Compositing with equirectangular panos : (1)

First, considering the 2/1 equirectangular projection with Tissot’s indicatrix, we can see that the more the apparent vertical angle, the more the deformation :

equirectangular projection
Fabkzo’s equirectangular study


To my point of view 60° vertical angle seems to be the ultimate low deformation limit, so I need to calculate the minimal and maximal distances to my subject, depending on its size.
The secret, in fact, since all the panos I’ve seen so far presents deformed due to the camera’s height is to take the middle of your subject as the horizontal focus point.




We can then use a common formula, also known as the « apparent size formula » , often used in astronomy , link here :
Wikipedia: Angular diameter

So : D = ((d/2)/tanA/2))

« D » as the distance to the subject, « d » the subject’s size.
In other terms: A= 2*arctan(d/2D)
Now considering multiple subjects with different sizes I can master the composition if I want to make a stylized flat equirectangular pano.

One too close subject
Failed, too close, unless you want to play with the deformation.
You can now play with subjects positions in order to see what it does; those are my results, done with Blender :

3 in line looking at the same direction3 inline schema

3 in line facing the camera3-facing the camera

5 inline facing the camera5-inline facing the camera schema

5 facing the camera W5-facing the camera W schema

Hence I think you can now apply portrait art to 360° panophotography.
But remember you’ll face a lot of problemes with lights, focus, focla length, subject’s speed etc … to make something very stylized.

Stay tuned for more results .
#360 #equirectangular #portrait art photography #compositing

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