Blenspy matches a Blender camera to a photograph, right inside Blender. Drop in a reference photo, and Blenspy finds the vanishing lines, solves the camera, and opens it with your photo as the background, ready to model through.

What it does

• Automatic calibration. Detects straight edges, finds the vanishing directions, and solves focal length and camera orientation. It works best on architecture and interiors.
• Editable guides. Turn on Edit Guides to drag the detected lines onto edges that are parallel in the real scene. Axes are color coded (X red, Y green, Z blue). Shift slows a drag, Ctrl+Z undoes it.
• Lens hints from EXIF. Uses 35 mm equivalent focal lengths from your photo's EXIF data, scaled to the sensor you pick. Supports principal point shift for cropped photos and optional lens correction.
• Real world scale. Set a known distance under Scale when physical dimensions matter.
• Draw Plane. Click around a floor or wall in the photo and Blenspy projects the outline onto the matching world plane, giving you a real, filled mesh that lines up in camera view. Supports quads and n-gons, with Floor (XY), Wall (XZ), Wall (YZ) and Camera Facing modes.
• Modeling guides. Add floor and wall wireframe planes, or a grid and cube, aligned to the matched origin as orientation scaffolds for modeling. Hidden from renders by default.
• Save and share projects. Save .rhn project files with your guides, camera and embedded image, or export .fspy for importers that read the fSpy format.

Compatibility

• Blender 4.2 and later: install blenspy.zip from Preferences > Get Extensions > Install from Disk.
• Blender 3.5 to 4.1: install blenspy-legacy.zip from Preferences > Add-ons > Install.
• Tested on Windows with Blender 3.5.1, 4.2.4 LTS and 5.2.0 LTS. Newer versions are allowed by the extension but not yet tested.

Find it in the N sidebar of the 3D View or Image Editor under the Blenspy tab.

Good to know

• A single photo can't tell you absolute scale, so set a known distance if you need real dimensions.
• Organic scenes, panoramas, heavy lens distortion and narrow telephoto shots may need guides placed by hand.
• One-point perspective photos rely on EXIF or a lens estimate for focal length, and Blenspy tells you when it does.
• If an automatic solve fails, your previous guides and camera are kept.

License

GPL-3.0-or-later. Blenspy is an independent Null Station add-on. It reads and writes the fSpy file format but is not affiliated with or endorsed by fSpy or the Blender Foundation.

More at nullstation.co