Application map (VRA)

The application map (VRA = Variable Rate Application) divides the field into zones with a different application rate in each: fertiliser, herbicide, plant-protection product. DroneField builds one from your vegetation index in just a few clicks.

What it’s for

The core idea of precision agriculture: apply more where the plants need it, and less or none where they don’t. Typical applications:

Nitrogen fertilisation — more N to weaker stands
Herbicide — only where weeds are (Spot Spraying)
Seeding — for row-crops on heterogeneous fields
Soil-sample zoning — split the field into NDVI-similar zones to plan where to sample

Starting

Processing must have finished — at least the vegetation index needs to be available.
Draw (or import) a field boundary — this defines the application grid’s outer contour.
Select the field boundary, then click Application on the boundary toolbar.

A new panel opens at the bottom-left of the window: Application map. The plan is always built for the selected field — in a multi-field project, select the other field and click Application again to plan it (an open plan of another field is rebuilt for the new selection).

The application map panel

The panel is organised into three sections — Grid, Buffers and Zoning by — followed by the zone table.

Grid settings

Rotation — a slider from −90° to +90°. When the plan opens, the grid is automatically aligned to the field’s longest edge; adjust it if your passes run in another direction.
Grid size — one cell’s edge length, a slider from 2 to 10 m in 0.1 m steps; default 8 m. Smaller cells are more detailed but produce more cells; larger cells are coarser. Pick a size your drone or machine supports.
Zoning settings — the Pixel filter and Min. valid share (Mean index) or the Live threshold (Living share) sit under the Zoning by switch. See Pixel filter and Min. valid share.
Edge buffer — how far the DJI / XAG prescription extends beyond the field edge. See Edge buffer.
Zone buffer — widens the treated zones into the untreated zone. See Zone buffer.

The Generating grid… progress bar shows when the panel is rezoning the field.

Coverage to the field edge

The grid reaches the field boundary: a cell is part of the plan if any part of it lies inside the field. Edge cells therefore overhang the boundary as whole squares.

This is intentional — it is shown like that on the map and goes into every export (DJI, XAG, Hardi, ABZ, PNG / JPEG) the same way. The drone’s or sprayer’s own boundary trims the spray at the field edge. Using only cells whose centre is inside the field would leave an untreated strip of up to half a cell (up to 4 m with an 8 m grid) along slanted edges — and most spray drones do not spray where the prescription is empty.

Areas and product totals count only the part of each edge cell that lies inside the field — the field area does not grow.
Edge cells take their index value only from the pixels inside the field, so a neighbouring field, road or tree line does not pull them into the wrong zone.

Edge buffer

Choices: Off, 1 cell, 2 cells, 3 cells — default 1 cell.

When you export a DJI VRA precision map or an XAG VRA precision map, the prescription is extended beyond the field edge by this many cells; the extra cells copy the dose of the neighbouring edge cell. This way the outermost strip is sprayed even if the drone’s flight boundary is set exactly on the field edge.

The edge buffer does not change the area / product totals, the boundary file exported alongside (DJI boundary Shapefile, XAG field border) or the other export formats. If the outermost strip still comes out unsprayed, increase it. The setting is saved with the project.

On the map the extra cells are drawn dashed and faded in their zone’s colour, so you can see how far the prescription reaches; they do not count in the area and product totals.

Zone buffer

A slider from 0 to 20 m — default off (0). The label shows the effective value, e.g. 5 m → ≈ 8 m (1 cell): the distance is rounded up to whole grid cells.

Every treated zone (dose > 0) is widened into the untreated (0 l/ha) zone by this distance, so small patches that fall between two spray passes are still reached. A good starting value is about half the swath width of your sprayer.

It never changes the dose of a cell that is already treated; where two treated zones compete for the same cell, the lower dose wins.
Small isolated treated patches (1–2 cells) are kept while the zone buffer is on — normally they are merged into their surroundings, but these are exactly the spots the buffer should reach.
The zone buffer changes the zoning itself: the map, the area / product totals and all exports change accordingly.
Saved with the project; older projects open with the zone buffer off.

