In short
A vector PDF from CAD still contains the drawing as lines: every wall is a stroke or a filled band with exact coordinates on the page. The browser reads those lines before the plan is sent for reading and hands them over as a second input, so wall positions come from the file rather than from an interpretation of pixels. A scan or a photo has no lines, only pixels; the reading works from the image alone and needs more correction. Both work; the vector file simply starts closer to the finished model.
Two kinds of PDF that look the same
On screen a scanned plan and a CAD export look alike. Zoom in and the difference shows: the scan turns into grey squares, the vector export stays sharp at any magnification, and the text can be selected with the mouse.
That is the whole difference in one sentence: one file still knows where its lines are, the other only knows which pixels are dark.
What the browser reads from a vector page
Thick strokes
Walls drawn as a single heavy line become a wall centreline with the stroke width as thickness.
Filled bands
Walls drawn as filled rectangles or polygons become a centreline with the band width as thickness.
Pairs of thin parallel lines
The classic CAD wall with hatching between two outlines: the pair becomes one wall, the spacing its thickness.
Why a second input matters
Reading a plan from pixels means deciding, for every dark line, whether it is a wall, a dimension line, a hatch or a piece of furniture. That decision is usually right and sometimes not, and every wrong decision is a correction in the editor.
With the vector candidates alongside, wall positions are given and the reading concentrates on what the lines cannot say: which opening is a door, where a room ends, what the labels mean. The list holds up to 120 walls, longest first, in the same coordinate frame the reading uses, which covers any single storey of a house or an apartment block. Reading costs one point per storey either way; the vector step adds nothing.
What scans and photos deliver
Scan at 300 dpi
Fine for most plans. Faint dimension lines and title blocks over the drawing cause most corrections.
Photo of a paper plan
Works, with distortion. Shoot from straight above, even light, whole sheet in frame.
Scanned PDF
A PDF with a picture inside. The vector step finds nothing and the page is read as an image, exactly like a JPG.
How to export the better file
- 01Print to PDF from CADUse the PDF export or PDF printer of your CAD programme, not a screenshot. Keep the drawing as vectors; do not rasterise. Sheet size does not matter, A3 and A0 read alike.
- 02One storey per pageEach storey on its own page. The reading takes one page at a time and assigns it to a storey.
- 03Leave the dimensions inDimension chains set the scale. Without them the scale is estimated from a door leaf of 0.90 m or a bathtub of 1.70 m, with a warning.
- 04Crop the title block if you canLess text on the page, fewer things to misread, and no client name in the upload.
Questions and answers
Does a vector PDF cost extra?
No. The lines are read in the browser before upload, at no charge. Plan reading costs one point per storey with any file type.
Is my CAD export a vector PDF?
Open it and try to select a text label with the mouse. If it highlights, the page is vectors. If not, it is a scan or a rasterised export.
What about DWG or DXF?
Not directly. Export the storey to PDF from your CAD programme; that keeps the vectors and works today.
Does the vector step replace the check?
No. Walls still need a closed outline and openings still need a wall. The check before building runs on both kinds of file.
