Comparing Orthographic and Perspective Cameras

I feel this is sort of a amateur question to ask so sorry and I haven’t found really found anything helpful. I was just wondering when I would want to use either a Orthographic or Perspective camera?. I use a orthographic camera all the time and it seems to work fine. When i switch to using a perspective camera, nothing seems to really change.

So I was wondering if someone could tell me the reason for choosing one over the other?

A perspective camera is how we see the real world. If we take a look at the things around us, they have depth and we can judge their distance. Imagine looking at a very long road. It will appear to get narrower as it goes further into the distance. This is due to perspective.

An orthographic camera however removes this sense of perspective. Objects are drawn without perspective distortion.

See the image below:
74544-temp.png

See how in the perspective render the cubes appear to be moving further away, have depth, and resemble how we would see them in the real world. In orthographic the edges of the cube remain parallel.

As a rough guide you would use the following cameras for the following situations:

Perspective:

  • Need to simulate a real world view
  • Scene needs to have depth
  • Commonly used in 3D games

Orthograhpic

  • Objects don’t need to have depth
  • Objects are flat
  • Commonly used in 2D games

You mentioned you use an Orthographic Camera all the time. Do you make a lot of 2D games? If so you won’t notice a change unless your objects are 3D. Try adding a cube to your scene and changing the camera mode between Orthographic and Perspective. You should notice a difference.

Isometric games use an Orthographic camera. In the image below, see how all the cubes appear to be the same size? This is due to Orthographic rendering.
74545-temp.jpg