From 1a639253c0aa4d82777fa3db5968635c530ebcd8 Mon Sep 17 00:00:00 2001 From: Jet Hughes Date: Thu, 30 Mar 2023 13:34:09 +1300 Subject: [PATCH] vault backup: 2023-03-30 13:34:09 --- content/notes/10-3d-Cameras.md | 35 +++++++++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) diff --git a/content/notes/10-3d-Cameras.md b/content/notes/10-3d-Cameras.md index ca22325bd..0062c95dc 100644 --- a/content/notes/10-3d-Cameras.md +++ b/content/notes/10-3d-Cameras.md @@ -37,4 +37,37 @@ PERSPECTIVE PROJECTION - The pinhole camera - A simple, but useful, model - There is a central point of projection (the pinhole, often a lens in reality) - - Light travels from the world, through the pinhole, to the image plane \ No newline at end of file + - Light travels from the world, through the pinhole, to the image plane +> [!INFO] need a hole that is big enough to get enough light +> but small enough to create a sharp image +> light goes through the hole to the image plane +> pin hole is also the "lens" + +THE PINHOLE CAMERA MODEL +![pin hole top view|300](https://i.imgur.com/bTSLvWR.png) +![pin hole diagam|300](https://i.imgur.com/TfclYHD.png) +> [!INFO] use negative of f as it is behind the pinhole +> find U using similar triangles rule + +![|300](https://i.imgur.com/paeALF6.png) +> [!INFO] now we can project a point from 3d to 2d +> z is multiplies by 1 in the matrix so that the 3rd point of the homogenous coord becomes the z value + +- We can put the image plane in front of the pinhole + - Removes the sign change + - Not practical for real cameras + - The maths works out just fine +![|200](https://i.imgur.com/hxPFHET.png) +![|100](https://i.imgur.com/KEiY1bf.png) + +> [!INFO] cant really convert from 2d back to 3d without knowing focal length and z coord of every point + +TRANSFORMING CAMERAS + +INTRINSICS AND EXTRINSICS +- Often break this down into +![](https://i.imgur.com/3eENBA4.png) + +- Most simple case: +- : camera calibration or intrinsics +- : camera pose or extrinsics \ No newline at end of file