Processing (orthomosaic, DSM)

Processing is DroneField’s core action: from drone imagery it produces the orthomosaic (a unified, orthorectified RGB image), the DSM (surface model), and — when requested — the multispectral vegetation indices.

Processing runs entirely locally: no cloud, no queue. Your data stays on your machine.

See it in action: 1,782 Phantom 4 Multispectral images processed in 20 seconds on a MacBook M4:

Starting

1. Open a project with imported imagery.
2. In the Actions section of the left sidebar, click Process.
3. The Processing settings panel opens.

The processing settings panel

The main controls:

Target GSD (resolution)

GSD = Ground Sampling Distance, i.e. how many centimetres on the ground a single pixel represents in the final orthomosaic. DroneField’s supported range:

• Minimum: 2 cm/px — or the GSD of your source images, if that is coarser
• Maximum: 20 cm/px

You set the value with a slider; any value inside the range is acceptable. The labels under the slider — Flight planning, Precision farming, Quick overview — are only guides to the typical use of each part of the scale, not buttons.

The lower limit follows your images: DroneField reads the native GSD of the photos (flight height ÷ camera focal length) and shows it under the slider — Source images: 4.8 cm/px. The slider cannot go below it, because a finer target would only upscale the photos without adding detail. If you flew a survey at 5 cm/px, the minimum is 5; if you flew low at 1 cm/px, the 2 cm/px limit applies.

Recommended values by purpose:

• Drone-applied application map: 5–7 cm/px
• Ground (tractor) application: 10 cm/px
• NDVI analysis: 3–5 cm/px
• Plant counting: 2 cm/px (fly low, so the source images are 2 cm/px or finer)

The smaller the GSD (e.g. 2 cm/px), the:

• More detail in the orthomosaic
• Larger the file size
• Slower the processing (2–4× longer)

New projects are created with a target GSD of 5 cm/px (set in the new-project dialog); the slider here starts from the project’s value and can be changed before each run.

Multispectral processing

Only meaningful for P4M or M3M. The switch turns on automatically when the project contains multispectral bands. When enabled:

• The individual MS bands (G, R, RE, NIR) are orthorectified as separate band files in Layers/
• All multispectral vegetation indices (NDVI, GNDVI, NDRE, EVI, VARI) become available on the MS index layer
• Processing time increases roughly 40% (multi-band rendering)

For RGB-only drones this switch is disabled — RGB indices (VDVI, NGRDI, ExG, VARI) are generated later from the orthomosaic on first use (see Vegetation indices).

Terrain mode

Turn this on for hilly terrain. Then:

• Twice as many tie points between images
• A finer-grained surface-model grid for more accurate terrain
• A more detailed 3D terrain surface (see 3D Map)
• Processing is ~50% slower

On flat terrain (e.g. Hungarian Great Plain), leave it off — it needlessly slows things down.

High resolution (HQ)

The High resolution (native) switch, below Terrain mode. When enabled, the orthomosaic is rendered at the native resolution of the source images, so the finest details stay sharp when you zoom in. Worth switching on when image quality matters — processing takes roughly 1.5–2× as long (the time estimate reflects it) and, on large fields, the output file is considerably larger. The rendering runs block by block, so memory use stays bounded and HQ processing completes on large fields and on machines with less memory too. HQ projects carry a purple HQ badge in the project list.

Illumination balancing

When the Illumination balancing switch is on, the finished RGB orthomosaic is evened out for lighting changes during the flight — patches from passing clouds, a sinking sun — and for the brightness difference between outbound and return strips. The result is a calmer, more uniform base map.

It only affects the visual orthomosaic: the multispectral reflectance and the vegetation indices stay untouched, so NDVI / NDRE and anything built on them (AI analysis, application maps) are unchanged.

Starting the run

Two buttons at the bottom of the panel: Cancel closes the panel, Start process launches processing with the chosen settings. Above them, the panel shows the estimated processing time and disk usage for the current settings.

Processing time: a 100-image Mavic 3 M RTK RGB survey takes less than 40 seconds on an Intel i9 / 16 GB RAM / Windows machine (6 cm GSD), and less than 30 seconds on a Mac M4 / 24 GB RAM / macOS 26 machine (5 cm GSD); multispectral processing adds roughly 40-60% to the runtime.

The processing overlay

After launch, a translucent overlay appears on the map with the phase indicator:

┌────────────────────────────────────────┐
│  ⚙ Position refinement is running…     │
│                                          │
│  ████████████░░░░░░░░░░░░░░░ 62%       │
│                                          │
│  Elapsed: 4 m 12 s                       │
└────────────────────────────────────────┘

The phases in order:

1. Image analysis — reading image metadata
2. Tie-point search — finding matching points between image pairs
3. Position refinement — pixel-precise optimisation
4. Surface model — building the terrain grid
5. Render preparation — assembling the texture mosaic
6. Orthomosaic render — the final orthorectified image
7. Multispectral bands (if requested) — G, R, RE, NIR band orthos
8. Done — saving outputs

The Cancel processing button stops processing at the end of the current phase — partial results remain, but later phases don’t run.

Tips for best results

• Keep the Mac cool — long jobs (15+ minutes) can throttle the M3 thermally. An open desk, cool surface, and a stand all help.
• Close other applications — particularly memory-hungry Adobe apps.
• Use NVMe SSDs — faster intermediate writes save lots of time.
• 24+ GB RAM is recommended for 500+ image projects.

What do you get at the end?

The map automatically shows the fresh layers:

• Orthomosaic — RGB orthorectified image
• DSM — surface model shown as a colour heat map (blue → green → yellow → red, low to high)
• MS index — NDVI, GNDVI, NDRE, EVI, VARI (if multispectral processing was on)
• Flight path (green line)

The right-hand Project info panel gets fresh figures:

• Average GSD (precise value from processing)
• Accuracy — based on RTK statistics
• Area — precise hectare value

Reprocessing

The Process button can be hit again on the same project:

• New settings (different GSD, other switches) overwrite the old results
• Credits are not consumed again — a project licence is spent once, then unlimited reruns

Where the results are stored

Processing writes its results into the project’s Layers/ folder: the orthomosaic (<project>.tif + .tfw), the DSM heat map (dsm_ortho.png + .pgw), the multispectral band files (band_*.tif) and the 3D terrain data. The Exports/ folder holds only the files you export (index maps, shapefiles, application maps, reports, videos).

To reclaim disk space, use the Clean Up tab in Settings: choose a date under Older than: and either Delete ortho/MS files (removes only the orthomosaic and multispectral band files — the DSM, point cloud, boundaries, images and flight route stay, and the project can be reprocessed) or Delete old projects (removes whole project folders). Deletion cannot be undone.