# How can I set a custom projection matrix for rendering?

How can I set a camera projection matrix? I want to render a perspective like the old SimCity 1989:

• – gandalf3 Feb 6 '14 at 17:13
• Great! Thanks very much! Please tell me how yu find the angles (curious how find them). – Châu Feb 8 '14 at 8:02
• For my answer below I just eyeballed it based on the image you linked to. – gandalf3 Feb 8 '14 at 8:08
• This not correct, is close but not correct. x and y direction lines not 90°. In blender picture look close, x grid lines almost horizontal but not horizontal, y lines OK. – Châu Feb 11 '14 at 9:05
• – ideasman42 Apr 8 '14 at 20:23

For orthographic rendering Blender can't take a custom projection matrix, however you can shear an orthographic projection to get the desired results.

• Use an orthographic camera, with the camera set at an angle (45 degrees on the X and Z axis).
• In the render settings, set the Aspect X to sqrt(2)
This will give something almost exactly what you're looking for, except that its rotated 45 degrees.
• To correct the rotation, use the compositors Distort -> Transform node.

Notes:

• rotating the image will loose some accuracy, so you'll want to render larger, then scale down.
• in the compositor you can scale down by 1/sqrt(2) to avoid loosing the corners.
• Depth/Mist won't work as you might want, however its probably possible to use a gradient and offset the depth in the compositor.
• Excellent work! Use rotation –45° for SimCity direction. – Châu Apr 11 '14 at 10:07
• Careful, x and y direction ok; but z direction is not correct for mist or depth effects. – Châu May 6 '14 at 10:06
• @Châu good point, noted in answer. – ideasman42 May 6 '14 at 18:52