ALIGNSCAN

Free · No upload · No sign-up

Align a 3D scan to the world axes

Drop an STL, OBJ or PLY. Flat faces and cylinder axes snap square to X, Y and Z with the smallest possible rotation, and you see exactly what it locked onto.

Your file stays on this device. It is read, analysed and re-exported in your browser. No scan to hand? (a crooked, noisy bracket).

How it works

  1. Drop the file

    STL (binary or ASCII), OBJ or PLY. Parsing and analysis run in a background thread, so the page never freezes, even on 100 MB scans.

  2. It finds what is flat

    Local plane fits over the whole mesh cut through scan noise. The dominant faces, cylinder axes and fillets become the reference frame.

  3. It squares the scan

    The frame snaps to X, Y and Z by the smallest rotation from where the scan already sits. Download the same mesh, rotated.

Built for scans, not clean CAD

Raw scans arrive at a random angle: whatever way the scanner or turntable happened to face. Aligning by eye in a mesh editor is slow and never exact. AlignScan measures the orientation of the flat walls, ribs and mounting faces in your scan, then rotates the whole mesh so they sit parallel to the world axes.

What it locks onto

  • Flat faces found by robust plane fitting, so they hold up against noise.
  • Cylinder and fillet axes: holes, shafts, rounded edges.
  • Outline edges when only a single flat face is visible, such as a plate scanned from above.
  • Mirror symmetry and principal axes as a fallback for organic shapes with no flats. Confidence drops and the tool tells you so.

Manual mode for the awkward ones

Click a few points on any face. AlignScan region-grows the face, fits a plane with outlier rejection and snaps its normal to an axis or to the floor. Click a second face to lock the remaining spin. Undo is one keystroke away.

Recenter, flip, and export for your tool

Move the bounding-box centre or surface centroid to the origin, sit the part on Z = 0, rotate by 90° steps, and export Z-up or Y-up. The applied rotation is shown in degrees and as a matrix. Read the guide to zeroing a scan's rotation.

Privacy by architecture

There is no upload endpoint. The site is static files, and its content security policy forbids network requests to anywhere but its own host. See Privacy.

Guides

FAQ

Are my files uploaded?
No. The file is read locally, analysed in a Web Worker and exported locally. There is no server that could receive it.
How does the automatic alignment work?
It fits planes to flat regions, finds the dominant directions, adds cylinder and fillet axes, and solves for the rotation that squares them to X, Y and Z. Among equivalent solutions it picks the smallest rotation from the current pose. For shapes with no flats it uses mirror symmetry or principal axes and reports lower confidence.
Which formats and sizes does it support?
Binary and ASCII STL, OBJ and PLY (ASCII and binary). Scans of 100 MB and several million triangles are routine. Very large files are limited by your browser's memory.
How accurate is it?
For parts with flat faces, the locked faces typically land within 0.1–0.5° of the axes. That was measured with an independent plane detector on 58 real files and on more than 1,100 synthetic scans with a known pose. Very noisy or partial scans and shapes with no flat faces are harder, so every result shows what it locked onto and a confidence label (high, medium or low). Anything below high deserves a glance in the Top and Front views.
Does the export change my mesh?
Only vertex coordinates and normals are transformed. Triangle count, order and topology are untouched, and other file contents (comments, colours, attributes) are kept.
It picked the wrong way up. What now?
Use the rotate and flip buttons, or switch to Manual and snap a face to the floor. Everything is undoable.
Is it really free?
Yes. The site is supported by affiliate links shown after you download a file. See the disclosure.