StereoPi v2

by StereoPi

The open-source stereoscopic camera based on Raspberry Pi with Wi-Fi, Bluetooth, and an advanced powering system

View all updates Mar 04, 2021

A look at the features and advantages of the new HQ-based StereoPi

by Eugene Pomazov

A brief look at the history of Raspberry Pi camera modules:

  • The V1 was the first camera module, announced in 2013. It had a 5 MPx sensor (OV5647) and tiny pinhole optics.
  • The V2 is the next generation, released in 2016. It uses an 8 MPx Sony IMX219 sensor. Compared to the V1, it has a higher resolution, better sensitivity in low light conditions, and higher FPS at high resolutions. By the way, our Camera Kit includes a couple of wide-angle cameras based on this Sony sensor.
  • The HQ Camera was released 2020. It could have been named V3, but the Raspberry Pi Foundation decided it needed a new name, from the abbreviation for High Quality. It's the most advanced camera module yet.

The HQ camera has a lot of new features

Let’s take a look at the most interesting advantages from the perspective of stereoscopy:

  • A 12 MPx Sony IMX477 sensor means you can get high resolution, 24-MPx, stereoscopic photos.
  • An advanced IMX477 light sensor provides greater sensitivity and contrast. The IMX477 also has a 1/2" (diagonal) sensor that is twice the size of the V2. That means your camera can capture more light.
  • HQ construction allows you to remove the IR filter with no risk of damage to the sensor so you can capture near-IR images
  • Changeable optics with a C/CS mount provides the ability to use literally hundreds of different lenses.

A closer look at HQ’s C/CS mount

  • The HQ camera uses optics with a C/CS mount. This means the lens diameter is nearly 1”. By comparison, the v2 camera optics have a diameter of about 1.4 mm. That means the glass square is ~350 times larger than on v2! Just imagine how much more light the HQ camera can capture!
  • There are hundreds of C/CS lenses on the market, so you can choose the most appropriate for your use case. Raspberry Pi recommends you start with this 6 mm lens or this 16mm lens.

Three tips to help you use optics to improve your photography:

  • C and CS mount type lenses use the same thread type. The difference is the distance from the rear of the lens to the sensor. Each HQ camera has a C-CS mount adapter included, so you can use both types of lenses. As a rule, C-lenses are more advanced and expensive.
  • Both types of lenses are used on IP cameras, so you can find a lot of them on the market. You will be disappointed if you use a sub-megapixel lens with the HQ camera. We recommend 3 MPx or better.
  • If the lens is equipped with an adjustable iris, you can limit the light flow to the sensor, which will also create a depth-of-field effect for your photos. We're now in the territory of classic film photography!

One last feature: Industrial-grade synchronization for two HQ cameras

To get a good stereoscopic image, both cameras need to capture their frames at the exact same time. Unsurprisingly, one of the most common questions we get is about how to keep cameras in sync. Fortunately, the HQ camera has one more exclusive feature: a pair of HQ cameras can synchronize with one another. And, just like high-end industrial stereoscopic and multi-camera devices, they can do so with nanosecond precision by using direct negotiation between the two IMX477 sensors.

Basically, each sensor can act as a primary or as a secondary. When the primary is preparing to capture a frame, it sends a short command to the secondary so that both cameras grab a frame at virtually the same instant.

The XVS soldering pad is used for this camera synchronization. To get both HQ cameras synced, you need to connect these pads and add a few lines to your config.txt. This Raspberry Pi forum thread more detail. (We’ll be adding that information to our Wiki soon.)

You can also use HQ cameras in stereoscopic mode without this hardware synchronization. Even if you fall back to the same type of software sync employed by the v1 and v2 cameras, you will still get millisecond precision. Our experiments have shown that hardware and software sync are nearly indistinguishable, but this may change as applications and techniques evolve to take advantage of what is now a stock feature of the HQ camera.

Conclusion

In summary, HQ camera has a bigger, better sensor; a hardware-synchronization feature; and higher quality, more versatile optics. Note, however, that C/CS optics have more metal and glass in them, so they do weigh more. To handle the additional weight, we designed our new metal HQ housing.

Next up

Q: Is it possible to take ultraviolet photos using HQ cameras?
Q: What are the advanced-adjustment features of the HQ housing?

To be continued! Meanwhile, stay tuned and subscribe!

About the Author

Eugene Pomazov

StereoPi  ·  Realizator  ·   St. Petersburg


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Product Choices

$49

StereoPi v2 Slim

Perfect for DIY ninjas and those wanting to embed StereoPi in a tight space. This board is the same as the standard edition, but without all the bulky connectors - the Ethernet RJ45 jack, GPIO header, and dual USB Type-A connector have not been populated. To use this board, you will need your own Raspberry Pi Compute Module, cameras, and camera ribbon cables. Two short power cables and three jumpers already included.


$55

StereoPi v2 Standard

The world of stereoscopic video awaits! This board is the ultimate interface between two cameras and a Raspberry Pi Compute Module. It comes with all the bells and whistles, including Ethernet, dual USB ports, GPIO header, microSD slot, HDMI output, and more. To use this board, you will need your own Raspberry Pi Compute Module, cameras, and camera ribbon cables. Two short power cables and three jumpers already included.


$185

StereoPi v2 Camera Kit

Everything you need to assemble your camera! Includes StereoPi Standard, CM4 + external antenna, 2 cameras (IMX219, 160 FOV), a TFT screen, a shot button, camera-mount plates, nuts & bolts, 3 jumpers, a 15 cm tripod, and 2 microSD cards with pre-written SLP and OpenCV images!


$25

StereoPi PoE HAT

This board adds Power over Ethernet option to your StereoPi


$55

StereoPi HQ Metal Housing

Metal housing for a couple of HQ cameras with advanced adjustments features. Includes StereoPi HQ housing base + carriages, 2 x HOYA CM500 filters (8.9 x 8.9 x 1 mm), a set of nuts/bolts/washers for assembly, and a tripod. To use this kit you need a couple of HQ cameras and a couple of C or CS lenses.

Credits

StereoPi

We are a small team of geeks who have been making remote-controlled things with livestreaming video since 2010. We've done everything from boats and planes, to robots, copters, and VR helmets. If we can't find the right tools for our projects, we build them ourselves.


Eugene

Sergey Serov


NexPCB

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