Capturing Light Sensor Data
This page describes the various ways to use the DAQ-A-S Light Sensor
The logged data from the light sensor (spectrometer) in the DAQ-A-S models is used in our post processing software to calibrate our camera's images.
The light sensor measures the ambient light spectrum and the reference targets tell us how that light is reflected, so that the multispectral images can be calibrated and compared over time and location.
Mounting the DAQ-A-S Light Sensor
The light sensor can be attached to various locations using our mounting accessories. We also provide the 3D CAD file (here) for the rail mount so you can integrate the DAQ-A-SD into your own design.
Orientation Relative to the Light Source
The diffuser over the light sensor must be illuminated (lit up) by the ambient light source(s). If possible position the white diffuser perpendicular (looking straight at) the light source. If you tilt it off angle that is OK. You want to make sure that the same light source is also illuminating your calibration targets when you capture the image of the targets.
Standalone/Separate Configuration
As long as you connect a 5V power source to the DAQ-A-S it can be used on its own. All 5V USB power banks/stations or USB power sources should be able to power it. It does not have to be connected to a Survey3 camera. If you have an existing capture workflow using PPK or RTK you can continue to use those methods if desired.
Once the LED is green the logging has started. While it is logging you can walk around (or fly your drone) with your Survey3 camera(s) to capture images of the reflectance targets and any other images you desire. The Survey3 camera must be connected to a GNSS and the camera's time zone must be set to GMT-0, to match the DAQ log timestamps. The timestamps are used in post processing to match up the light spectrum logged at the time the image was captured.
Connected to Survey3 Camera Configuration
Using the Survey3 camera cables you can connect the DAQ-A-S directly to 1 or 2 Survey3 cameras. Connecting them allows the camera to use the GNSS in the DAQ, as well as log the camera's exposure to assist with the PPK positional corrections in post processing.
Most of the time you'll likely connect the DAQ and cameras with a short cable length, but if you are using a longer cable keep in mind any shadows that may cover the DAQ (more info below in timelapse section).
Only the 10 in (25 cm) Survey3 cable supports using a single Survey3 camera for power. If you use a longer cable you will need to use 2 Survey3 cameras or external power.
Connecting them together allows you to use the button on the DAQ to capture images. Just perform a quick click to start the image capturing sequence. If the camera interval setting is set to 0, one button press means one picture captured.
You can attach both DAQ and Survey3 to a handheld/mobile tripod mount:
You can attach both DAQ and Survey3 to a vehicle such as an autonomous drone:
You can attach both DAQ and Survey3 to a stationary tripod mount:
Timelapse Configuration
When the light source is moving over time, such as the sun moving across the sky it is important to try and reduce any shadows from shading the light sensor, unless the area the camera is capturing images of is also shaded. Keep the scene being captured and the light sensor in the same ambient light for the best results.
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