Using our Bluegrass Fields and Pix4DFields can I detect the red rice disease in fields of rice? If yes which output should I use and what flight parameters should I fly?
Thank you for contacting Pix4D Technical Support. Questions of fertilizer use and disease detection are the domain of expertise of an agronomist, and we encourage you to consult one if you have specific questions on this topic. However, I am going to give you some ideas of what can be done.
Using Pix4Dfields you can get the following outputs: orthomosaic, digital surface model, vegetation index maps, zonation maps, prescription maps, field boundaries, annotations, and the pdf report.
Some remote sensing concepts
An image is generated from multiple factors:
· Illumination from the sun: we recommend to use the sunshine sensor
· Reflectance from the plant: we recommend to use reflectance target images and radiometry correction option while processing
· Interpretation by the sensor
What is essential in plant diseases is that the r eflectance containing information about the plants is related to the health or content of chlorophyll on the plant.
A plant has chlorophyll and the plant with more chlorophyll (more healthy) will have two more prominent effects:
· Will absorb more red (and blue) that an unhealthy plant
· Reflect more near-infrared energy than a sick plant
Therefore, we recommend generating the NDVI index (Normalized Difference Vegetation Index), which is calculated based on the NIR and Red bands. NDVI index will give you values from -1 to 1. A zero means no vegetation and closes to +1 indicates the highest possible density of green leaves. With the NDVI you can select specific areas where you can do your detailed scouting and testing to confirm the problems.
Also, plant stress analysis is depicted in the NDVI vegetation index. Stressed crops will have less NDVI than crops that are healthy.
You probably know that Pix4Dfields support different types of cameras:
· RGB: red green and blue, which is what we can generally see with our eyes
· Multispectral camera (Good to calculate the NDVI because will give you a good response on the red and infrared)
The uses of the indices will always depend on your interest. After generating the index, and for monitoring what our users normally do is they generate zones and use the prescription tool.
Let’s say that I would like to see my area of interest in 3 zones based on my NDVI, so I get this:
The zonation and prescription tool is designed for fields where you are looking to produce variable rate application maps for machinery (e.g. fertilizer spreaders, seeders, etc.) In this example, (red areas) I know from my NDVI that the plants are not so healthy so might be there are weeds or something else wrong, so I can will add more weedicides in the red zone , and I will add less weedicide in the yellow areas because my NDVI showed me that the plants look good.
You can start collecting flown field maps, records or models to compare the behave of the plant during different times of the year.
In agriculture, we do recommend using multispectral images because the infrared band tells us about the chlorophyll in the leaf.
In this link, you can see step by step of how to use the software, and some general information like computer requirements, and release notes.
Here you find information about the image acquisition for general cases, flat terrain with agriculture fields, and forest and dense vegetation.
Here our link to videos of how to use Pix4Dfields with subtitles in English, Spanish, and German
We are going to have a webinar tomorrow, maybe you can join https://www.pix4d.com/pix4dfields-webinar-instant-processing-for-precision-agriculture My colleagues will give detail to a user’s experience with RedEdge-M and Pix4Dfields.
If you are using Parrot Fields, please check here
Hope this information was helpful for you.