powergravity
Posts: 32
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High rate camera for Pi 3

Sun Dec 25, 2016 12:47 pm

Hello,

Is there a high rate camera for the Pi3 on the market?
I am looking for a camera which is able to record at least at 100 fps.

Thank you and Merry Christmas,
Pm

powergravity
Posts: 32
Joined: Sun Dec 25, 2016 12:44 pm

Re: High rate camera for Pi 3

Mon Dec 26, 2016 10:41 pm

Anyone?

6by9
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Re: High rate camera for Pi 3

Mon Dec 26, 2016 11:20 pm

The standard 8MP Pi camera should run at 100fps. Easily at vga, but potentially at 720p too.
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powergravity
Posts: 32
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Re: High rate camera for Pi 3

Wed Dec 28, 2016 10:21 am

Hello,

Thank you for your answer.

Every datasheets and topics that I read about the Pi cam notice 90 fps for max recording rate whereas according to the CMOS Sony IMX219 datasheet the HW is able to 120 fps.
Is it a data processing limit?

I am a litlle bit lost....

Thank you in advance,
Pm

6by9
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Re: High rate camera for Pi 3

Wed Dec 28, 2016 5:38 pm

OK, it's not quite so clear cut.

The IMX219 sensor does have a mode which can read out 1280x720 at 120fps.
The image processing pipe on the SoC can run at around 170MPix/s, so should be able to cope with that rate of ~110MPix/s.
The codec block is rated for H264 level 4.0, which maxes out at 68.3fps on 720P frames. It can be overclocked to achieve better than that, but results are not guaranteed - my recollection of experiments when the camera first came out achieved at least 110fps at 720P. Drop to VGA and you could theoretically get 204fps through it, or 130fps at 800x600.
MJPEG may be able to achieve a a higher rate, but it's far less efficient as a codec, and the implementation isn't efficient in the first place.
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donburch
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Re: High rate camera for Pi 3

Thu Dec 29, 2016 11:51 am

I just came across this at kickstarter https://www.kickstarter.com/projects/16 ... escription. object detection at 120fps in a self-contained module (but only 1.3MegaPixel).

6by9
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Re: High rate camera for Pi 3

Thu Dec 29, 2016 2:34 pm

donburch wrote:I just came across this at kickstarter https://www.kickstarter.com/projects/16 ... escription. object detection at 120fps in a self-contained module (but only 1.3MegaPixel).
If that does the job for you then great, but:
(a) it's not available, nor has it achieved the funding level so may never exist.
(b) 120fps is only available at QCIF. Pi camera should be able to do 720P120 (spec of H264 block above is irrelevant as you aren't video encoding). Just testing on a Pi2 and I've got 720P at 107fps via V4L2 without any overclocking. 120fps should be easily within reach with a small overclock, or 960x720 runs happily at 120fps with no overclock using about 6% of the ARM cores (it will be using a large percentage of the VPU part of the VideoCore blocks, but the QPU blocks which also allow extra compute will be nearly idle).
(c) Quad A7 vs Quad A53. A53 is slightly more powerful (2.24DMIPS/MHz) at the same clock than the A7 (1.9DMIPS/MHz) even if you ignore it being a 64bit processor. That was one of the reasons it was chosen in the change from Pi2 to Pi3, even though Raspbian is still sticking with 32bit for now.
(d) You're going to need something else sitting alongside the JeVois to handle the output, so the cost analysis is a little flawed.
(e) boot time comparison is untrue. My Pi2 boots in 12seconds using Raspbian Lite and I'd expect a Pi3 to be similar or better. With further tweaking it is possible to get down to around the 5 second mark that they achieve, but doing so doesn't fit with the Pi being a general purpose computer for educational purposes.

I have noticed that the max framerate you can request from V4L2 is currently 90 so that ought to be tweaked, but otherwise the PiCamera should give better results for not very much more money ($35 Pi3, $25 Pi camera, $4 case + $3 heatsink = $67) and is available.
Horses for courses.
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powergravity
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Re: High rate camera for Pi 3

Fri Dec 30, 2016 6:54 am

Hi,

Thank you for detailed answers.

