# Is there a detailed derivation process for 3D circular geometric projection?

**URL:** https://discourse.itk.org/t/is-there-a-detailed-derivation-process-for-3d-circular-geometric-projection/6121
**Category:** Uncategorized
**Created:** [August 1, 2023, 6:51am UTC](https://discourse.itk.org/t/is-there-a-detailed-derivation-process-for-3d-circular-geometric-projection/6121 "2023-08-01T06:51:38Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![ma1282029525](https://discourse.itk.org/user_avatar/discourse.itk.org/ma1282029525/32/3084_2.png) [@ma1282029525](https://discourse.itk.org/u/ma1282029525)
#### Post date: [August 1, 2023, 6:51am UTC](https://discourse.itk.org/t/is-there-a-detailed-derivation-process-for-3d-circular-geometric-projection/6121/1 "2023-08-01T06:51:38Z")

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![image](https://discourse.itk.org/uploads/default/original/2X/6/631a653e8f5cc08e59521a09a465576b504f7771.png)  
I didn’t quite understand this part

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### Author: ![simon.rit](https://discourse.itk.org/letter_avatar_proxy/v4/letter/s/f08c70/32.png) [@simon.rit](https://discourse.itk.org/u/simon.rit)
#### Post date: [August 1, 2023, 8:01pm UTC](https://discourse.itk.org/t/is-there-a-detailed-derivation-process-for-3d-circular-geometric-projection/6121/2 "2023-08-01T20:01:28Z")

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Not more than that. The matrices are in homogeneous coordinates. MR is a rotation matrix. The two matrices with offsets are translation matrices. The matrix with diagonal elements is a projection matrix which is essentially the application of the Thales theorem.