	Edge buffer	Zone buffer
What it widens	the whole plan, beyond the field edge	treated zones into the untreated zone
Visible on the map	yes, dashed	yes
Changes areas / product	no	yes
Exports affected	DJI and XAG VRA only	all
Default	1 cell	off

Above the zone table, choose how the cells are ranked:

	Mean index	Living share
A cell’s value	average index of its pixels within the pixel filter	% of the cell’s area above the live threshold (alive)
Zone bands	index values (e.g. 0.30–0.45)	percentages (e.g. 30–60 %)
Best for	fertilising, foliar feeding in a closed canopy	desiccation, weed-patch treatment

Why it matters: a cell that is 30 % fully green and 70 % dead and a cell that is evenly half-dry have about the same mean index — but for desiccation only the first one needs treatment. The living share tells them apart, no matter whether the green part is one patch or scattered. The AI analysis uses the living share for desiccation and weed-patch plans; with this switch you get the same logic in a manual plan.

Each basis keeps its own zone set: when you switch, the zones you leave are put aside and come back when you return. The first time, a starting set is offered with every dose at 0 l/ha — type your doses, adjust the bands or delete zones: Mean index offers 4 zones on the active index’s typical bands (the thresholds of the value guide table), Living share 3 zones — 50–100 %, 5–50 % and 0–5 %. With Mean index the zones are remembered per vegetation index: switching the index brings back that index’s own zones (or its starting set). With Living share a Live threshold row appears under the switch: a pixel at or above it counts as a living plant. By default it is automatic — computed from this field’s own pixels (Otsu: the valley between soil / dry residue and green plants), the same method the AI analysis uses as a fallback. Type a value to override it; ↺ returns to automatic. Cells with practically no living plant go to the untreated zone. An AI plan with an untreated zone opens with Living share already selected and its bands shown in %.

Under Zoning by: Mean index two settings decide which pixels count:

Pixel filter (min–max) — only pixels within this index range count in a cell’s average. Set the minimum above bare soil, for example, so the soil does not pull the average down. The filter belongs to the plan: the vegetation index panel’s display range only colours the map and no longer changes the plan. When you start a manual plan the filter starts from the current display range; the 🎨 button takes it over again at any time.
Min. valid share (default 60 %) — the share of a cell’s pixels that must fall inside the pixel filter:
- at least this — the cell is zoned by the average of its filtered pixels;
- below it, but at least a quarter of it (e.g. 15 % at 60 %) — the lowest treated zone (a partly living patch still gets a dose);
- less than that — the untreated (0 l/ha) zone.
The line under the slider shows these limits for the current value.

With Living share neither is used — the live threshold decides.

Zones

Manual zones work with bands: you set a min–max value per zone — an index value with Mean index, a percentage with Living share — and each grid cell lands in the zone whose band contains its value.

Each zone has:

Name and colour — assigned automatically (zona1, zona2 …, shades of blue); they cannot be edited
Dose — l/ha (liquid) or kg/ha (solid, seeds); the unit selector in the header shows one column at a time
Band — the min–max range of the zone; the column header is Index with Mean index and Live % with Living share
Σ amount and ha — the zone’s total product and area

How the bands behave:

A new plan starts with four zones on the active index’s typical bands (NDRE for example: 0.35–1, 0.2–0.35, 0.1–0.2, −1–0.1), every dose 0 l/ha. The lowest one is the “no treatment” zone — it always stays lowest, and it automatically receives the practically lifeless cells (bare soil, dried residue) as well.
Add zone inserts the new zone just above the lowest one by splitting the band above it — every value can be overwritten. A plan can have at most 10 zones.
Overlapping bands turn red, a gap between bands turns orange. The magic-wand button next to the field snaps the neighbouring zone’s band to yours — the value you typed is never lost.
If you edit the bands of an AI-generated plan (AI vegetation analysis), you take over manual control of the zoning.

The Total row at the bottom of the table sums the product amount and the area of all zones (overhanging edge cells count only with their part inside the field). The figures update live as you change the bands and doses.

Export

The panel’s Export menu (the share icon in the panel header) lists Save as PNG, Save as JPEG and the formats below. The To USB drive submenu offers the same items and writes straight to the drive you pick.