Some words about my project becomes essential. I am working on a motorcycle data logger to validate my PhD theorical works about active safety systems for powered two wheeled vehicles. I would like to try to estimate roll angle from the video recording. To validate the results I need to compare with IMU data which is record at 100 Hz, that is why I need 100 images each second (it enough for my project i don't need more). To acquire sensor data I am using an Arduino and so the Pi 3 will be only dedicated to record the video.

As said in (a), I am looking for a solution which exists now.

I am interesting in your comment (b) because I have ever a raspicam v2.1 and a Pi 3.

I am novice in video programming (and not familiar with overclocking) so I am looking for the most accessible method to reach my objective. What do you advice me ? Any readings or tutorials ?

Thank you very much,
Pm

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Re: High rate camera for Pi 3

Fri Dec 30, 2016 9:42 am

Going to come at this from out of the box, but why can't you use an accelerator/orientation chip attached to Arduino to do this? Video processing to get the roll angle won't be very easy at all.

THis page has some references http://www.geekmomprojects.com/gyroscop ... on-a-chip/
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powergravity
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Re: High rate camera for Pi 3

Fri Dec 30, 2016 9:51 am

Hi,

Thanks for tour reactivity. I am working in research field (not industrial) so my job is to test every possibility to estimate motorcycle dynamics. That is why I am trying to use a camera ans also an IMU. Moreover more and more vehicles are equipped with camera to "see" the environnement (other road users, road, ...) and why not add other functionality as roll angle estimation.

Have a good day,
Pm

6by9
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Re: High rate camera for Pi 3

Fri Dec 30, 2016 10:51 am

Simpler question - what resolution do you need to record at? That is going to be the limiting factor based on the H264 level required.

960x540 @ 100fps is within level 4.0, so should work out of the box.

Code: Select all

raspivid -w 960 -h 540 -fps 100 -o video.h264 -pts timecodes.txt -t 10000
mkvmerge -o video.mkv --timecodes 0:timecodes.txt video.h264
Should give you a correctly recorded 10 second file with accurate timestamps (ie play back at the correct rate. The raw H264 stream has no frame rate or timestamp information).
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powergravity
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Re: High rate camera for Pi 3

Fri Dec 30, 2016 5:54 pm

The easiest way to answer is to return the question, which resolution can I get at 100 fps with a good accuracy?

Thank you very much for the code I will try it as soon as I will be back at home. Is there a way to check the timing accuracy of the recording ?

I would like start the recording from the Arduino simultaneously with the sensors. To do it I have realized a voltage divider with 2 resistances to convert Arduino 5V logic to 3.3V for the Pi. I don't have any idea if there will be a delay or if I will be able to perfectly synchronized camera with sensors?

Thank you very much for your help,
Pm

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aTao
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Re: High rate camera for Pi 3

Fri Dec 30, 2016 7:47 pm

I think you may be approaching it the wrong way. As I understand you want 100fps because another part of the system runs at that speed. What you sould really focus on is the actual data rate of the signal you are recording, and I think 100fps for roll on a bike is a bit OTT.
So, if you could get a sensible signal at lower fps then it is just a matter of tweening the result of the horizon detection to marry up with the other data.


As for an orientation sensor then it has just got to use the gyro.
>)))'><'(((<

6by9
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Re: High rate camera for Pi 3

Fri Dec 30, 2016 8:58 pm

powergravity wrote:The easiest way to answer is to return the question, which resolution can I get at 100 fps with a good accuracy?
"Accuracy" of what?
powergravity wrote:Thank you very much for the code I will try it as soon as I will be back at home. Is there a way to check the timing accuracy of the recording ?
Have a look at the timecodes.txt file. It contains the timestamp on the GPU side for the frame start being received, so is the end of exposure of the first line. They should be uniformly spaced within a few usecs (interrupt latency is pretty good on the GPU).
powergravity wrote:I would like start the recording from the Arduino simultaneously with the sensors. To do it I have realized a voltage divider with 2 resistances to convert Arduino 5V logic to 3.3V for the Pi. I don't have any idea if there will be a delay or if I will be able to perfectly synchronized camera with sensors?
I think you've missed the fact that this is a rolling shutter sensor (in common with almost all CMOS sensors >1MPix). That means that the lines aren't all being exposed at the same time, so what event would you want to synchronise to? Frame start (end of exposure/start of readout of the first line), Frame End (end of exposure/start of readout of the last line), or somewhere in between?
There is an option in raspivid to trigger off various events, but I don't believe GPIO is currently supported. It only triggers a signal to the GPU to start recording, it doesn't synchronise the low level sensor to the signal.
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aTao
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Re: High rate camera for Pi 3

