The Quividi solution works with any video sensor producing a regular video stream. In the majority of cases, a USB webcam is the simplest and cheapest sensor to recommend. Some other environments might lean towards IP cameras.
Choice of a USB camera
VidiReports works with any webcam using the UVC norm (ie the video device norm that makes a camera be automatically detected by most operating systems), whether on a USB2 or USB3 port.
When you select a USB webcam, consider these elements:
- Field of view: by default, most consumer webcams come with 60-80° horizontal field of view, which is appropriate in places where the traffic doesn't come close to the camera.
It may be appropriate to chose a field of view closer to 120° if the audience can see your point of interest from the sides, such as in retail alleys or when you measure a shop window.
You will rarely find field of view beyond 100° on consumer webcams, and you'll then want to consider webcams with a choice of lenses, such as those from ELP. Lenses are expressed in mm of the focal length, and the smaller the value, the wider they will see (although the sensor size and lens coverage also play a role). For instance, a 1.4mm lens will deliver a 140° horizontal field of view on most webcams, while a 3.6mm will deliver 60° (more info here).
Remember, with VidiReports, that the wider the field of view, the less detection distance you'll get (more details here)
- Attachment options: you'll probably want the webcam to be attached to the point of interest you're measuring, or even hidden from the view of the audience.
Consumer webcams are designed to be placed on top of screens, but not to solidly attach to them. You may want to favor those with a full flat front surface, so that they could be glued behind the facade with just a hole to let the lens see through. Note however that in that case, you won't be able to slightly tilt the camera down or sideways to be directed towards where the main traffic happens and you'll have to ensure that the lens is perfectly positioned with respect to the hole.
Alternatively, the semi-pro webcams such as those from ELP come with a bracket offering more leeway to point the camera in the right direction.
In the case of a measurement through a glass window, you should favor cameras that can be attached to the window itself because of their flat surface, either via double-sided tape, or via succion cups (more info here).
- Resolution: most webcams these days come with a 1920 x 1080 resolution which will let you detect faces at ~10m distance with a standard lens, which is the standard. Cameras with lower resolution will lose on face distance detection (more details ), which may be acceptable when audience can't be far anyway, and will require less CPU to run. Note the body detection in Quividi ("footfall") will work whatever the resolution (eg 640 x 480) and won't be influenced by it.
- Autofocus or not: most webcams perform an autofocus automatically, so that if a person comes close it remains in focus. This is not needed by VidiReports, but is not per se a problem (although any moving mechanism in a device will wear out over time). Sometimes, you might want to keep a fixed focus, in which case, only cameras with screw-on lens will natively ensure this (a drop of superglue will ensure the focus isn't change by mistake).
- Image quality: A good image quality has some influence on the detection of faces, and this quality generally depends on the use of several glass lenses. It's a good idea to check for "[Manufacturer] [Camera model] review" over the Internet to see what other users think of the picture quality for the model you're considering.
The more expensive USB models sometimes provide "wide dynamic range", ie the capacity to still see facial traits in case of backlighting (see example here).
- Size: Most webcams are less than 10 cm in width, 3 cm in height and 4 cm in depth (excluding their attachment system). You may break loose the attachment system if you're embedding them inside a casing. Sometimes you'll only have the option to consider much smaller camera boards, such as the ones used in laptops. Just then search for "webcam board USB" on the Internet.
- Ease of supply: cameras from little known companies might be difficult to supply, not maintained over time, or come with custom taxes. Consumer webcams from Logitech, or Microsoft are commonly found online or in consumer electronics stores.
- Not UVC-compliant cameras, and cameras requiring specific drivers (typically professional cameras, and 3D or dual-lens cameras) are NOT supported.
- Avoid selecting 180° lenses that will result in the image being completely distorted. VidiReports requires images that resemble what a human eye will see.
- Microphone in webcam is always present, but not needed by VidiReports.
- A few tiny, cheap home surveillance cameras come with USB cords to power them, but they will not use the USB cord to send the video signal to the PC (they'll use wifi instead, and are truly IP Wifi cameras - see next section).
- Limited simultaneous number of webcams: while VidiReports isn't limited to the number of streams it can analyze, the problem lies on the electrical power that a PC can deliver to several webcams connected to it. Experience shows that beyond 2 webcams, you run the risk of often losing signal.
