by LongLiveTheCube·Modeling
Images © LongLiveTheCube. Used for product review; image policy.
img2cube earns its place in the Blender extensions library for handling camera matching entirely inside Blender, with no external app in the loop.
img2cube is a free camera-matching extension for Blender from LongLiveTheCube. Starting from a photo, you draw lines along edges that are parallel in real life, then click Solve. The solver recovers focal length, rotation, and principal point using SVD. You can run a 2-VP solve for a quick result or a 3-VP solve for higher accuracy, with the residual reported in pixels as precision feedback.
Enter one known real-world measurement, such as a door height, and the whole scene rescales to match. A depth graph propagates measured lengths through connected segments via BFS, including across T-junctions, so unmeasured segments get 3D lengths automatically. Clicking any drawn line or extension places a Blender Empty at the computed 3D position, and snap points auto-snap to line intersections for precise placement.
The extension works entirely inside Blender with no external app, using only numpy and mathutils, both shipped with Blender. Version 1.0.6 supports Blender 4.2 LTS and newer and is released under GPL-3.0-or-later.
img2cube is best for blender artists reconstructing buildings or scenes from reference photos who need the camera to match the real perspective before modeling.
img2cube is completely free to download and use.
img2cube supports Blender 4.2 LTS and newer. Version 1.0.6 runs entirely inside Blender with no external application, relying only on numpy and mathutils, both of which ship with Blender itself. That means there are no bundled wheels or extra dependencies to install. You work from the Image Editor's N-panel, loading a photo, drawing lines, and solving the camera without leaving the program. If you are on an older Blender release, check the developer's GitHub page for details before installing.
img2cube can be installed directly through Blender's extension system. Open Edit then Preferences then Get Extensions, search for img2cube, and click Install. If you prefer a manual route, download the .zip from the developer's releases and either drag it into Blender or use Get Extensions then Install from Disk. Once installed, load an image in the Image Editor, open the N-panel, and switch to the img2cube tab to begin. The extension is small in size, so installation is quick.
img2cube needs at least two lines per axis across at least two axes, so four lines minimum, drawn along edges that are parallel in real life. You assign each line to the X, Y, or Z axis, then click Solve to recover focal length and rotation. The developer notes that fewer accurate lines beat many rough ones, and that extra lines are mainly useful as snap-point targets. A residual is reported in pixels so you can judge how well the solve fits.
img2cube runs completely inside Blender, with no external application to switch to. It uses only numpy and mathutils, both shipped with Blender, so there are no bundled wheels or additional dependencies to manage. This also makes the extension straightforward to review on the official Blender Extensions store. The full workflow, from loading a photo to placing 3D snap points, happens in the Image Editor and 3D View without leaving Blender.
img2cube is listed as free here, and the developer states it is free and always will be. It is distributed under the GNU General Public License v3.0 or later, which is required for Blender extensions. For current licensing terms or ways to support the project, check the developer's page. The extension is available through Blender's Get Extensions browser as well as the developer's GitHub releases.
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