When to use it
Auto Detect Symbols (scan drawing) reads a whole vector drawing in one pass and shows you every symbol that repeats on it, each as a thumbnail with a rough count. Tick the ones you want and ZeroCount counts them all in one go, creating a Detection group for each.
Use it at the start of a sheet, before you know what is on it. It answers "what is on this drawing and roughly how many of each" in a few seconds, and saves outlining a dozen symbols by hand. Once the obvious symbols are counted, go back to Detect New Symbol for anything the scan missed.
The scan only runs on vector drawings. On a scanned or flattened sheet there is no geometry to enumerate, so the tool refuses with a message rather than guessing.
Where it is
Open New Takeoff in the workspace header. Under Auto Takeoff, choose Auto Detect Symbols (scan drawing) .
The three items under Auto Takeoff are greyed out when the drawing cannot be scanned. Hover one to see why: No active file, Still checking this drawing, Rotate the file back to its uploaded orientation first, or Missing paper-size info for this file (legacy upload).
Running a scan
- 1
Choose New Takeoff › Auto Detect Symbols (scan drawing). The Auto-detect symbols window opens and reads Scanning drawing for symbols....
- 2
Wait for the grid of thumbnails to appear. Each cell is one symbol found on the sheet.
- 3
Click a thumbnail to tick it. A blue ring and a tick in the corner mark it as selected, and the count at the top of the grid reads N selected.
- 4
Use Select all to tick every top-level symbol, or None to clear the selection and start again.
- 5
Click Detect N symbols. The window closes and the drawing shows Detecting symbol 1 of N... as each one is searched.
Reading the grid
Each cell shows the symbol drawn on a white background, with two labels.
| What you see | What it means |
|---|---|
A plain number, e.g. 24 | An exact count. ZeroCount can see the symbol reused as a block in the drawing data. |
A number with a tilde, e.g. ~24 | An estimate. The symbol was recognised by its shape, so the real count after detection can differ by a few. |
legend | The symbol came from a legend rectangle you drew, not from counting repeats. |
A short code at the bottom left, e.g. EXT/1 | The name read from the legend row. The Detection group is named with it. |
+2 at the top right | This symbol absorbed two look-alike variants. |
The count on a cell is a guide for choosing, not the answer. The real count arrives when detection runs.
Merged variants
Drawings often put slightly different clutter inside each copy of a device — a wire crossing it, a ceiling grid tick, a leader line. Those used to appear as separate entries and fill the list with the same symbol over and over. ZeroCount now gathers them into one cell showing the full count.
Nothing is hidden. Click the +N button at the top right of a cell to open the variants out below it, shown with dashed borders. Each one can be ticked on its own, so if a merge looks wrong you can pick the exact variant you want instead of the parent.
What you get afterwards
- One Detection group per symbol you ticked, named Group 1, Group 2 and so on, or with the legend code when the symbol came from a legend.
- A toast reading Symbol scan complete with a summary, for example "Created 6 groups with 214 markers." It may add "N via standard detection.", "N already marked." or "N skipped."
- Symbols already marked on the drawing are not counted twice.
- If the drawing has AoIs, the scan locks and hides them before it starts, and only counts symbols inside them. See Areas of interest.
Scanning from a legend
If you have drawn a legend rectangle on the sheet, the scan reads the legend instead of hunting for repeats. It takes one candidate per legend row, names each one from the legend code, and searches the drawing once per row. The legend's own copy of each symbol is left out of the count, so the legend key does not inflate your totals.
The window says so at the top: Symbols read from the drawn legend, one per row. Detection runs once per selected symbol, exactly like Detect New Symbol.
This is the more reliable way to run a scan on a busy sheet, because the legend tells ZeroCount exactly what a symbol is and what it is called. See Drawing a legend.
If the rectangle turns out to hold nothing usable, the scan falls back to reading the whole drawing and says so in an amber notice: "No symbols were found inside the drawn legend, so the whole drawing was scanned instead. Check the legend rectangle covers the symbol column."
Limits of the list
The grid holds at most 60 symbols, so on a dense sheet the list keeps the strongest candidates and drops the rest. Two other rules shape it:
- A symbol has to appear at least twice. A one-off device never shows up in a whole-drawing scan.
- Lettering is pushed down the list. On drawings whose text is drawn as outlines rather than as text, a word repeated across the sheet looks much like a repeated symbol, so words now rank below real symbols.
If a symbol you expected is not listed, count it with Detect New Symbol instead.
Common issues
"Symbol scan unavailable"
Two reasons, and the message says which:
- This file is not a vector PDF. The drawing is a scan or a flattened export, so there is no geometry to enumerate. Count it with Auto Count Symbol instead.
- This file has no paper-size information. The drawing was uploaded before ZeroCount recorded paper size. Upload it again to fix this.
"No repeated symbols found on this drawing."
The scan finished but nothing repeated often enough, or clearly enough, to list. This is normal on a sheet that is mostly linework, or one whose symbols are drawn slightly differently each time. Draw a legend rectangle and scan again, or use Auto Count Symbol.
The same device ended up in two groups
Variants you ticked separately each get their own group. Merge them afterwards from the group row. See Merging groups.
Next steps
- Drawing a legend — draw a rectangle round the symbol key so the scan reads it one row at a time.
- Detect New Symbol — count anything the scan missed by outlining one example.
- Merging groups — join two groups that turned out to be the same device.
- Detection tips — what to change when results are patchy.
- Cleaning up the drawing — remove background linework that is confusing the scan.