XAG Spot Spraying

A special XAG drone mode: the field is split into zones, and the drone sprays only the marked spots. Optimised path, less chemical.

Before export a confirmation dialog shows the final zone picture — click Yes to finalise. This confirmation appears for the XAG Spot, Hardi and ABZ exports only; it summarises per dose (colour + dose + area in hectares) instead of listing every polygon; the polygon count appears in a single summary row.

XAG VRA precision map

Conventional VRA: the drone sprays continuously, but the dose varies by zone. The prescription extends beyond the field edge by the Edge buffer setting (default 1 cell).

DJI VRA precision map

For DJI Agras T20 / T30 / T40 / T25 / T50 drones. Same principle as XAG VRA. DroneField creates the Exports/DJI/ sub-structure (Rx/ and ShapeFile/) — copy this to the USB root as-is. The files are named after the field (boundary) the plan belongs to — <FieldName>_Rx.tif / .tfw and <FieldName>_Boundary.shp — with accents removed and the name capped at 40 characters (a DJI limit). If the field has no name, the project name is used. The VRA export contains the boundary of the planned field only; for per-field boundary Shapefiles of a multi-field project use the boundary export. The Rx map extends beyond the field edge by the Edge buffer setting (default 1 cell); the boundary Shapefile stays exactly on the field edge. Details: Field boundaries → Exports/ folder layout.

⚠ Don’t export a standalone boundary KML for the same field when you’re shipping a VRA map — the Rx map’s companion Shapefile already includes the boundary, and the DJI controller would list the field twice.

Video guide: create a precision map and import it into the DJI T30 remote controller:

Hardi VRA Shapefile

The standard for Hardi and other large tractor sprayers in ESRI Shapefile format (WGS84). Loadable in any European farm-controller software (CCI 1200, Trimble, Müller).

ABZ Innovation (L-S series)

Exports the field boundary and — for variable-rate jobs — the prescription map (Rx) in the format that ABZ Innovation L-S series spray drones read.

Choose ABZ Innovation (L-S series) in the export menu.
Set an Output name for the export.

What you get:

A <Name>_Boundary folder — the field outline, with obstacles included as cut-outs.
For variable-rate jobs an <Name>_Rx folder with the prescription zones: each area carries one rate, areas don’t overlap, and the rest of the field is included as a zero-rate area.

Two things worth knowing:

Simple whole-field jobs: if the field has no variable-rate zones, the export contains only the boundary — you then set the payload and application parameters on the drone / controller.
No-spray zones are included in the prescription as zero-rate areas automatically.

Save as PNG / Save as JPEG

A visual image of the application map — for presentations, client emails.

Step-by-step workflow

A typical N-fertilisation workflow:

Survey — drone flies, M3M, ~5 cm/px (or 3–5 cm/px for NDVI), in good weather (overcast around midday).
Import + Processing — multispectral enabled.
NDRE map — switch to NDRE in the vegetation index panel (its display range only colours the map).
Field boundary — draw it or import the contour.
Application map — boundary toolbar’s Application button.
Pixel filter — on the application map panel, set e.g. 0.30–0.65 so bare soil does not pull the cell averages down.
Zones:
- Zone 1: 0.30–0.45 → 180 kg/ha (low — weak)
- Zone 2: 0.45–0.55 → 120 kg/ha (medium — average)
- Zone 3: 0.55–0.65 → 80 kg/ha (low — already healthy)
Export — DJI VRA precision map onto the tractor’s USB stick.

Tips

Match the grid size to your machine — the default 8 m suits most spray drones; go smaller only if the machine’s documentation supports it.
Don’t add too many zones — 3–5 is typical. Too many overcomplicate the operator’s job.
Always check the confirmation image (XAG Spot, Hardi, ABZ) — tiny zones (1–2 cells) or isolated dots are often noise; consider excluding them.

What NOT to do

Don’t rely solely on NDVI for N fertilisation of mature stands. NDRE is better.
Don’t use no-spray zones for dose marking — those are for drone-safety, not application.
Don’t forget to verify the export on the tractor / drone terminal — formats can be strict about encoding, and one wrong setting can ruin the run.

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