Keystoning

Keystoning is for flat surfaces. When the projection target is a wall, a screen, a piece of plywood, or anything else with a single plane, you don’t need to import a mesh and warp vertices — drop four corners on the four corners of the flat surface and the math falls out.

If your surface is curved, sculpted, or non-planar, use warping instead.

When to use keystone vs warp

Use keystone when	Use warp when
Surface is flat (wall, screen, plywood)	Surface has curvature, sculpting, or 3D structure
You just need it to land square	You need surface-following alignment
Speed matters more than precision detail	Detail and surface fidelity matter
Single planar correction is enough	Multiple alignment regions on one surface

The two tools coexist — you can keystone first to get the rough alignment, then add a mesh warp on top for any leftover surface variation. Most flat installs never need the warp layer.

Adding a keystone

Select the projector in the Projectors panel, then open the Keystone tool. The four corner handles appear over the live preview — drag each handle to the corresponding physical corner of the surface.

The handles are sub-pixel: you can drag with the mouse for rough alignment, then use arrow keys for fine adjustment. Arrow keys nudge the active corner by one pixel; hold shift to nudge by ten.

Aspect-ratio lock

The keystone has an aspect-ratio lock toggle. When enabled, dragging one corner preserves the projector’s native frame aspect ratio — the other corners adjust to keep the math consistent.

This is helpful when:

• You want to keep the projected image proportionally correct, just trapezoidally placed
• The surface is rectangular and you don’t want the image to skew

It’s not helpful when:

• The surface itself has a non-rectangular shape
• You actually want the projection to fill an irregular flat region

Snap to projector ratio

The Snap to projector ratio button resets the keystone to the projector’s native frame (no correction). Useful as a “I screwed this up, start over” button — one click and you’re back to the projector’s natural output.

Saved per projector

Like warps, keystones save per projector. Each projector has its own keystone correction stored as part of the projector entity, not the scene. The same keystone applies regardless of which scene is playing — keystone is physical-alignment data.

This means once you’ve keystoned the projectors during install, you don’t touch them again unless the physical setup changes. The keystones travel with the project file when you save.

Combined keystone + warp

If you’ve keystoned a projector and then add a mesh warp, the warp is applied after the keystone — the keystone is part of the projector’s “natural” output as far as the warp tool is concerned.

You can edit either independently. Adjusting the keystone doesn’t reset the warp, and adjusting the warp doesn’t unbind the keystone.

Collaboration

Keystone editing acquires a lock on the projector, same as warping. Another operator selecting the same projector to edit its keystone will see a read-only view until you release the lock or hand it over via Request Access.

Related

• Warping workflow — for non-planar surfaces
• Projectors — what the projector entity owns