--- title: "Drone GSD and overlap calculator for mapping and photogrammetry" description: "Work out the ground sampling distance (cm per pixel), the photo footprint, the spacing between photos and flight lines and the shutter interval for a mapping flight." canonical: https://droneweatherforecast.app/tools/gsd-calculator lang: en site: Drone Weather Forecast updated: 2026-11-14 alternates: - lang: pt-BR url: https://droneweatherforecast.app/pt/tools/gsd-calculator - lang: es url: https://droneweatherforecast.app/es/tools/gsd-calculator html: https://droneweatherforecast.app/tools/gsd-calculator markdown: https://droneweatherforecast.app/tools/gsd-calculator.md llms_txt: https://droneweatherforecast.app/llms.txt --- # GSD and overlap calculator for drone mapping > Work out the ground sampling distance (cm per pixel), the photo footprint, the spacing between photos and flight lines and the shutter interval for a mapping flight. *Last updated: 2026-11-14* ## What the GSD is The **ground sampling distance (GSD)** is the size of one pixel on the ground. A GSD of 2 cm/px means each pixel of the photo covers 2 × 2 cm, so nothing smaller than a few centimetres can be measured in the map or the 3D model made from it. It depends on three things: how high you fly, the lens and the number of pixels. ## How the calculator works Spec sheets rarely give the real sensor size and focal length, but every drone lists the **35 mm-equivalent focal length** and the photo size in pixels. The equivalent focal length is defined against the 43.27 mm diagonal of a full-frame sensor, so: - photo diagonal on the ground = height × 43.27 ÷ equivalent focal length; - the aspect ratio splits that diagonal into the width and the height of the footprint; - GSD = footprint width ÷ photo width in pixels. For the mapping grid, the long side of the photo lies across the flight line, as in most mapping apps: - distance between photos = footprint length along the line × (1 − front overlap); - distance between flight lines = footprint width × (1 − side overlap); - time between photos = distance between photos ÷ speed. ## Worked example A Mini-class camera with a 24 mm equivalent lens, 12 MP photos in 4:3 (4,032 pixels wide), at 100 m: - ground diagonal: 100 × 43.27 ÷ 24 ≈ 180 m, so the footprint is about **144 × 108 m**; - GSD: 144 m ÷ 4,032 px ≈ **3.6 cm/px** (about 1.8 cm/px in 48 MP mode, 8,064 pixels wide); - with 75 % front and 70 % side overlap: a photo every **27 m** and flight lines **43 m** apart; - at 5 m/s: one photo every **5.4 s**. The GSD is proportional to the height: at 50 m the same camera gives about 1.8 cm/px in 12 MP mode, but each photo covers a quarter of the area, so the flight takes roughly four times as many photos. ## How much overlap Pix4D, a photogrammetry software maker, recommends at least **75 % front and 60 % side overlap** for a general mapping grid, at least 80 % on both for flat fields, and 85 % on both over forests and dense vegetation, where matching points between photos is hard. More overlap means more photos and a longer flight, so plan the battery and the wind: a mapping flight crosses the area many times, upwind on every other line. ## Wind and light - **Wind:** flying into the wind on every other line changes the speed over the ground, and with it the spacing of photos taken at a fixed interval. Use distance-based triggering if your app has it, and check the [wind against your drone's limit](https://droneweatherforecast.app/tools/drone-wind-calculator) at the height you will fly. - **Motion blur:** at a given shutter speed, the drone moves farther during the exposure when it flies faster; keep the movement during one exposure well under one GSD. - **Light:** even, overcast light gives the most uniform maps; low sun leaves long shadows that change between flight lines (see the [golden hour calculator](https://droneweatherforecast.app/tools/golden-hour-calculator) to avoid it). ## Sources - DJI Mini 4 Pro specifications (24 mm format equivalent, 8064×6048 maximum image size): [dji.com](https://www.dji.com/mini-4-pro/specs) - Pix4D, recommended image overlap for nadir mapping: [support.pix4d.com](https://support.pix4d.com/hc/en-us/articles/202557459) ## Frequently asked questions ### What is a good GSD for drone mapping? It depends on what you need to see. A few centimetres per pixel is common for site surveys and volumes; finer detail, such as cracks, needs a GSD below 1 cm/px, which means flying lower or using a longer lens. ### How do I get a smaller GSD? Fly lower, use a longer equivalent focal length or shoot more pixels (48 MP instead of 12 MP). Halving the height halves the GSD. ### How much overlap do I need for photogrammetry? For a general mapping grid at least 75 % front and 60 % side overlap, as Pix4D recommends; 80 % or more over flat fields and 85 % over forests. ## More tools and guides - [Drone wind calculator](https://droneweatherforecast.app/tools/drone-wind-calculator) - [Wind at altitude calculator](https://droneweatherforecast.app/tools/wind-at-altitude-calculator) - [Wind speed converter and Beaufort scale](https://droneweatherforecast.app/tools/wind-speed-converter) - [Return-to-home calculator with headwind](https://droneweatherforecast.app/tools/return-to-home-calculator) - [Golden hour and blue hour calculator](https://droneweatherforecast.app/tools/golden-hour-calculator) - [Drone pre-flight checklist](https://droneweatherforecast.app/guides/drone-pre-flight-checklist) - [How much wind can a drone handle?](https://droneweatherforecast.app/guides/how-much-wind-can-a-drone-handle) ## Get these checks for your flight, hour by hour Drone Weather Forecast runs them for you: the hourly wind and gusts against your drone's limit, wind by altitude in Pro, KP index and GPS satellites. Free on Android and iOS, no ads. - [Get it on Google Play](https://play.google.com/store/apps/details?id=xyz.droneweather.app) - [Download on the App Store](https://apps.apple.com/app/drone-weather-forecast/id6768126094)