AlignScan / Guides / Why scans are tilted
Guide
Why is my 3D scan tilted?
Almost every raw scan arrives tilted, and it is not a mistake: a scanner has no idea which way is "up" for your object. It simply starts a coordinate system and builds the mesh in it.
Where the tilt comes from
- The first frame defines the axes. Handheld and structured-light scanners usually anchor the coordinate system to wherever the scanner was pointing when scanning began. If the first view was a bit off-axis, the whole scan is.
- Turntable and marker setups drift. The turntable plane or marker sheet gives a horizontal reference only if it was level, and only if the software uses it.
- Photogrammetry has no gravity at all. Camera positions are recovered up to an arbitrary rotation, so the result can be at any angle.
- Several scans merged together inherit the pose of the reference scan they were registered to.
- Cleanup tools do not re-level. Filling holes or smoothing keeps the original pose.
Why it matters
A tilt of a few degrees looks harmless while orbiting but breaks the things you do next: sketching on a face in CAD, cutting along a plane, placing the part on a build plate, measuring along an axis, or exporting to a game engine. Fixing it early saves effort in every later step.
How to fix it properly
- Find a datum. On mechanical parts it is a large flat face, a wall or a bore axis. On organic shapes it is a symmetry plane or the principal axes.
- Measure it instead of eyeballing. Plane fits average thousands of vertices, so they ignore scan noise that fools the eye.
- Rotate the mesh itself, not just the object transform, so exported files stay square.
- Recenter and choose Z-up or Y-up for your next tool.
Skip the manual work: drop your scan into AlignScan. It runs in your browser and the file is never uploaded.
Open the aligner → Try a sample firstWhat if it still looks off?
Check which faces were locked: if the scan is partial or has no flat regions, the result is approximate, and good tools say so. Manual mode lets you click a face you trust and snap it to an axis or the floor.