To allow for a qualitative measurement of the biometric parameters from a video, we ask to meet the guidelines below. Parameters marked with 'required' must be met. Parameters marked with 'optional' are recommended, but not obligated.
Camera sensor size & pixel size (required)
The camera sensor is the part of the imaging system that is sensitive to light. The size of this sensor plays an important role in the final quality of the image or video. The larger the sensor, the more sensitive it is to light. Larger image sensors have larger pixels, which means less noise, better dynamic range and the ability to obtain more (subtle) information. The size of the sensor should be at least 5.0 mm in diagonal. The size of a pixel (unit cell) should be at least 1.0 μm.
Lens quality (required)
Lens quality is becoming more important with the increasing pixel count on modern cameras. The resolution of digital photos is often limited by the camera lens rather than the resolution of the camera itself. In order to perform a qualitative measurement, the lens should have an aperture of at least f2.8 and be made from glass or an (optically) higher quality material.
Video length (required)
The recording length of the video should be at least 15 seconds and should not exceed a length of one minute. A video length of 30 seconds is recommended.
A video length of 30 seconds provides a nice trade-off between accuracy and processing time.
Frame rate (required)
The video frame rate should at least be 30 fps and should not exceed 60 fps. The recommended value is a recording frame rate of 30 fps.
Higher frame rates may lead to a marginal increase in accuracy, but highly increases upload and processing time.
In case you are not sure the video is recorded correctly, we recommend using a tool like https://www.metadata2go.com to verify the video's metadata. The r_frame_rate field should contain a value between 30 and 60 fps.
Video resolution (required)
The video resolution should be between 720p and 4K. We recommend a video resolution of 1080p.
Higher video resolution will not lead to higher accuracy levels, but will increase upload and processing time.
Video codec (required)
Videos should ideally be recorded using the commonly used H.264 (MPEG-4) or H.265 (HEVC) codecs. When integrating into a web-based platform, the above codecs might not be supported depending on the browser. In this case, the VP9 codec should be used.
Other video codecs should not be used.
In case you are not sure the video is recorded with the correct codec, we recommend using a tool like https://www.metadata2go.com to verify the video's metadata. The codec_name field should contain one of the codecs mentioned above.
Video bit rate (optional)
When recording a video, you may have the option to provide some video encoding settings. One of those settings is the video bit rate. To make sure we don't loose valid pixel data during the video encoding process, we recommended to set the video bit rate to 8Mbps or slightly higher.
A value of 8Mbps is a standard video bit rate value for a 1080p video. Values above 25Mbps don't provide any significant changes in accuracy levels, but will increase upload times.