Fri Dec 30, 2016 10:53 pm

6by9 wrote: I think you've missed the fact that this is a rolling shutter sensor (in common with almost all CMOS sensors >1MPix). That means that the lines aren't all being exposed at the same time, so what event would you want to synchronise to? Frame start (end of exposure/start of readout of the first line), Frame End (end of exposure/start of readout of the last line), or somewhere in between?.
Surely there is a way to calibrate to almost any shutter profile*, especially is there is significant image processing happening.

* both timing and distortion.
>)))'><'(((<

powergravity
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Re: High rate camera for Pi 3

Sat Dec 31, 2016 7:24 am

Hi,
I think you may be approaching it the wrong way. As I understand you want 100fps because another part of the system runs at that speed. What you sould really focus on is the actual data rate of the signal you are recording, and I think 100fps for roll on a bike is a bit OTT.
I have ever performed some tests with another instrumented motorcycle and I don't think it is OTT because motorcycle dynamics is very fast.
Image.
The blue line is the measured roll angle with a SBG IMU and the red line the estimated roll with an observer. Even if data are filtered, it seems not over sampled!

Moreover my job is to focus my work on lateral manoeuvers (turn, overtaking) and not on straight driving that is why I need high fps. To conclude with this remark, as a PhD student I spend lot of time to read papers, papers and papers again and I can provide you lot of references on motorcycle data logger for research (not for common use) where authors use at least 100 Hz for the sensor loops.
"Accuracy" of what?

Maybe my question was a little bit stupid. It means that I was thinking I could have a kind of time drifting.
I think you've missed the fact that this is a rolling shutter sensor (in common with almost all CMOS sensors >1MPix). That means that the lines aren't all being exposed at the same time, so what event would you want to synchronise to? Frame start (end of exposure/start of readout of the first line), Frame End (end of exposure/start of readout of the last line), or somewhere in between?
There is an option in raspivid to trigger off various events, but I don't believe GPIO is currently supported. It only triggers a signal to the GPU to start recording, it doesn't synchronise the low level sensor to the signal.
I am not familiar with camera sensors so I didn’t have any idea that I will have rolling shutter. Is there a way to avoid it? The main data logger code is started from a hardware button. Every loop, I test the Boolean value of the button and if it is true, I start to record all the data. So I would launch the camera recording with the same button.
I have read some topics about external button for raspicam (as viewtopic.php?t=77095&p=550289,...). Why I could not use it in my project?

Thank you very much and enjoy the last day of the year,
Pm

powergravity
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Re: High rate camera for Pi 3

Sat Dec 31, 2016 7:54 am

Re,
Have a look at the timecodes.txt file. It contains the timestamp on the GPU side for the frame start being received, so is the end of exposure of the first line. They should be uniformly spaced within a few usecs (interrupt latency is pretty good on the GPU).
Whit your code:

Code: Select all

raspivid -w 960 -h 540 -fps 100 -o video.h264 -pts timecodes.txt -t 5000
mkvmerge -o video.mkv --timecodes 0:timecodes.txt video.h264
I am performing some tests but I have some problem with timing:
-the recording timer is to fast according to the 10 ms expected :shock:
-it is not able to reach the desired 5 seconds of total recording

Below the txt file:

