How can calculate perspective camera parameters from orthographic camera parameters (left, right, top, bottom, near, far)?

Specifically I don't know how calculate the FOV for a perspective camera from orthographic camera.

  • 2
    \$\begingroup\$ You should create a question (or edit this one) that describes the feature that you need instead of asking about solution implementation. (XY problem) This way we could give you better answers. \$\endgroup\$
    – Vaillancourt
    Jun 17, 2016 at 15:19
  • \$\begingroup\$ In theory, if your perspective FOV will be infinitely small, then said perspective matrix will kind of resemble orthographic matrix .. but I'm sure you need something less "extreme". \$\endgroup\$
    – Kromster
    Jun 17, 2016 at 15:34
  • \$\begingroup\$ I need way to get data for creation perspective camera (fov ,aspect,near,far , matrix) if I have data for creation orthographic camera (left, right, top, bottom, near, far, matrix). \$\endgroup\$ Jun 17, 2016 at 15:46
  • \$\begingroup\$ What are these matrices? The way to project stuff on screen is by using lots of matrices, so just saying 'matrix' adds some confusion... \$\endgroup\$
    – Vaillancourt
    Jun 17, 2016 at 16:17
  • \$\begingroup\$ Matrix determine position of camera and direction of camera view. \$\endgroup\$ Jun 17, 2016 at 16:25

1 Answer 1


You can't.

The two matrices are constructed in completely different ways.

There are tons of ways to find more information on that by googling.

You can't get the field of view from the orthographic camera because there is no such thing.

  • \$\begingroup\$ Isn't there a hackish way to get the fov? Like 0.5f * (right - left) / (far - near) which would give us 0.5f * tan(fov) (which we can use to make perspective matrix given a ratio)? Though the view will be completely different from the ortho one ofc.. \$\endgroup\$
    – Greffin28
    Jun 17, 2016 at 15:32
  • \$\begingroup\$ One could hackishly try to approximate the volume rendered; not sure about how I'd go about it exaclty, but you're right, the views would look different. \$\endgroup\$
    – Vaillancourt
    Jun 17, 2016 at 15:41

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