Wiki source code of World Coordinate System

Last modified by Richard Kreissig on 2025/01/30 12:18

version	line-number	content
5.1	1	= Motivation =
3.1	2
5.1	3	Attempting to decouple the SCCharts Controller and physics calculations (amongst other things) from fixed pixel coordinates a world coordinate system was introduced. This coordinate system has its origin in the center between the two bottom flipper tips. Standing in front of the flipper the Y-axis points upwards on the playing field and the X-axis points to the right. One unit in the world coordinate system corresponds to 1m.
	4
	5	The main program relies on a (at compile-time present) transformation matrix definition which can be generated and tested with a small standalone tool. Testing requires recompilation of the tool. As there is no depth information available, points in the image that are in the same 2D position of an orthographic parallel view onto the playing field will be in different positions with the generated transformation, so this solution is certainly not exact.
	6
	7	= Calibration =
	8
	9	== Compiling ==
	10
9.1	11	>
5.1	12
8.1	13	{{{make calibrate}}}
5.1	14
8.1	15	This produces a binary file {{code language="none"}}calibrate{{/code}} in the same directory.
5.1	16
	17	== Usage ==
	18
6.1	19	(% class="wrapped" %)
5.1	20	\|=(((
	21	Button
	22	)))\|=(((
	23	Function
	24	)))
	25	\|(((
	26	1-4
	27	)))\|(((
	28	Choose the index of the point to set
	29	)))
	30	\|(((
	31	t
	32	)))\|(((
	33	Enters a test mode, which prints clicked pixel coordinates in the world coordinate system via the configured transformation matrix in the console. This matrix must be present in the file
	34
	35	{{code language="none"}}
	36	calibration_config.h
	37	{{/code}}
	38
	39	at compile time.
	40	)))
	41	\|(((
	42	w
	43	)))\|(((
	44	Generates and writes a transformation matrix from the four points (if all are present) into the file
	45
	46	{{code language="none"}}
	47	calibration_config.h
	48	{{/code}}
	49
	50
	51	)))
	52	\|(((
	53	q
	54	)))\|(((
	55	Quits the program
	56	)))
	57
3.1	58	= Reference Points =
	59
4.1	60	(% class="wrapped" %)
3.1	61	\|=(% colspan="1" %)(% colspan="1" %)
	62	(((
	63	Point #
	64	)))\|=(((
	65	Point in Image
	66	)))\|=(((
4.1	67	Description (when looking at flipper)
3.1	68	)))\|=(((
	69	Position in World Coordinates (Measured in meters)
	70	)))
	71	\|(% colspan="1" %)(% colspan="1" %)
	72	(((
	73	1
	74	)))\|(((
	75	top right
	76	)))\|(((
4.1	77	Top of the left outlane detector wire
3.1	78	)))\|(((
	79	-0.203, 0.106
	80	)))
	81	\|(% colspan="1" %)(% colspan="1" %)
	82	(((
	83	2
	84	)))\|(((
	85	bottom right
	86	)))\|(((
4.1	87	Horizontal middle of the top edge of the black square on the tube shaped graphic
3.1	88	)))\|(((
	89	-0.164, 0.685
	90	)))
	91	\|(% colspan="1" %)(% colspan="1" %)
	92	(((
	93	3
	94	)))\|(((
	95	bottom left
	96	)))\|(((
4.1	97	Bottom right corner of the letter 'E' trigger (right side of the ramp)
3.1	98	)))\|(((
	99	0.199, 0.637
	100	)))
	101	\|(% colspan="1" %)(% colspan="1" %)
	102	(((
	103	4
	104	)))\|(((
	105	top left
	106	)))\|(((
4.1	107	Bottom of the right outlane detector wire
3.1	108	)))\|(((
	109	0.200, 0.103
	110	)))
	111
	112	[[image:attach:CalibrationPoints.png]]
	113
9.1	114	Uncropped Image
3.1	115	[[image:attach:2020-03-03-181059_1920x1200_scrot.png]]
6.1	116
9.1	117
6.1	118	[[image:attach:geogebra.png]]
	119
9.1	120	Geogebra File
6.1	121
9.1	122	[[geogebra.png>>attach:geogebra.png]]
6.1	123
7.1	124
	125	The reference points used in the calibration (see table) were empirically corrected to the left, as the coordinate system resulting from the generated transformation was slightly shifted to the right. This may have been the case because it is hard to //exactly// match the reference points to pixels in the image. Subsequent calibrations may yield different errors in the coordinate system.

Wiki source code of World Coordinate System

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