vault backup: 2023-03-16 13:39:33

content/notes/06-homographies.md

@@ -36,4 +36,36 @@ homography for rotating camera
 ![|300](https://i.imgur.com/L6MqmUD.png)
 
 
-> [!INFO] K matric describe parameters of camera. R matric describes rotation of camera. T is zero because the camera is only rotating. H is the homograhy matrix
+> [!INFO] K matric describe parameters of camera. R matric describes rotation of camera. T is zero because the camera is only rotating. H is the homograhy matrix
+
+
+not homographies
+- If we have both: 
+	- Non-planar scene, and 
+	- Translating camera 
+- There is no homography between the images 
+	- Lines may not be preserved 
+	- Cannot make a mosaic 
+	- But we can do stereo
+
+![|150](https://i.imgur.com/8P81y7T.png)
+
+making mosiac
+- To make a mosaic image: 
+	- Need to warp images to align 
+	- This warping is a homography 
+- How to find the homography? 
+	- If a feature at in one image matches to in the other, then
+
+![|300](https://i.imgur.com/lryK0b8.png)
+
+HOMOGRAPHY ESTIMATION IN OPENCV 
+- https://docs.opencv.org/4.4.0/d9/d0c/group__calib3d.html#ga4abc2ece9fab9398f2e560d53c8c9780
+- pts1 – Points in first image (std::vector) 
+- pts2 – Points in second image (std::vector) 
+
+- cv::RANSAC - method to use (we’ll just use RANSAC) 
+- 3.0 – RANSAC threshold 
+
+cv::Mat H = cv::findHomography(pts1, pts2, cv::RANSAC, 3.0);
+