Code: Select all

# timecode format v2
0.000
9.970
19.941
29.912
39.883
49.853
59.824
69.795
79.766
89.736
99.707
109.678
119.648
129.620
139.592
149.562
159.531
169.503
179.474
189.445
199.418
209.384
219.356
229.327
239.296
249.267
259.237
269.208
279.179
289.150
299.120
309.091
319.062
329.032
339.002
348.975
358.944
368.915
378.886
388.856
398.827
408.798
418.768
428.739
438.710
448.680
458.651
468.621
478.592
488.563
498.534
508.504
518.475
528.446
538.416
548.387
558.358
568.328
578.299
588.270
598.240
608.211
618.182
628.153
638.123
648.097
658.065
668.037
678.009
687.996
697.950
707.918
717.891
727.860
737.831
747.801
757.772
767.743
777.713
787.683
797.655
807.625
817.595
827.566
837.537
847.507
857.478
867.449
877.420
887.391
897.361
907.331
917.302
927.273
937.243
947.215
957.185
967.155
977.127
987.098
997.069
1007.040
1017.010
1026.981
1036.951
1046.922
1056.892
1066.865
1076.834
1086.804
1096.779
1106.751
1116.720
1126.690
1136.660
1146.631
1156.602
1166.572
1176.541
1186.515
1196.485
1206.455
1216.426
1226.394
1236.367
1246.338
1256.310
1266.279
1276.250
1286.219
1296.190
1306.160
1316.130
1326.101
1336.072
1346.042
1356.013
1365.985
1375.954
1385.925
1395.897
1405.867
1415.838
1425.808
1435.780
1445.749
1455.721
1465.691
1475.661
1485.632
1495.602
1505.573
1515.544
1525.514
1535.485
1545.456
1555.428
1565.398
1575.368
1585.338
1595.309
1605.280
1615.250
1625.222
1635.197
1645.165
1655.136
1665.106
1675.074
1685.048
1695.020
1704.990
1714.961
1724.929
1734.901
1744.872
1754.843
1764.813
1774.781
1784.753
1794.724
1804.694
1814.666
1824.636
1834.607
1844.578
1854.548
1864.518
1874.489
1884.459
1894.430
1904.400
1914.371
1924.343
1934.312
1944.283
1954.254
1964.225
1974.195
1984.166
1994.139
2004.108
2014.079
2024.048
2034.019
2043.990
2053.961
2063.931
2073.902
2083.873
2093.843
2103.814
2113.785
2123.755
2133.726
2143.697
2153.670
2163.641
2173.613
2183.582
2193.553
2203.524
2213.494
2223.465
2233.435
2243.406
2253.376
2263.348
2273.318
2283.288
2293.259
2303.230
2313.200
2323.172
2333.140
2343.110
2353.083
2363.052
2373.022
2382.993
2392.963
2402.935
2412.905
2422.877
2432.846
2442.817
2452.789
2462.761
2472.729
2482.700
2492.670
2502.641
2512.612
2522.583
...
4516.719
4526.690
4536.660
4546.634
4556.602
4566.572
4576.543
4586.513
4596.484
4606.455
4616.425
4626.396
4636.367
Do you have any idea about the source of the issue ?

Thank you very much,
Pm

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aTao
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Re: High rate camera for Pi 3

Sat Dec 31, 2016 8:02 am

powergravity wrote:Hi,
I think you may be approaching it the wrong way. As I understand you want 100fps because another part of the system runs at that speed. What you sould really focus on is the actual data rate of the signal you are recording, and I think 100fps for roll on a bike is a bit OTT.
I have ever performed some tests with another instrumented motorcycle and I don't think it is OTT because motorcycle dynamics is very fast.
Image.
The blue line is the measured roll angle with a SBG IMU and the red line the estimated roll with an observer. Even if data are filtered, it seems not over sampled!

Moreover my job is to focus my work on lateral manoeuvers (turn, overtaking) and not on straight driving that is why I need high fps. To conclude with this remark, as a PhD student I spend lot of time to read papers, papers and papers again and I can provide you lot of references on motorcycle data logger for research (not for common use) where authors use at least 100 Hz for the sensor loops.
OK, so, just as a reference, your image is 1150 pixels wide. `That gives a horizontal (time) resolution of about 8 pixels per second, equivalent to 8fps.
>)))'><'(((<

6by9
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Re: High rate camera for Pi 3

Sat Dec 31, 2016 9:38 am

powergravity wrote:Whit your code:

