Correction and scale
Make the photo measurable before anything is drawn.
Every line inherits the scale of the photo.
Correction happens before anything is drawn, and the scale you calibrate is locked into every traced line, every dimension and the final export. Measure traced geometry in inches or millimetres instantly; the DXF exports at 1:1.
The printable reference sheet is the fastest route: include it in the photo and perspective and scale are set in one tap, with the part cropped to the paper and the sheet's markers ignored by every trace method. About the reference sheet →
Lens, perspective, scale, and the photo itself.
- Lens correction. LensCAD reads the camera and lens from the photo's metadata and removes barrel and pincushion distortion from the Lensfun profile database, a custom Charuco calibration you shoot yourself, or the phone's own pre-corrected output.
- Perspective correction. Four modes: click four corners, align two perpendicular lines, fit a circle or ellipse, or use the reference sheet for one-tap correction to a true orthographic view.
- Scale calibration. A known dimension of the selection, a ruler in frame, dual rulers for independent X and Y, or the reference sheet's automatic scale.
- Precision loupe. A magnifier with snap indicators, guide intersections and live brightness preview, for pixel-accurate point placement on a phone.
- Crop, straighten, rotate. Square up a photo taken slightly off, crop to the part, or turn a view a quarter turn. Whatever you have already traced moves with the pixels rather than being thrown away.
- Multi-view. Photograph all sides of a part, process each view independently, export one DXF as a proper third-angle projection, or build a 3D model. Up to six orthographic views, with an illustrated guide in the app showing how to lay each one out. A symmetric part can mirror one side onto the other, drawing and photo included, instead of being photographed twice.
- Views that agree on the part. A later view can take its scale from the first, and once both are drawn LensCAD measures it again from the dimension the two views share, so the part is the same size in every view. Check views shows how each view reads the part and flags a disagreement; Match fixes it against the view you trust, and Revert last Match puts the scales back if it made things worse.
- Straight from the phone. HEIC photos from an iPhone upload as they are, and a 12 MP frame arrives at full resolution instead of being shrunk on the way up. The corrected image is built at the photo's own resolution, never at a fixed size.
- Privacy before storage. Before a photo is kept, its location, timestamp and serial-number metadata are stripped. Faces are not blurred, so keep people out of the frame. Your photos and drawings are never used to train a model. Trust center →
Each method, and when to use it.
Four cornersAny flat rectangular thing
Tap the four corners of a rectangle you know is a rectangle: a door, a panel, a sheet of paper. LensCAD warps the photo so those corners become a true rectangle. Combine with a known width or height for scale. The loupe helps you land each corner on a phone.
Two perpendicular linesWhen there is no full rectangle in frame
Draw two lines you know meet at a right angle, such as the edges of a strap hinge. Enough to remove keystoning from a flat part without a rectangle around it.
Circle or ellipseRound parts photographed at an angle
Fit an ellipse to a circle you know is round, such as a hole or a flange, and the photo is corrected until it is. Scale from the circle's diameter.
Reference sheetOne tap for perspective and scale
Print the free sheet (a small card for small parts, Letter, Tabloid or a large format), put the part on it, photograph it. The four printed markers give perspective and scale together; the crop covers the paper, not just the markers, and the sheet's furniture is ignored by every trace method. The UI names the page it recognised and lets you override a custom sheet size. If glare, a fold or the part itself hides a marker, place the four corners by hand and the result is exactly as if they had been read. Download and details →
Scale methodsKnown dimension, ruler, dual rulers, reference sheet
Edge dimensions: type the width or height of the corrected selection. Ruler: mark two points on a ruler or tape measure in the photo and type the distance. Dual rulers: the same in X and in Y independently, for a photo whose correction left the axes slightly different. Reference sheet: automatic, from the marker spacing.