From 913b72b3176dfd4a613f9fb9de1c985fb13b8ad8 Mon Sep 17 00:00:00 2001
From: Théo de la Hogue
Date: Tue, 19 Sep 2023 13:49:02 +0200
Subject: Working on aruco markers pipeline.

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 .../optic_parameters_calibration.md                | 133 +++++++++++++++++++++
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 create mode 100644 docs/user_guide/aruco_markers_pipeline/advanced_topics/optic_parameters_calibration.md

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diff --git a/docs/user_guide/aruco_markers_pipeline/advanced_topics/optic_parameters_calibration.md b/docs/user_guide/aruco_markers_pipeline/advanced_topics/optic_parameters_calibration.md
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+Calibrate optic parameters
+==========================
+
+A camera device have to be calibrated to compensate its optical distorsion.
+
+![Optic parameters calibration](../../img/optic_calibration.png)
+
+## Print calibration board
+
+The first step to calibrate a camera is to create an [ArUcoBoard](../../argaze.md/#argaze.ArUcoMarkers.ArUcoBoard) like in the code below:
+
+``` python
+from argaze.ArUcoMarkers import ArUcoMarkersDictionary, ArUcoBoard
+
+# Create ArUco dictionary
+aruco_dictionary = ArUcoMarkersDictionary.ArUcoMarkersDictionary('DICT_APRILTAG_16h5')
+
+# Create an ArUco board of 7 columns and 5 rows with 5 cm squares with 3cm ArUco markers inside
+aruco_board = ArUcoBoard.ArUcoBoard(7, 5, 5, 3, aruco_dictionary)
+
+# Export ArUco board with 300 dpi resolution
+aruco_board.save('./calibration_board.png', 300)
+```
+
+!!! note
+      There is **A3_DICT_APRILTAG_16h5_3cm_35cmx25cm.pdf** file located in *./src/argaze/ArUcoMarkers/utils/* folder ready to be printed on A3 paper sheet.
+
+Let's print the calibration board before to go further.
+
+## Capture board pictures 
+
+Then, the calibration process needs to make many different captures of an [ArUcoBoard](../../argaze.md/#argaze.ArUcoMarkers.ArUcoBoard) through the camera and then, pass them to an [ArUcoDetector](../../argaze.md/#argaze.ArUcoMarkers.ArUcoDetector.ArUcoDetector) instance to detect board corners and store them as calibration data into an [ArUcoOpticCalibrator](../../argaze.md/#argaze.ArUcoMarkers.ArUcoOpticCalibrator) for final calibration process.
+
+![Calibration step](../../img/optic_calibration_step.png)
+
+The sample of code below illustrates how to:
+
+* load all required ArGaze objects,
+* detect board corners into a Full HD camera video stream, 
+* store detected corners as calibration data then, 
+* once enough captures are made, process them to find optic parameters and, 
+* finally, save optic parameters into a JSON file.
+
+``` python
+from argaze.ArUcoMarkers import ArUcoMarkersDictionary, ArUcoOpticCalibrator, ArUcoBoard, ArUcoDetector
+
+# Create ArUco dictionary
+aruco_dictionary = ArUcoMarkersDictionary.ArUcoMarkersDictionary('DICT_APRILTAG_16h5')
+
+# Create ArUco optic calibrator
+aruco_optic_calibrator = ArUcoOpticCalibrator.ArUcoOpticCalibrator()
+
+# Create ArUco board of 7 columns and 5 rows with 5 cm squares with 3cm aruco markers inside
+# Note: This board is the one expected during further board tracking
+expected_aruco_board = ArUcoBoard.ArUcoBoard(7, 5, 5, 3, aruco_dictionary)
+
+# Create ArUco detector
+aruco_detector = ArUcoDetector.ArUcoDetector(dictionary=aruco_dictionary, marker_size=3)
+
+# Assuming that live Full HD (1920x1080) video stream is enabled
+...
+
+# Assuming there is a way to escape the while loop
+...
+
+    while video_stream.is_alive():
+
+        # Capture image from video stream
+        image = video_stream.read()
+
+        # Detect all board corners in image
+        aruco_detector.detect_board(image, expected_aruco_board, expected_aruco_board.markers_number)
+
+        # If all board corners are detected
+        if aruco_detector.board_corners_number == expected_aruco_board.corners_number:
+
+            # Draw board corners to show that board tracking succeeded
+            aruco_detector.draw_board(image)
+
+            # Append tracked board data for further calibration processing 
+            aruco_optic_calibrator.store_calibration_data(aruco_detector.board_corners, aruco_detector.board_corners_identifier)
+
+# Start optic calibration processing for Full HD image resolution
+print('Calibrating optic...')
+optic_parameters = aruco_optic_calibrator.calibrate(aruco_board, dimensions=(1920, 1080))
+
+if optic_parameters:
+
+    # Export optic parameters
+    optic_parameters.to_json('./optic_parameters.json')
+
+    print('Calibration succeeded: optic_parameters.json file exported.')
+
+else:
+
+    print('Calibration failed.')
+```
+
+Below, an optic_parameters JSON file example:
+
+```json
+{
+    "rms": 0.6688921504088245,
+    "dimensions": [
+        1920,
+        1080
+    ],
+    "K": [
+        [
+            1135.6524381415752,
+            0.0,
+            956.0685325355497
+        ],
+        [
+            0.0,
+            1135.9272506869524,
+            560.059099810324
+        ],
+        [
+            0.0,
+            0.0,
+            1.0
+        ]
+    ],
+    "D": [
+        0.01655492265003404,
+        0.1985524264972037,
+        0.002129965902489484,
+        -0.0019528582922179365,
+        -0.5792910353639452
+    ]
+}
+```
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