Code: Select all

raspivid -w 960 -h 540 -fps 100 -o video.h264 -pts timecodes.txt -t 5000
mkvmerge -o video.mkv --timecodes 0:timecodes.txt video.h264
I am performing some tests but I have some problem with timing:
-the recording timer is to fast according to the 10 ms expected :shock:
-it is not able to reach the desired 5 seconds of total recording

Below the txt file:

Code: Select all

# timecode format v2
0.000
9.970
19.941
29.912
39.883
49.853
59.824
69.795
79.766
89.736
99.707
109.678
119.648
129.620
139.592
149.562
159.531
169.503
179.474
189.445
199.418
209.384
219.356
229.327
239.296
249.267
259.237
269.208
279.179
289.150
299.120
309.091
319.062
329.032
339.002
348.975
358.944
368.915
378.886
388.856
398.827
408.798
418.768
428.739
438.710
448.680
458.651
468.621
478.592
488.563
498.534
508.504
518.475
528.446
538.416
548.387
558.358
568.328
578.299
588.270
598.240
608.211
618.182
628.153
638.123
648.097
658.065
668.037
678.009
687.996
697.950
707.918
717.891
727.860
737.831
747.801
757.772
767.743
777.713
787.683
797.655
807.625
817.595
827.566
837.537
847.507
857.478
867.449
877.420
887.391
897.361
907.331
917.302
927.273
937.243
947.215
957.185
967.155
977.127
987.098
997.069
1007.040
1017.010
1026.981
1036.951
1046.922
1056.892
1066.865
1076.834
1086.804
1096.779
1106.751
1116.720
1126.690
1136.660
1146.631
1156.602
1166.572
1176.541
1186.515
1196.485
1206.455
1216.426
1226.394
1236.367
1246.338
1256.310
1266.279
1276.250
1286.219
1296.190
1306.160
1316.130
1326.101
1336.072
1346.042
1356.013
1365.985
1375.954
1385.925
1395.897
1405.867
1415.838
1425.808
1435.780
1445.749
1455.721
1465.691
1475.661
1485.632
1495.602
1505.573
1515.544
1525.514
1535.485
1545.456
1555.428
1565.398
1575.368
1585.338
1595.309
1605.280
1615.250
1625.222
1635.197
1645.165
1655.136
1665.106
1675.074
1685.048
1695.020
1704.990
1714.961
1724.929
1734.901
1744.872
1754.843
1764.813
1774.781
1784.753
1794.724
1804.694
1814.666
1824.636
1834.607
1844.578
1854.548
1864.518
1874.489
1884.459
1894.430
1904.400
1914.371
1924.343
1934.312
1944.283
1954.254
1964.225
1974.195
1984.166
1994.139
2004.108
2014.079
2024.048
2034.019
2043.990
2053.961
2063.931
2073.902
2083.873
2093.843
2103.814
2113.785
2123.755
2133.726
2143.697
2153.670
2163.641
2173.613
2183.582
2193.553
2203.524
2213.494
2223.465
2233.435
2243.406
2253.376
2263.348
2273.318
2283.288
2293.259
2303.230
2313.200
2323.172
2333.140
2343.110
2353.083
2363.052
2373.022
2382.993
2392.963
2402.935
2412.905
2422.877
2432.846
2442.817
2452.789
2462.761
2472.729
2482.700
2492.670
2502.641
2512.612
2522.583
...
4516.719
4526.690
4536.660
4546.634
4556.602
4566.572
4576.543
4586.513
4596.484
4606.455
4616.425
4626.396
4636.367
Do you have any idea about the source of the issue ?

Thank you very much,
Pm
So we're seemingly running at 100.3fps (9.97ms per frame). Not a huge error.
Frame rate and exposure time are always set as a multiple of the line readout rate, which is currently defined as 19.5usecs for the up to 120fps mode. When I get a chance I'll see if we have an error in that defined value. There was an error originally with the v1 sensor as they were set based on a 24.8MHz clock when it was actually using 25MHz.

The 5 seconds is from requesting capture start to clearing the capture request. I'm surprised that it is 400ms short, but it depends on exactly when the timer is started and stopped. Adjust your -t value to compensate if it's that big a deal to you.
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

powergravity
Posts: 32
Joined: Sun Dec 25, 2016 12:44 pm

Re: High rate camera for Pi 3

Sat Dec 31, 2016 12:35 pm

Thank you for your advices.

