On Sun, Mar 03, 2019 at 06:11:38PM +0100, leopold zyka wrote:
Hi,
Hey Leopold,
I have some usecases where I would need a lot of cheap webcams.
What resolution and what framerate are we talking about?
One application is 3D scanning. The project 3DScan uses 100 Raspberry Pi cams: http://www.pi3dscan.com/ Here you find the costs of the hardware: http://www.pi3dscan.com/index.php/cost
So I am thinking how we could make this cheaper.
Really depends on the number of cameras as well as the resultion, framerate and total bandwidth you have in mind.
*MIP CSI2* The raspberry PI cams and all the cams used in mobile phones don’t use an USB interface. They use CSI-2 (*Camera* Serial Interface Type 2) with a 15 pin ZIF 15 socket.
A widely adopted, simple, high-speed protocol primarily intended for point-to-point image and video transmission between cameras and host devices
Yeah, unfortunately it is also proprietary and somewhat problematic to handle, but definitely doable.
*USB Webcams?* An alternative to the would be to use USB-Webcams and don’t have 100 hundred decentralized CPUs (Raspberries).
The challenge is you need a multi-port USB interface like this: https://plugable.com/products/usb3c-hub97xxx/
One problem with this approach is that there are no multi-port solutions available.
You can actually stack USB hubs to quite some depth (7 hubs deep device tree) and quite a number of devices per USB port (127 or 255) so you can use a tree of powered (this is important) USB hubs or some of the more expensive 16/28/54 port hubs. https://www.amazon.com/Adapter-Charging-Individual-Switches-Windows/dp/B07FS... https://www.amazon.com/Manhattan-Port-USB-Hub-161718/dp/B0074024XU Note that you are still limited to the total of 5 Gbps for each USB 3.0 port, so your bandwidth for 16 devices will be below USB 2.0 (~300 Mbps) and even less for more
Due to high demand the above product is unfortunately sold out indefinitely.
I assume that there would be also a bandwidth-problem on the PC side.
Yep, see above, you can probably get about 40 USB 2.0 devices at full speed on four USB 3.0 ports.
*Use Raspberry PI Zero?* Using a Raspberry PI Zero would save some money: *https://www.pi3dscan.com/index.php/blog2/45-raspberry-pi-zero-v2 <https://www.pi3dscan.com/index.php/blog2/45-raspberry-pi-zero-v2>*
*Use an ESP32-PICO? *https://www.youtube.com/watch?v=B8Jq0G17WgQ
Maybe it would not work with a cam which has more than 2 MPixels resolution.
This would mainly be limited by the Wifi/BT interface which will not allow you to run more than a few of those at the same place.
*Summary* For me the best would be to have a module where the cam-module already sits on the PCB.
This would save connectors, cables (15pin!) and adaptors. Also I would prefer to have a waterproof case for outdoor usage.
*Any Ideas???*
Let's first specify the resolution, frame rate and total bandwidth required for your applications, then we can talk interfaces and sensor/camera solutions. Best, Herbert
_______________________________________________ Metalab mailing list Metalab@lists.metalab.at https://lists.metalab.at/mailman/listinfo/metalab