Getting soundings out of a dredging survey PDF
Bidding a dredging job usually starts with a condition survey: a before-dredge (pre-dredge) or after-dredge (post-dredge) sheet of a navigation channel, harbor, port, marina, river or reservoir, covered in hundreds or thousands of spot depths. The sheet arrives as a PDF, but your estimate needs those depths as data. You need points you can load into Civil 3D, HYPACK, QGIS or a spreadsheet to work out dredge quantities, cut and fill volumes, or where shoaling has built up.
The usual way to get them is slow. Someone opens the PDF in CAD and traces or retypes each sounding, often for a full day per sheet, then checks the work for typos. The numbers are already in the file. They just aren't in a form your software can use.
What ensoundings does
ensoundings reads the depths straight out of the PDF and gives them back as a CSV, one row per sounding:
Example rows, in the real format.
- Easting and northing
- Georeferenced from the coordinate grid printed on the sheet itself, such as border labels like E 875,000 or X=486000. The values stay in that grid's own system and units, whether that's state plane, UTM or a local grid, exactly as labelled. Nothing is converted or reprojected.
- Depth
- The number as printed, in the sheet's own units and relative to its own datum, such as MLLW, MLW, NAVD88 or chart datum. No rounding, no sign change, no conversion.
- Confidence
- How clear the reading was, from 0 to 1. Points that need a second look are flagged for you to check.
If a sheet has no coordinate grid the reader can use, the file says so. It then gives positions on the page instead of real-world coordinates, and never presents those as eastings and northings.
The CSV opens directly in Excel, so this is a PDF-to-Excel step as well, and it imports as points into AutoCAD, Civil 3D, ArcGIS, QGIS or HYPACK.
Where these sheets come from
Public owners such as the U.S. Army Corps of Engineers (USACE), port authorities and their consultants often issue condition surveys as PDF plan sheets. Whether a particular sheet reads well depends on how it was produced, not on who issued it, so the reliable answer is to check your own sheet. That's free.
Will it work on your sheet?
Honestly, it depends on how the PDF was made. The quickest way to find out is to try it: you see every sounding it found, laid over your sheet, before you pay anything. A sheet it can't read costs nothing.
Most likely to work
- One-page vector PDFs exported from CAD or GIS. These are the “original” PDFs, not scans.
- Depths printed as decimal numbers next to their marks, such as 17.1 or 9.8, whether typed as text or drawn as line work.
- A coordinate grid labelled around the border.
- One sheet at a time. From a plan set with several sheets, you pick the sheet to convert, and you can outline just the soundings on it.
Not supported yet
- Scanned or photographed sheets, or any PDF that is just an image of a drawing.
- Depths shown only as contour lines (isobaths) or shaded bands. On the roadmap.
- Depths written as whole numbers with no decimal. On the roadmap.
- Very large or very dense drawings. If one can't be processed, you're told why and charged nothing.
How it works
- Upload a vector PDF and pick the sheet to convert from the window that opens. To read only part of it, click around the soundings to outline them; otherwise the whole sheet is read.
- Review the result: the number of soundings, the overall confidence, and every flagged point. No account is needed.
- Pay and download once you're happy: $75 per sheet, or less with a monthly plan. You get the CSV immediately and can download it again any time within 18 months.
Your PDF is used to make the conversion and isn't kept afterwards.
Before you rely on it
The CSV is a reading of a drawing, not a new survey. It can only be as accurate as the sheet it came from, and an automatic reader can miss or misread a sounding. That's why every point carries a confidence score and why the review step exists. For estimating and checking, verify against the source sheet. Before using the data for anything where depth is a safety matter, or as the basis of a bid or design, have a licensed surveyor check it.
Try it on your sheet
Upload a sheet and see what it reads before you pay anything.