revalo
Posts: 1
Joined: Mon Apr 01, 2019 11:51 pm

Ultra high-speed imaging, capturing matrix style bullet time.

Mon May 13, 2019 11:46 pm

We used 16 Raspberry Pi camera modules and a 1/2,000,000th of a second strobe exposure to capture a bullet going through an apple at 16 different angles.

Image

Check out our results and code here!
https://github.com/revalo/pishot

HermannSW
Posts: 1192
Joined: Fri Jul 22, 2016 9:09 pm

Re: Ultra high-speed imaging, capturing matrix style bullet time.

Thu May 23, 2019 2:09 pm

Nice work!

What kind of strobe do you use to achieve 0.5µs strobe pulse length?
Is it a high voltage one shot strobe?
How fast can you generate a 2nd strobe flash after the first?


I ask because I use a 5000lm led with reflector to get very bright single digit µs strobe pulse lengths:
Image


Today I did my first v1 camera (clone) video, before I did use Arducam ov5647 camera:
viewtopic.php?t=235523


One feature of my flash I wanted to use later for taking multiple exposure frames is that I trigger my strobe from GPIO13 through a Mosfet,
viewtopic.php?f=33&t=241151&p=1471498#p1471369
and that allows very fast tuning on/off the strobe, and most importantly, repeatedly.

Just a few minutes ago I took my first global shutter video with v1 camera (of a mini drone propeller rotating at 20000rpm, which is 35.6m/s(!) at blade tips). And the propeller has two blades. Something went wrong with the timing, and I got multiple exposure accidentially ;-)
This is 2MP frame from video capture with double exposure (4 blades instead of 2):
Image


When I have more I will start a new thread on global shutter video capturing with v1 camera.


P.S:
Made little progress today, captured first triple (11µs) exposure frame:
viewtopic.php?f=33&t=241151&p=1472384#p1472384
Image
bookmark list: https://stamm-wilbrandt.de/en/Raspberry_camera.html

https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/fork-raspiraw
https://github.com/Hermann-SW/userland
https://twitter.com/HermannSW

HermannSW
Posts: 1192
Joined: Fri Jul 22, 2016 9:09 pm

Re: Ultra high-speed imaging, capturing matrix style bullet time.

Sat May 25, 2019 9:59 pm

I have it under control, the new thread will be started soon, just for today:
viewtopic.php?f=33&t=241151&p=1472646#p1472646
"2MP frame generated by five 9µs duration strobe flashes, 241µs apart":
Image
bookmark list: https://stamm-wilbrandt.de/en/Raspberry_camera.html

https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/fork-raspiraw
https://github.com/Hermann-SW/userland
https://twitter.com/HermannSW

TomLer
Posts: 1
Joined: Thu Jun 13, 2019 7:15 pm

Re: Ultra high-speed imaging, capturing matrix style bullet time.

Sat Jun 15, 2019 10:27 pm

This is really amazing, thank you so much for sharing.
I'm curious if you have more information on how the physical wiring between the devices was done?

HermannSW
Posts: 1192
Joined: Fri Jul 22, 2016 9:09 pm

Re: Ultra high-speed imaging, capturing matrix style bullet time.

Sun Jun 16, 2019 10:45 pm

I am not sure whether revalo still monitors this forum, you can find the wiring description in his github repo:
https://github.com/revalo/pishot#gpio-based

Yes, the work of revalo's team is amazing, capturing a single point in time with many Raspberry v1 cameras.

You can do amazing stuff with a single camera as well, just today I captured a roughly 100m/s flying pointed airgun pellet with 9kHz PWM frequency and 8.33µs strobe pulse length in this 9000eps frame (exposures per second) from 90fps v1 camera video ten times:
Image
bookmark list: https://stamm-wilbrandt.de/en/Raspberry_camera.html

https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/fork-raspiraw
https://github.com/Hermann-SW/userland
https://twitter.com/HermannSW

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