Lense Shift
Table of contents
Canvas subdivision for non parallel projections
Take a canvas with the following properties: WxH with a fov defined as F
Example: 960x540 (16/9) @ 70 FoV
Subdivision by half
To calculate the required lense shift values to render two smaller canvases (side-by-side) with a [W/2 x H] = [w x h] size, given it’s relation to canvas height, only the ratio between the w & h of the sub-canvas is required to be calulated
x = +/- 1/2 * w/h
No FoV change required.
This gives us the following two lense shift combinations:
Examples at 480x540 @ 70 FoV
| [-0.5w/h,0] | [0.5w/h,0] |
|---|---|
 |  |
E.G. For the provided subdivisions the offsets would be [+-0.444444444,0].
Subdivision by quarters
To calculate the required lense shift values to render four smaller canvases with a [W/2 x H/2] = [w x h] size with a F/2 = f FoV, given it’s relation to canvas height, only the ratio between the w & h of the sub-canvas is required to be calulated:
x = +/- 1/2 * w/h
&
y = +/- 1/2
This gives us the following lense shift combinations:
Examples at 480x270 @ 35 FoV
| [-0.5w/h,+1/2] | [0.5w/h,+1/2] |
|---|---|
 |  |
| [-0.5w/h,-1/2] | [0.5w/h,-1/2] |
 |  |
E.G. For the provided subdivisions the offsets would be [+-0.888888889, +-0.5].
Ninth part subdivision
To calculate the required lense shift values to render nine smaller canvases with a [W/3 x H/3] = [w x h] size with a F/3? = f FoV, given it’s relation to canvas height, only the ratio between the w & h of the sub-canvas is required to be calulated:
WIP
Sixteenth part subdivision
To calculate the required lense shift values to render sixteen smaller canvases with a [W/4 x H/4] = [w x h] size with a F/4? = f FoV, given it’s relation to canvas height, only the ratio between the w & h of the sub-canvas is required to be calulated:
WIP