Two kinds of PDF
Every PDF you upload is one of two things, and it decides how fast and how exactly ZeroCount can count on it.
A vector drawing came straight out of CAD. The PDF still holds the drawing as geometry: this line runs from here to there, this symbol is placed at this point and turned by this angle. ZeroCount can read that geometry directly, so a symbol search is exact and effectively instant.
An image drawing is only pixels. A scan, a photocopy, a flattened export or a converted DWG all end up this way. There is no geometry left to read, so ZeroCount matches the picture of your symbol against the picture of the drawing. That works well, but it takes a few seconds per symbol rather than being instant, and it is more sensitive to how tightly you draw the box.
You do not have to choose anything for this to work. ZeroCount classifies each drawing when you upload it and uses the right approach automatically.
Telling which one you have
Every drawing card and row on the project page carries a small badge reading vector or image, with a green dot when vector features are active and a muted dot when they are not.
Click the badge for a read-only popover explaining that drawing. Its title is one of three:
| Title | What it means |
|---|---|
| Vector detection | The richest case. The PDF places its symbols as reusable pieces, so ZeroCount can read the symbols themselves. The popover also gives a count of symbol candidates and placements found. |
| Vector symbol search | The drawing has vector artwork, but its symbols have been flattened into raw lines. Symbol search still runs on the geometry. |
| Image detection | The drawing is pixels only. |
The reason line underneath spells the same thing out in words:
- "Symbols are read directly from the PDF drawing data — exact positions and rotations, no scan time."
- "Symbol search (Detect New Symbol) reads this drawing's vector data — exact instance matching, no scan time. Auto Takeoff uses the standard image detector (the symbols are flattened into raw paths)."
- "This drawing is image-based (scanned or converted) — the standard image detector is used."
A PDF that has only just been uploaded may show no badge for a moment while it is being classified.
The detection engine button
Once a drawing is open, the same information sits at the far left of the workspace toolbar as a single icon button:
| Button | Meaning |
|---|---|
| A vector engine is in use for this drawing. | |
| The image detector is in use. |
Hover it for a three-line tooltip: the engine name in bold, the reason above, and, when a swap is possible, a hint reading "Click to use image detection" or "Click to use vector detection".
On a drawing that cannot swap, the button is dimmed but the tooltip still works, so you can always read why.
Switching a drawing to image detection and back
- 1
Open the drawing.
- 2
Click the detection engine button at the left of the toolbar. It changes to and the drawing now uses the image detector.
- 3
Click it again to return to vector detection.
The choice applies to that one drawing, not the project, and it is remembered in your browser. Other people working on the same drawing are not affected.
Reach for this when a vector search on a drawing keeps returning fewer instances than you can see. Some CAD exports draw what looks like one symbol as several unrelated pieces, and the image detector, which only looks at the picture, can do better on those. It is worth a try before you resort to counting by hand.
What still uses the image detector on a vector drawing
On a Vector symbol search drawing the symbols have been flattened, so:
- Auto Count Symbol and the symbol scan read the geometry and stay exact.
- Auto Takeoff work falls to the standard image detector, because there are no reusable symbol definitions left to read.
This is normal and needs nothing from you. The popover and the tooltip both say so.
Two other things are the same whichever kind of drawing you have. Auto Detect Symbols (scan drawing) needs a vector PDF and tells you when it cannot run: "Symbol scan unavailable" — "This file is not a vector PDF." And Remove Background and ignored colours hide ink from every detector, so anything you have cleaned away is invisible to a capture on both kinds of drawing. See Cleaning up the drawing.
When the app falls back on its own
Even on a vector drawing, a particular capture may not be something the vector matcher can work with. When that happens ZeroCount runs the image detector for that capture instead of failing, and you carry on.
Sometimes it tells you, with a "Using standard detection" message:
- "Vector search wasn't possible for this selection — running the standard detector."
- "No reusable vector symbols found — running the standard detector instead."
- "Vector detection was not possible for this file — running the standard detector instead."
More often it is silent, because the result is the same either way. The usual causes are a capture that is mostly lettering, a mark with too few strokes to describe, or a box with no vector ink under it at all.
If the box was genuinely empty you get a different message: "Blank Template Detected" — "The selected region appears to be blank. Please try again with a region that contains a symbol."
Common issues
An image drawing feels slow
The first count on an image drawing takes a few seconds while the drawing is prepared on the server; later counts on the same drawing are quicker. The Auto Takeoff section of the New Takeoff menu says so directly, with the note "Image drawing — first detection takes a few seconds".
Auto Detect Symbols is missing or refuses to run
It is only offered on vector drawings, and it also needs the drawing's paper size, which very old uploads may lack. Re-uploading the PDF fixes the second case.
The badge says vector but nothing seems exact
Check the toolbar button. If it shows then the image detector has been selected for this drawing, either by you or by someone using this browser before. Click it to switch back.
Next steps
- Ways to count symbols — which counting tool to reach for.
- Auto Count Symbol — counting from one example.
- Auto Detect Symbols (scan drawing) — scanning a whole vector drawing at once.
- Drawing cards and badges — the other badges on a drawing card.