Mapping & Survey
Photo Interval / Motion Blur Calculator
Shutter interval for your overlap target, plus motion-blur risk at your shutter speed.
Planning aid only — not certified flight-planning software or airspace clearance. Always verify results against your own aircraft's manual and check current regulations before flying. Full disclaimer.
Fill in every camera field, altitude, speed and shutter speed to calculate.
The 1-pixel blur threshold is a common photogrammetry rule of thumb, not a hard requirement — some applications tolerate more, some (precision mapping) want less.
What the calculator works out
Give it your camera, height, speed, front overlap and shutter speed, and it returns:
- GSD, the ground size of one pixel at that height;
- Capture spacing, the ground distance between photos needed for your front overlap;
- Capture interval, the time between photos at your speed;
- Motion blur, how far the drone moves during one exposure, in centimetres and in pixels. The result is flagged when blur exceeds one pixel.
A worked example
A DJI Mavic 3 Pro at 80 m has a GSD of about 2.2 cm/px, and each photo covers about 86 m along the flight line. With 80% front overlap:
- photos are needed every 17.3 m;
- at 8 m/s, that is one photo every 2.2 s;
- at 1/1000 s, the drone moves 0.8 cm during the exposure: about 0.4 px of blur, which is sharp;
- at 1/250 s, it moves 3.2 cm: about 1.5 px of blur, which is visibly soft at full resolution.
The blur limit, turned around
The same numbers tell you the fastest you can fly for a given shutter speed and GSD:
Maximum speed (m/s) = GSD (m) ÷ shutter time (s)
At 2.2 cm/px and 1/500 s, that is 0.022 ÷ 0.002 = 11 m/s for one pixel of blur. Halve the height, or the shutter time doubles in dull light, and the safe speed halves too. On an overcast day, when the camera needs a slower shutter, slowing down is often the easiest fix.
Check the camera can keep up
The capture interval must be longer than the time your camera needs to take and save each photo. That time depends on the camera, the file format (RAW + JPEG is slowest) and the memory card. If the interval is too short, the camera skips shots and leaves gaps. Most mapping apps warn you or slow the drone automatically; if yours doesn't:
- fly slower;
- fly higher, if the GSD allows it, because each photo then covers more ground;
- reduce front overlap slightly;
- shoot JPEG only, and use a fast card.
Rolling and mechanical shutters
Many smaller drones, including the DJI Mini and Air series, have an electronic rolling shutter: the sensor is read line by line, so the drone moves while one image is recorded. At mapping speeds this skews the image slightly. Photogrammetry software can correct it if you tell it the camera has a rolling shutter, but the effect grows with speed. Enterprise mapping drones often have a mechanical shutter, which exposes the whole image at once. With a rolling-shutter camera, flying more slowly than the blur limit alone would allow gives cleaner results.
Wind and the interval
The calculator assumes a steady ground speed. Flying into a headwind lowers your ground speed, so a time-based trigger fires photos closer together than planned; with a tailwind they spread further apart, and front overlap drops. Distance-based triggering avoids this. If you have to trigger by time, plan the interval for the tailwind legs, when the drone covers ground fastest. Check the wind at your mapping height with Wind at Altitude before you fly.