There is only 7 intervals between 8 measure.

[teyssieuman]

There is only 7 interval between 8 measures.

The difference between the value of start_angle_ and the previous value of end_angle_ is relatively constant and has approximately the same value than the difference between start_angle_ and end_angle_ divided by 7.0.

My hypothesis is that the start and end angle corresponds respectively to the angle of the first and the last angle.

[teyssieuman]

I added another modification. The measured geometry seams far better

[rossihwang]

There is only 7 interval between 8 measures.

The difference between the value of start_angle_ and the previous value of end_angle_ is relatively constant and has approximately the same value than the difference between start_angle_ and end_angle_ divided by 7.0.

My hypothesis is that the start and end angle corresponds respectively to the angle of the first and the last angle.

thanks for your contribution!

indeed, we don't exactly know whether the endangle is with the last range data or behind it. it's hard to tell the little difference in the step angle(with eyes). any ideas to prove it?

on my point of view, if I'm the lidar designer, I would prone to "divided by 8", cause this can be computed fast by bit shift on MCU

[teyssieuman]

I based my observation on data as those ones:

start_angle	length_0	length_1	length_2	length_3	length_4	length_5	length_6	length_7	end_angle	'speed'
355.297	32768	32768	32768	32768	32768	32768	32768	32768	1.67188	1.67188	19981
2.5625	32768	5001	32768	4975	4929	32768	32768	32768	8.8125	8.8125	19980
9.70312	32768	32768	32768	4889	4877	32768	32768	32768	15.9531	15.9531	19980
16.8438	32768	32768	32768	32768	32768	32768	32768	32768	23.0938	23.0938	19980
24.1562	32768	32768	32768	1720	1725	1730	1733	32768	30.4219	30.4219	19980
31.3281	32768	32768	32768	32768	32768	32768	32768	32768	37.5938	37.5938	19980
38.5	32768	32768	1838	32768	32768	32768	32768	32768	44.7656	44.7656	19980
45.6562	32768	32768	32768	32768	32768	32768	32768	32768	52.0312	52.0312	19980
52.9219	32768	32768	282	32768	32768	32768	32768	32768	59.2031	59.2031	19980
60.1094	32768	32768	32768	1483	32768	1521	1530	1552	66.375	66.375	19980
67.2812	1567	1584	2143	1319	1185	1214	32768	1500	73.6875	73.6875	19980
74.5938	1482	1461	1449	1434	1416	1402	32768	32768	80.8906	80.8906	19979
81.7812	32768	32768	32768	32768	32768	32768	32768	32768	88.0781	88.0781	19979
88.9844	32768	321	320	320	321	32768	32768	32768	95.2812	95.2812	19979
96.2031	32768	32768	32768	32768	32768	32768	32768	32768	102.5	102.5	19977
103.391	32768	32768	32768	32768	32768	32768	32768	32768	109.688	109.688	19977
110.578	32768	32768	32768	32768	1651	1652	32768	32768	116.859	116.859	19977
117.766	1663	32768	556	558	561	32768	32768	32768	123.984	123.984	19977
124.875	32768	32768	32768	32768	32768	32768	32768	32768	131.125	131.125	19975
132.031	32768	32768	32768	32768	32768	32768	32768	32768	138.281	138.281	19975
139.172	32768	32768	32768	32768	236	32768	32768	32768	145.125	145.125	19975
146.016	32768	32768	32768	32768	32768	32768	32768	32768	152.172	152.172	19974
153.062	32768	32768	32768	32768	32768	32768	32768	32768	159.234	159.234	19974
160.109	32768	32768	32768	32768	32768	32768	32768	32768	166.281	166.281	19974
167.156	32768	32768	32768	32768	32768	32768	32768	32768	173.641	173.641	19972
174.531	32768	32768	32768	32768	32768	32768	32768	32768	180.75	180.75	19972
181.641	32768	32768	32768	32768	32768	32768	32768	32768	187.859	187.859	19972
188.75	32768	32768	32768	32768	32768	32768	32768	32768	194.875	194.875	19972
195.75	32768	32768	32768	32768	32768	32768	32768	32768	201.938	201.938	19970
202.828	32768	32768	32768	32768	32768	32768	32768	32768	209	209	19970
209.891	32768	32768	32768	32768	32768	32768	32768	32768	216.312	216.312	19970
217.203	32768	32768	32768	32768	32768	32768	32768	32768	223.422	223.422	19968
224.312	32768	32768	32768	32768	32768	32768	32768	32768	230.547	230.547	19968
231.438	32768	32768	168	32768	161	158	155	154	237.656	237.656	19968
238.547	32768	32768	32768	32768	32768	32768	32768	32768	244.969	244.969	19968
245.859	32768	32768	32768	32768	32768	32768	32768	32768	252.125	252.125	19967
253.016	32768	32768	32768	32768	32768	32768	32768	32768	259.266	259.266	19967
260.172	32768	32768	32768	32768	32768	32768	32768	32768	266.516	266.516	19967
267.406	392	32768	32768	32768	1152	1122	1092	1065	273.672	273.672	19965
274.562	1039	1014	993	973	1001	32768	2242	2229	280.828	280.828	19965
281.734	2203	2184	2164	2141	2128	2119	2105	2085	288.031	288.031	19965
288.922	2068	1529	1522	1524	1523	1526	1528	1530	295.188	295.188	19964
296.078	1536	1539	1543	1546	1550	1556	1573	1593	302.344	302.344	19964
303.234	1603	1607	1545	1468	1476	1485	1416	1371	309.484	309.484	19964
310.375	1330	1291	1253	1223	1202	1216	1229	1241	316.75	316.75	19964
317.641	1257	1271	1285	1303	1318	1335	1353	1368	323.906	323.906	19962
324.797	1390	1403	1402	1391	1461	1478	1493	1750	331.062	331.062	19962
331.969	1728	1696	1697	1720	1734	1711	2139	2180	338.047	338.047	19962
338.938	2109	2185	2118	1337	1339	2103	32768	4806	345.141	345.141	19960
346.031	2867	32768	820	786	756	729	702	699	352.234	352.234	19960
353.125	32768	32768	32768	32768	32768	32768	32768	32768	359.328	359.328	19960
0.484375	32768	32768	32768	32768	5043	4998	4954	3260	6.75	6.75	19959

here, I observed that the difference between the end angle of a line and start_angle of the following line is quite constant and is approximately equal to the difference between start-end angle of a same line.

So, since I thing that the difference between two consecutive angle is constant (lets say delta), the observation fits this hypothesis.

start_angle(n) - end_angle(n-1) = delta

end_angle(n) - start_angle(n) = 7 * delta

For the second commit, I'm not sure of myself yet. All I can say for now is that the "laser scan figure" is far less deformed with this configuration.

[Vidicon]

@teyssieuman we chose 400 measurements instead of 360 because of the packages send by the lidar before the angle resets.

https://github.com/Vidicon/camsense-X1/issues/1#issuecomment-658975412

Will look into the "There is only 7 intervals between 8 measure"