Robobot camera - Revision history

Jca at 11:48, 3 March 2025

2025-03-03T11:48:06Z

← Older revision		Revision as of 13:48, 3 March 2025
Line 1:		Line 1:
	Back to [[Robobot]]		Back to [[Robobot]]

	'''Valid for the 2024 version of Robobot ~~only~~'''		'''Valid for the 2024 version of Robobot'''

	== camera settings ==		== camera settings ==

Jca at 11:47, 3 March 2025

2025-03-03T11:47:43Z

← Older revision		Revision as of 13:47, 3 March 2025
Line 1:		Line 1:
	Back to [[Robobot]]		Back to [[Robobot]]

			'''Valid for the 2024 version of Robobot only'''

	== camera settings ==		== camera settings ==

Jca: /* Use from OpenCV (C++) */

2022-12-06T11:55:15Z

Use from OpenCV (C++)

← Older revision		Revision as of 13:55, 6 December 2022
Line 44:		Line 44:
	cap.set(cv::CAP_PROP_FPS, 25);		cap.set(cv::CAP_PROP_FPS, 25);
	// now the camera is ready for frame capture.		// now the camera is ready for frame capture.
			//
	// debug print of accepted format:		// debug print of accepted format:
	union FourChar		union FourChar

Jca: /* Use from OpenCV (C++) */

2022-12-06T11:52:56Z

Use from OpenCV (C++)

← Older revision		Revision as of 13:52, 6 December 2022
Line 18:		Line 18:
	=== Use from OpenCV (C++) ===		=== Use from OpenCV (C++) ===

	First open and set camera format:		First, open and set the camera format:

	cv::VideoCapture cap;		cv::VideoCapture cap;

	void setup()		void setup()
	{		{

Jca: /* Data formats */

2022-12-06T11:52:14Z

Data formats

← Older revision		Revision as of 13:52, 6 December 2022
Line 12:		Line 12:
	* MJPG coded 1280 x 720 pixels at 25 or 30 FPS		* MJPG coded 1280 x 720 pixels at 25 or 30 FPS
	* MJPG coded 1920 x 1080 pixels at 25 or 30 FPS		* MJPG coded 1920 x 1080 pixels at 25 or 30 FPS
	* MJPG coded 640 x 480 pixels at 25 or 30 FPS; this mode cuts parts of the image to fit the format		* MJPG coded 640 x 480 pixels at 25 or 30 FPS; this mode cuts parts of the image width to fit the format

	It also supports "raw" format as YUYV 4:2:2, but it seems like data loss occurs (fragmented images), so do not use this format.		It also supports "raw" format as YUYV 4:2:2, but it seems like data loss occurs (fragmented images), so do not use this format.

Jca: /* Data formats */

2022-12-06T11:51:52Z

Data formats

← Older revision		Revision as of 13:51, 6 December 2022
Line 12:		Line 12:
	* MJPG coded 1280 x 720 pixels at 25 or 30 FPS		* MJPG coded 1280 x 720 pixels at 25 or 30 FPS
	* MJPG coded 1920 x 1080 pixels at 25 or 30 FPS		* MJPG coded 1920 x 1080 pixels at 25 or 30 FPS
	* MJPG coded 640 x 480 pixels at 25 or 30 FPS, cuts parts of the image to fit the format		* MJPG coded 640 x 480 pixels at 25 or 30 FPS; this mode cuts parts of the image to fit the format

	It also supports "raw" format as YUYV 4:2:2, but it seems like data loss occurs (fragmented images), so do not use this format.		It also supports "raw" format as YUYV 4:2:2, but it seems like data loss occurs (fragmented images), so do not use this format.

Jca: /* Finding 3D position of a known object */

2022-12-06T11:48:10Z

Finding 3D position of a known object

← Older revision		Revision as of 13:48, 6 December 2022
Line 93:		Line 93:
	f D		f D
	The unit of S and D could be in meters.		The unit of S and D could be in meters.

			This can be used to find the 3D position of a known object.

	The distance along the camera axis is thus (when the size of the object is known):		The distance along the camera axis is thus (when the size of the object is known):

Jca: /* Camera calibration */

2022-12-06T11:46:03Z

Camera calibration

← Older revision		Revision as of 13:46, 6 December 2022
Line 84:		Line 84:

	The focal length f is approximately 1008 pixels, when the image format is 1280 x 720.		The focal length f is approximately 1008 pixels, when the image format is 1280 x 720.

			=== Finding 3D position of a known object ===

	The relation between an object with pixel size '''Px''' and the focal length '''f''' is the same as the actual object size '''S''' and the distance '''D''' from the camera to the object along the centre axis of the camera, i.e.		The relation between an object with pixel size '''Px''' and the focal length '''f''' is the same as the actual object size '''S''' and the distance '''D''' from the camera to the object along the centre axis of the camera, i.e.

Jca: /* Camera calibration */

2022-12-06T11:44:37Z

Camera calibration

← Older revision		Revision as of 13:44, 6 December 2022
Line 81:		Line 81:

	But, close to the centre of the image, this may not be needed.		But, close to the centre of the image, this may not be needed.
	The main parameter here is the focal-length.		The main parameter here is the focal length.

	The focal length f is approximately 1008 pixels, when the image format is 1280 x 720.		The focal length f is approximately 1008 pixels, when the image format is 1280 x 720.

	The relation between an object with pixel size '''Px''' and the focal-length '''f''' is the same as the ~~real~~ object size '''S''' and the distance '''D''' from the camera to the object along the centre axis of the camera, i.e.		The relation between an object with pixel size '''Px''' and the focal length '''f''' is the same as the actual object size '''S''' and the distance '''D''' from the camera to the object along the centre axis of the camera, i.e.

	Px S		Px S
	--- = ---		--- = ---
	f D		f D
	The unit of S and D could me in meters.		The unit of S and D could be in meters.

			The distance along the camera axis is thus (when the size of the object is known):
			* D = S * f / Px

			The 3D position of the object can then be found in camera coordinates as (with x being to the right and y directed down

			* xm = (xi - xc) * D / f
			* ym = (yi - yc) * D / f

			where xm and ym are distances in meters from the camera axis, xi and yi is the image column and row for the (centre of the object), xc and yc are the column and row for the centre of the image, D is the distance to the object in meters and f is the focal length in pixels.

Jca: /* Camera calibration */

2022-12-06T11:33:54Z

Camera calibration

← Older revision		Revision as of 13:33, 6 December 2022
Line 85:		Line 85:
	The focal length f is approximately 1008 pixels, when the image format is 1280 x 720.		The focal length f is approximately 1008 pixels, when the image format is 1280 x 720.

	The relation between an object with pixel size Px and the focal-length f is the same as the real object size S and the distance D from the camera to the object along the centre axis of the camera, i.e.		The relation between an object with pixel size '''Px''' and the focal-length '''f''' is the same as the real object size '''S''' and the distance '''D''' from the camera to the object along the centre axis of the camera, i.e.

	Px S		Px S