What is a CRP and what does it do?
Any object reflects and absorbs certain amounts of light. Depending on what the object is made up of it may reflect more or less of certain bandwidths in the electromagnetic spectrum. Plants for an example reflect Green light heavily while absorbing Red and Blue wavelengths. This reflectance reading can vary based on the environmental conditions present at your survey location.
The Calibration Reflectance Panel serves as a ground truth for reflectance values at your survey location. You can measures the amount of light reflected and absorbed by an object that has known reflectance values. With this we can calibrate the source data to the exact environmental conditions on site. Without a calibration process, data captured at different times cannot be accurately compared due to the environmental changes that were not compensated for.
Currently calibration panels are only compatible with the Micasense Red Edge Sensor and not the Parrot Sequoia.
Calibration Panel Data Collection
On the reflectance panel there is a White square that is actually made up of many different shades that have know reflectance and absorption levels to use in the calibration. Before each survey with your Micasense Red Edge sensor you must take images of these calibration panels to pair with your source data for the flight.
- Place your Calibration Panel on flat ground
- Be sure that no shadows are present nearby the panel that could change the calibration readings
- Use your drone to capture an image of the Calibration Panel
You can leave these calibration panel images on your sensor memory card or transfer to a saved location before flying your survey. Once complete make sure to pair the calibration panel data with the source imagery for use in the upload process.
Uploading Survey with Calibration Panel Data
The steps to uploading your Micasense data with Calibration Panel Data follows nearly the same process as a standard upload. However there is one additional step to add the calibration panel images that we will discuss here.
- When you are uploading MicaSense data to PrecisionMapper you'll first need your imagery that was taken with the MicaSense sensor.
- In Step 2 you will see a "Radiometric Calibration" option at the bottom of the screen
- This is where you'll upload your panel data. The images will be labeled 1-5 each band has its own image. You'll need to browse for your first image and import it into the "Blue." You'll also need to upload at least one image per band.
- Once you have all of your images calibrated and saved hit the "Next" button for you to continue with the uploading of your survey.