The two-line summary
- AOI = Area of Interest. Tells the detection pipeline where to search. Used in Stage 1.
- Zone = Output filter. Tells the Excel export how to split totals. Used in Stage 3.
They look almost identical on the canvas — both are coloured polygons. They're stored in the same dropdown — see Zones & AOIs panel. But they do nothing alike.
What an AOI does
When you press Submit in Stage 1, ZeroCount only searches for symbols inside the AOIs. Anywhere outside is ignored.
So AOIs:
- Filter the detection input. No detection happens outside an AOI.
- Speed things up. Smaller AOIs mean faster pipeline runs.
- Exclude legends. A correctly-placed AOI doesn't cover the legend, so the legend symbols aren't double-counted.
AOIs don't appear in the Excel export. Once Stage 1 is done, they've done their job — though they're still visible on the canvas and you can edit them if you want to re-run detection later.
See AOIs and Manual AOIs.
What a zone does
A zone is a polygon you draw on the drawing that groups markers by where they sit. Each marker falling inside a zone gets counted in that zone's column of the Excel export.
So zones:
- Split totals by region. One column per zone in the export.
- Don't affect detection. They exist purely for the export.
- Clip Linear and Area measurements. A Linear marker that crosses a zone boundary is split — the inside-zone portion counts in that zone, the rest goes to "Uncategorized".
Without zones, the export has a single All column lumping everything together.
See Zones.
The same drawing, both at once
Most real projects use both — but for different things.
A lighting layout on a building:
- AOIs = the working part of the drawing (the floor plan itself, excluding the legend and title block). One large polygon, or a couple if the floor plan is in two pieces.
- Zones = rooms, areas, levels (
Office 1,Office 2,Kitchen,Stairwell A, etc.). Many polygons, one per region you want totals split into.
They overlap geographically — every zone sits inside the AOI — but they do different things in the pipeline.
A quick test
If you're not sure which to draw, ask:
| Question | Answer |
|---|---|
| Do I want this polygon to affect what ZeroCount detects? | AOI |
| Do I want this polygon to split the export by room or area? | Zone |
| Do I want both? | Draw an AOI and a zone (they can occupy the same space) |
| Neither? | Skip — you don't need either |
Common mistakes
- Using an AOI as a zone. You won't see counts split in the export. AOIs don't appear there.
- Using a zone as an AOI. Detection won't be constrained — every symbol on the whole drawing gets scanned, including the legend.
- Skipping AOIs entirely. Stage 1 still asks for them — without one, Submit doesn't work.
- Skipping zones when totals need splitting. Easy to forget until you see the export with a single
Allcolumn.