ScanAlign

ScanAlign is a Windows program for aligning 3D scans and turning them into something you can actually model from in CAD.

Aligning a 3D-scanned part is a nuisance. The scanner's own coordinate system has no idea which face is the bottom or which edge the dimensions come from, and the first fifteen minutes go into nothing but rotating the thing. And even then the result is usually just close enough! ScanAlign does it in a minute. You click the face on the model you want to align to, point out which side it is, and choose where the origin goes. The scan can be oriented from any number of features — an axis, a hole or a plane. The program rotates the part, and you export a straightened STL. At the same time you can create a wireframe mesh as a DXF file, already split into layers. Or have the program find the flat faces in the scan automatically.

All computation happens on your own machine. The program makes no network connection, uploads nothing to the cloud and sends your scans nowhere.

The program has two windows side by side: on the left the scan in its raw form, on the right the part in the position it will be exported in. Every change shows up in the right-hand window immediately, so you see the end result while you work.

DXF mesh. This feature traces the scanned surfaces automatically. You choose the axes and set how densely it slices — each axis has its own spacing, because a part is rarely the same thickness in every direction. Besides X, Y and Z you can click any face on the model and slice against it, along an angled flange for example. The curves are fitted to lines and arcs, so the DXF doesn't end up with a thousand points but a clean outline where the fillets are real arcs at the real radius. Each section is written to its own layer at its own height, so the stack is three-dimensional instead of collapsing onto a single plane.

Holes are found automatically. The program looks for circular features, draws them as true circles and adds a center axis line to each one. The radius is calculated from several sections together rather than a single slice, so it's more accurate than one read by eye. The flat faces of the part are found the same way the top of a plate, the bottom, lugs and drawn on their own layer at their own height, ready to be measured.

The export gives you STL and DXF, each selectable separately. Both come out of the same computation, so once exported they sit on top of each other in CAD with no extra alignment. Every choice you make is saved in a single project file, and the scan is stored inside that file, so moving the folder or renaming the file won't break the project.

Technical details

A Windows program; the interface opens in a browser on your own machine. STL in, STL and DXF out. Slicing directions X, Y and Z plus freely chosen planes, each with its own spacing. Fit tolerance 0.10 mm, adjustable. Handles scans up to 500,000 triangles; larger ones are decimated automatically. Package size 76 MB compressed, 215 MB extracted.

No installation, no login, no license server. The program brings its own Python runtime with it: you extract the folder and start it. Nothing is installed on the machine, nothing is left running in the background, and the program works on a machine with no network connection at all. You close the window when you're done.

To use it you need a Windows computer, a 3D scan in STL format and a CAD program to open the DXF/STL in.

Good to know

Automatic alignment is slow on a large scan — a couple of minutes on a 500,000-triangle model. A face you click by hand aligns in seconds, and that's also the way the program is meant to be used: you know which face is the part's alignment face, the program doesn't.

The section curves are open curves, not finished closed profiles. A scan is a surface, not a solid, so there are always places along the edge where there's no data. The curves are meant as anchor points for modeling, not to be extruded directly. The program also can't tell a protruding round boss from a hole — to it, both are cylinders.

License

Every copy purchased is licensed for the buyer's own use: use it on as many projects as you like, but don't share, sell or distribute the program. Respecting this directly supports independent development work and helps make tools like this possible in the future. Thank you!