷ F_a; side overlap = 1 − q ÷ F_c — independent, never multiplied together. Timing: p = speed × interval; inverse: p = F_a × (1 − overlap).

A spacing wider than the footprint is a GAP of p − F_a (and 100 × (p ÷ F_a − 1) % of the footprint), never a negative percent. Zero spacing is a degenerate, non-travelling state.

If the required interval p ÷ v is shorter than the camera's minimum, the fastest compatible speed p ÷ t_min is shown and the plan is flagged — nothing is clamped silently.

Worked example

F_a 150 m, photos 30 m apart; and an 80 % target at 10 m/s. 1 − 30 ÷ 150 = 80 % front overlap. At 180 m apart there is a 30 m gap (20 % of the footprint). For 80 % on a 100 m footprint p = 20 m; at 10 m/s that needs a photo every 2 s, so a camera limited to 3 s allows at most 6.666667 m/s.

Frequently asked questions

What overlap should I use?

It depends on the terrain, texture and what you reconstruct; capture geometry alone does not guarantee a good model, and water, sand or dense vegetation can fail at any overlap.

Why not multiply front and side overlap?

They describe different directions. Their product is not a meaningful 'total redundancy'.

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Cite this tool

Zerdly. (2026). Photo Overlap Calculator. Retrieved from https://www.zerdly.com/tools/photo-overlap-calculator/

Tip: Enter any known values to calculate the remaining results.

Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.