Do you have any suggestion about the way to start the recording as I have mentionned in my previous post:
I think you've missed the fact that this is a rolling shutter sensor (in common with almost all CMOS sensors >1MPix). That means that the lines aren't all being exposed at the same time, so what event would you want to synchronise to? Frame start (end of exposure/start of readout of the first line), Frame End (end of exposure/start of readout of the last line), or somewhere in between?
There is an option in raspivid to trigger off various events, but I don't believe GPIO is currently supported. It only triggers a signal to the GPU to start recording, it doesn't synchronise the low level sensor to the signal.
I am not familiar with camera sensors so I didn’t have any idea that I will have rolling shutter. Is there a way to avoid it? The main data logger code is started from a hardware button. Every loop, I test the Boolean value of the button and if it is true, I start to record all the data. So I would launch the camera recording with the same button.
I have read some topics about external button for raspicam (as viewtopic.php?t=77095&p=550289,...). Why I could not use it in my project?

Thank you,
Pm

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aTao
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Re: High rate camera for Pi 3

Sun Jan 01, 2017 5:27 am

Gonna get way more bang for your buck with 2 laser range finders under the bike. Would have gone for ultra-sonic, but there would need to be a speed correction.
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powergravity
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Re: High rate camera for Pi 3

Tue Jan 03, 2017 10:31 am

Hi,

Best wishes for 2017 :)
Gonna get way more bang for your buck with 2 laser range finders under the bike
Good idea but after having ever tried this method it is too sensitive to the road irregularities.

Is there a way to perfectly know the time of the first frame to be able to adjust with the arduino data logger measures?

Thank you,
Pm

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aTao
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Re: High rate camera for Pi 3

Tue Jan 03, 2017 12:14 pm

powergravity wrote:Hi,

Best wishes for 2017 :)
Gonna get way more bang for your buck with 2 laser range finders under the bike
Good idea but after having ever tried this method it is too sensitive to the road irregularities.

Is there a way to perfectly know the time of the first frame to be able to adjust with the arduino data logger measures?

Thank you,
Pm
A simple synchronisation method could be to place an LED (or several) in the field of view, control this from the Arduino and you should get pretty accurate timings. You should also be able to use it to determine the image distortion from the rolling shutter.
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powergravity
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Re: High rate camera for Pi 3

Fri Jan 06, 2017 1:32 pm

Thanks for your answer. I have thought about it and I have some questions.
The idea is that when I will press the button to start dataloguer acquisition on the arduino in the same time the video will start to record on the Pi. I am considering 2 ways to proceed:
- connect an input GPIO to the datalogger switch using a voltage divider to convert 5V to 3.3V
- connect an input GPIO to a digital output of the Arduino also with a voltage converter and start the recording with a rising signal
Which one seems you the best?

Thank you,
Pm

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aTao
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Re: High rate camera for Pi 3

Fri Jan 06, 2017 3:02 pm

powergravity wrote:Thanks for your answer. I have thought about it and I have some questions.
The idea is that when I will press the button to start dataloguer acquisition on the arduino in the same time the video will start to record on the Pi. I am considering 2 ways to proceed:
- connect an input GPIO to the datalogger switch using a voltage divider to convert 5V to 3.3V
- connect an input GPIO to a digital output of the Arduino also with a voltage converter and start the recording with a rising signal
Which one seems you the best?

Thank you,
Pm
Ahh, the old who is boss question....

As well as start, you also have a stop signal?

so, if switch is boss then both Arduino and RPi need to monitor switch
IF Arduino is boss then Arduino monitors switch and instructs RPi to record/stop
If RPi is boss then RPi (uses keyboard?) instructs Arduino to start/stop.

My choice would be RPi is boss, since you may find you are typing at it a lot during set-up and data retrieval, so a keyboard shortcut for the start/stop switch is possible.
Also pre-rolling a video record has many merits, think film claperboard and the director shouting "Film, Camera, Action". The action is the datalogger starting.
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