Free satellite images for Ont. producers

Free satellite images for Ont. producers
Mar 10, 2021

Researchers at Mohawk College investigated the potential for open-source images to help improve crop productivity 

By Jackie Clark
Staff Writer

A research team at Mohawk College investigated the potential to use open-source satellite imaging to monitor crop health. Sentinel-2 mission satellites provide free imaging with high spatial and temporal resolution.

To test the effectiveness of the images, researchers observed “the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Red Edge (NDRE) crop health indicators,” Soham Shah, professor at Mohawk and lead on the case study, told

On average, the imaging showed eight pixels per acre “which shows that the satellite imagery we used had a spatial resolution of approximately 17mx17m. This is a fairly high spatial resolution and thus can be used to monitor individual farms,” Shah explained.

However, challenges still exist when using these images to monitor crops.

“We were hoping to be able to monitor the farms on a weekly basis throughout the growing season, since the Sentinel 2 satellite’s revisit time in mid-latitude regions is 2-3 days,” Shah said. “NDVI values throughout the growing season were measured for 3 counties in Ontario which were studied, but the temporal resolution varied for each county.”

The team measured values in Grey, Lambton, and Oxford counties.

“For Lambton County, there were gaps in the data with the months of April and August missing due to cloud cover present throughout those months, he explained. “The cloud cover was less for Oxford County, where we could gather data at least once every month. The highest temporal frequency of data collection was possible in Grey County, where we could gather bi-weekly or even weekly data for most of the months in the growing season.”

So, “cloud cover is a very important factor and it can cause temporal gaps in the data and continues to be a limiting factor in using only public domain satellites in precision agriculture,” he added.

Overall, the case study determined that open-source data has the potential to reduce the need for individual farms to invest in remote sensing, therefore making precision agriculture more affordable.

“Farmers can use publicly available remote sensing tools such as the Sentinel 2 Image explorer created by ESRI, which is quite user friendly and allows the farmer to look at the latest imagery data that can be filtered by cloud cover to see many different crop health indices rendered for their farm,” Shah explained.

Moving forward, increasingly accurate, publicly accessible imaging can help improve crop productivity.

Vonkara1\E+ photo

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