- USB cord extensions: webcams come with cords that are between 0.8 and 2m in length. If you need more cord distance (for instance in a screen totem), be sure to use an active (powered) USB extension cord.
Choice of an IP camera
There are cases where a USB webcam will not be appropriate. This is essentially the case when:
- the camera will be used outdoors
- the processing unit will be distant from the camera
- you want to have multiple video streams processed on the same (beefy) PC
- the resolution needs to be superior to 5 megapixels for long distance detection
- the camera needs to offer a specific zoom
- the user needs to have a separate access to the camera stream for monitoring
In those cases, it is recommended to use an IP camera. IP cameras use generally either the MJPG protocol or the H264 (also known as MP4) over RTSP protocol, both of which being supported by Quividi solutions.
There is a vast quantity of IP cameras to choose from, but note that these cameras tend to be more bulky than webcams. We recommend making sure that the model you are considering would have its RTSP URL be listed on this page.
When selecting an IP camera consider the following criteria:
- Outdoor or indoor: outdoor cameras are designed to resist rain, and extreme weather conditions and generally follow the IP67 waterproof norm. They are often housed in a dark dome, which is OK when the point of interest is large and far away (eg a big billboard). By contrast indoor IP cameras come in all forms and shapes, but rarely as parallelepipedic as the USB webcams. A few of them will deport the lens at the end of a cable and do the processing in a separate tiny box, such as those from Axis.
- Power over Ethernet: IP cameras can often be powered by the Ethernet cable, which avoids adding an electrical socket, making installation easier. You'll probably then need to use a specific router offering POE injection.
- Resolution: most IP cameras have resolution starting at 1920 x 1080 these days, and many offer much higher resolutions. As with the USB webcams, more pixels will lead to longer detection distance, but require more CPU (more info here)
- Varifocal lens and motorized cameras: these options cost a bit more but offer the advantage of letting you aim and zoom at the scene where the audience walks for the setup phase, even after the hardware installation. However, you should not touch the settings once the wanted scene has been selected, because VidiReports needs to work with a stable image to deliver consistent results.
- Brand name: IP cameras from Axis, Panasonic, or Vivotek have proven to work well with Quividi and shown robustness, but many respected brands abound on this market. As with webcams, you'll want to read reviews before selecting a brand and a model.
- IP cameras introduce some latency, i.e. VidiReports will get the image between 0.5 and 3.0 seconds after action took place. This may be problematic if you want to calculate Audience by content or if you want to do triggering depending on the audience.
- Wifi: many cameras can connect via Wifi, and VidiReports will work with this, but Wifi often runs into signal loss and it is generally preferred to connect the IP camera via an Ethernet cable.
- "Smart" cameras: some higher-end IP camera models now offer to do computer vision right inside the camera. Quividi does runs on computer chips and will not leverage the embedded algorithms within those cameras, whose performance is unknown. That's not to say that you should not select those models, but you'll probably be finding similar specs without the computer vision from the same brand at a cheaper price.
- Existing IP cameras: While the Quividi solution will work with most IP camera, the ones initially set up for security purposes are rarely placed nearby points of interest. As such, they can be used for counting passages with the Footfall algorithm, but will not make it possible to count faces turned towards that point of interest.
- Multiple IP cameras processed on the same PC: As opposed to USB cameras, a same PC can handle multiple instances of VidiReports, each processing the stream from one IP camera (more info here). For instance, a store could have 1 PC in the PC bay processing the images from 10 IP cameras spread throughout the store. In this case, you'll want to envisage server-type PCs with powerful CPUs and a LAN architecture offering enough bandwidth.
- Home surveillance cameras have blossomed recently on the market and their low cost and tiny form factor are tantalizing, however they generally can not be used with VidiReports because only the application provided by the manufacturer will have access to them, and these will not support the RTSP protocol.
- Concurrent access to an IP video stream: while it may be an advantage to have multiple applications accessing the video stream simultaneously (something that is impossible with USB cameras), it puts the onus onto you to ensure that access be restricted solely to specific tasks such as maintenance, and avoid that these streams be used malevolently and the audience privacy be jeopardized.