WIRIS Agro – Crop Water Stress Index camera

Workswell’s WIRIS Agro is the first device of its kind designed to map water stress across large areas in the field of precision agriculture. The aim of this method and device is to determine the value of water stress in the plant stand. For example, this information may be used to determine yield maps, optimize irrigation, or control water management remedies. Camera offers LWIR band sensor (640×512) and 10x optical zoom RGB camera with resolution full HD (1920 x 1080 px).

The crop water stress index (CWSI) was developed (in 1981) as a normalized index to quantify stress and overcome the effects of other environmental parameters affecting the relationship between stress and plant temperature.
Workswell CWSI Camera
CWSI camera - Crop Water Stress Index

Crop drought – actual and real value

In the dry season what we are usually interested in is the actual effects of drought on crops. These impacts are not only dependent on the condition of the so-called climatic drought, but also on the groundwater drought, the size of the plant root system, etc. Measuring the water stress of plants with WIRIS Agro will help you to determine the actual and real effects of drought on the crop.

A CWSI of 0 indicates no water stress, and a value of 1 represents maximum water stress. The cropwater stress that signals the need for irrigation is crop specific and should consider factors such as yield response to water stress, probable crop price, and water cost. Reginato and Howe (1985) found that cotton yield showed the first signs of decline when the CWSI average during the season was greater than 0.2. [1], [2]

Potential yield maps

Based on the value of water stress, an approximate potential yield map can be determined. Obviously, the more plants are hit by drought, the lower their yield. Worksell CWSI Analyzer software, that comes in bundle with WIRIS Agro, makes it possible to generate potential yield maps from a large number of images across many hectares in a very short time (Challenging calculations common, for example, for orthophotogramers are not needed).

With WIRIS Agro you can get actual values of crop water stress during the flight, or you can use the collected data to create an overview map. By comparing yields from different years depending on water stress, a potential yield map can be created according to the current water stress value.

Workswell CWSI Camera
CWSI camera - Crop Water Stress Index

WIRIS Agro – main benefits

Although there are many uses, we can divide the main WIRIS Agro usage into these three applications:

✅ Water status monitoring – To monitor water stress, ie. the lack of water that the crop is exposed to during the growing season. And regardless of whether the crops are irrigated or not. Special colour map “Crop” and “CropStep” are avaible.

✅ Manage irrigation management – Irrigation system optimization both in terms of determining suitable locations for the location of soil sensors and in terms of structure optimization. Special colour map “Water” and “WaterStep” for that application are avaible.

✅ Phenotyping – Different plant varieties are susceptible to the amount of water available. The WIRIS Agro will help you determine how often the plants of a given species are in water stress, compared to plants of other species.

Software included – CWSI Analyzer

Workswell CWSI Analyzer is a desktop software used to processing of CWSI images. It allows setting of individual parameters necessary for correct calculation of CWSI, both tabular and additional measurement. The software includes predefined most common crops where table values are entered directly. The big advantage of the software is the ability to process hundreds of images at once (mass data processing).

The software is supplied free of charge to the WIRIS Agro.

CWSI camera - Crop Water Stress Index

Sources
[1] Jackson, R.D., S.B. Idso, R.J. Reginato, and P.J. Pinter Jr. 1981. Canopy temperature as a crop water stress indicator. Water Resources Research 17:1133
[2] Plant stress mesurement – en.wikipedia.org/wiki/Plant_stress_measurement

CWSI Partners

CWSI Camera key features description
CWSI onboard processingEvaluation of Crop Water Stress Index onboard
Operating onboard systemCWSI OS for full real-time data streaming and evalution during the flight
- operating system ensures the full access to all camera functions
- easy camera control via S.Bus, CAN bus, MavLink, RJ-45 or Trigger
10x Optical Antivibration zoomFull HD 10x optical zoom camera with anti-vibration compensation
CWSI camera specification
CWSI sensor resolution640 x 512 pixels
CWSI evaluationWorkswell patented CWSI camera technology based on crop water stress index (normalized to value from 0 to 1) brings information about the crop stress and crop water management on large areas. The information can then be used to determine yield maps, manage irrigation or implement water management related remedies.
FPA active sensor size1.088 x 0.8705 cm
Type of sensorLWIR band sensor
CWSI evaluation range0 – 1 (1 means very stressed)
Temperature sensitivity0.03 °C (30 mK)
CWSI calibrationYes, calibrated for different ambient temperatures
Field of view of the lens45°
CWSI Colour-map4 colour maps for CWSI and Water management evaluation
CWSI range settingsAutomatic, manual or span
CWSI digital zoom1 – 14x continuous
Software CWSI analyzerYes, included in the package
Digital visual camera
Resolution1 920 x 1 080 pixels (Full HD),
1/3” sensor,
Auto white balance,
Wide dynamic range,
Backlight compensation,
Exposure and Gamma control
Optical zoom10x optical zoom with vibration compensation
View angleUltra zoom 6.9° - extra wide 58.2°, focal 33.0 mm - 3.3 mm
Noise reductionSpecial 3D noise reduction function
FocusAutofocus with Direct Focus Zoom synchronization
Memory and data recording
MemoryInternal high-speed SSD 128 GB for image and video recording
External slot for Micro SD card & USB 2.0 for USB stick for taking images
Image and video formatsCWSI JPEG images and Digital camera Full HD JPEG images
Digital camera h.264 encode video HD recording
Full-frame CWSI video recording (raw data recording)
GPS geo-tagging (image & video)
GPS tagging (image & video)MavLink or External GPS or DJI A3 controllers compatible via CAN bus
Interfaces & real-time remote control
10-pin digital portS.Bus
CAN bus (compatible with DJI M600 and A3 controllers)
MavLink
External GPS connectivity
External trigger
Ethernet (RJ-45) portVideo streaming and camera control (optional on request only)
Micro USB 2.0 portMass storage
Camera control and video streaming (optional on request only)
USB 2.0 portKeyboard connection for in-house WIRIS camera control
Remote control systemCWSI OS ensures real-time control of all camera functions during the flight
Remote control optionsS.BUS protocol
CAN bus for real-time control on DJI M600 and GPS geo-tagging
RJ-45 for wireless uplink installation (video streaming and camera control)
Protective filter on lensFilter protects the lens against external damage during the flight
Camera functionsMeasurement functions:
- online CWSI evaluation
- spot CWSI evaluation (Centre)
- area CWSI evaluation (Max and Min)
Periodic capturing:
- capturing CWSI image and Visible image simultaneously
Camera modes visualizationFull-screen mode, Picture-in-Picture, Full Dual-screen, Dual-screen
Micro HDMI video output1 280 x 720 pixels (720p), Aspect ratio 16:9, Micro HDMI video output
Software & SDK
Desktop softwareAdvanced Workswell CWSI analyzer for CWSI evaluation
Power supply, weight & dimensions
Input supply voltage9 – 36 VDC, Coaxial 2 x 6.4 mm, outer shell - GND
Power dissipation (avg.)12 W
Weight< 430 grams
Dimensions (L x W x H)83 mm x 85 mm x 68 mm
Mounting2 x 1/4-20 UNC thread (1x bottom side, 1x upper side)
Housing materialDurable aluminium body for long-time measurement stability
Environmental
Operating temperature range-10 °C to +50 °C
Storage temperature range-30 °C to +60 °C

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