Add camera_calibration example

ci/script.sh

@@ -73,7 +73,7 @@ fi
 # remove tests and examples that require the latest OpenCV version so that they don't fail due to missing modules
 if [[ "${OPENCV_VERSION:-}" != "4.10.0" ]]; then
 	rm -vf tests/*_only_latest_opencv.rs
-	rm -vf examples/dnn_face_detect.rs examples/text_detection.rs
+	rm -vf examples/dnn_face_detect.rs examples/text_detection.rs examples/camera_calibration.rs
 fi
 
 echo "=== Current directory: $(pwd)"

examples/camera_calibration.rs

@@ -0,0 +1,91 @@
+//! Port of code from the tutorial at: https://docs.opencv.org/4.x/dc/dbb/tutorial_py_calibration.html
+
+use std::error::Error;
+use std::fs;
+
+use opencv::core::{no_array, Point2f, Point3f, Size, TermCriteria, TermCriteria_EPS, TermCriteria_MAX_ITER, Vector};
+use opencv::prelude::*;
+use opencv::{calib3d, highgui, imgcodecs, imgproc};
+
+fn main() -> Result<(), Box<dyn Error>> {
+	// termination criteria
+	let criteria = TermCriteria {
+		typ: TermCriteria_EPS + TermCriteria_MAX_ITER,
+		max_count: 30,
+		epsilon: 0.001,
+	};
+
+	// prepare object points, like (0,0,0), (1,0,0), (2,0,0) ....,(6,5,0)
+	let objp_len = 6 * 7;
+	let objp = Vector::from_iter((0..objp_len).map(|i| Point3f::new((i % 7) as f32, (i / 7) as f32, 0.)));
+
+	let images = fs::read_dir(".")?
+		.into_iter()
+		.flatten()
+		.filter(|entry| entry.path().extension().map_or(false, |ext| ext == "jpg"));
+
+	for image in images {
+		// Arrays to store object points and image points from all the images.
+		let mut objpoints = Vector::<Vector<Point3f>>::new(); // 3d point in real world space
+		let mut imgpoints = Vector::<Vector<Point2f>>::new(); // 2d points in image plane.
+
+		let mut img = imgcodecs::imread_def(image.path().to_string_lossy().as_ref())?;
+		let mut gray = Mat::default();
+		imgproc::cvt_color_def(&img, &mut gray, imgproc::COLOR_BGR2GRAY)?;
+
+		let mut corners = Vector::<Point2f>::default();
+		let ret = calib3d::find_chessboard_corners_def(&gray, Size::new(7, 6), &mut corners)?;
+		if ret {
+			objpoints.push(objp.clone());
+
+			imgproc::corner_sub_pix(&gray, &mut corners, Size::new(11, 11), Size::new(-1, -1), criteria)?;
+
+			// Draw and display the corners
+			calib3d::draw_chessboard_corners(&mut img, Size::new(7, 6), &corners, ret)?;
+			highgui::imshow("Source", &img)?;
+
+			imgpoints.push(corners);
+
+			// Calibration
+			let mut mtx = Mat::default();
+			let mut dist = Mat::default();
+			let mut rvecs = Vector::<Mat>::new();
+			let mut tvecs = Vector::<Mat>::new();
+			calib3d::calibrate_camera_def(
+				&objpoints,
+				&imgpoints,
+				gray.size()?,
+				&mut mtx,
+				&mut dist,
+				&mut rvecs,
+				&mut tvecs,
+			)?;
+
+			// Using cv.undistort()
+			let mut dst_undistort = Mat::default();
+			calib3d::undistort_def(&img, &mut dst_undistort, &mtx, &dist)?;
+			highgui::imshow("Result using undistort", &dst_undistort)?;
+
+			// Using remapping
+			let mut mapx = Mat::default();
+			let mut mapy = Mat::default();
+			calib3d::init_undistort_rectify_map(
+				&mtx,
+				&dist,
+				&no_array(),
+				&no_array(),
+				img.size()?,
+				f32::opencv_type(),
+				&mut mapx,
+				&mut mapy,
+			)?;
+			let mut dst_remap = Mat::default();
+			imgproc::remap_def(&img, &mut dst_remap, &mapx, &mapy, imgproc::INTER_LINEAR)?;
+			highgui::imshow("Result using remap", &dst_undistort)?;
+
+			highgui::wait_key_def()?;
+		}
+	}
+	highgui::destroy_all_windows()?;
+	Ok(())
+}