🛰ESMERALDA uses free satellite data collected by Europe's Copernicus Sentinel satellites. 📡
Considering that the data collected by the Sentinels has a spatial resolution of 10 metres, this is impressive, especially when you realise that this is being done continuously across the globe. The resulting volumes of data are equally staggering. However, for some practical applications, such as mapping access to restoration sites, this spatial resolution is often not good enough, as a path two to three metres wide is unlikely to show up in the collected image. Also, if you are interested in individual trees, the very young and small ones cannot be seen. Many organisations are trying to overcome these disadvantages by using drones to capture images with much higher spatial resolution.
This is a valid approach, but it has some drawbacks:
1. you have to buy the drone, which can cost thousands of dollars
2. the drone pilot has to travel to and from the area of interest
3. the data collected is usually only in the red (R), green (G) and blue (B) spectral bands, which offer limited analysis capabilities
4. local data volumes tend to be very large and need to be stored and processed; and
5. drone imaging is feasible for a few hundred hectares, but does not scale well to thousands or even hundreds of thousands of hectares.
🔭 Very high resolution (VHR) satellite images: It does not have the aforementioned drawbacks and is easily accessible through ESMERALDA TRACKER. The most obvious differences with Sentinel data are the spatial and temporal resolution and the cost. The spatial resolution goes down to 0.53 metres and images are only acquired on request. The customer has to pay for this additional data option. Prices can vary, but are usually no more than a few dollars per hectare when a satellite is ordered to take a new image. The price drops significantly when images from the archive are accessed. Compared to drone imagery, satellite data is very attractively priced from our perspective and is scalable to very large areas.
In ESMERALDA-TRACKER, accessing this type of satellite data is as easy as accessing any other data. The user simply needs to define the area of interest by drawing a bounding box on the map, decide on the desired time period and specify the amount of acceptable cloud cover. The system then accesses the archive of a commercial satellite data provider and retrieves the imagery, which is automatically delivered to the ESMERALDA TRACKER layer tree. The data is automatically geo-referenced and, due to the multi-spectral bands of the image, can be analysed like any other satellite data. The development roadmap for ESMERALDA-TRACKER includes access to satellite tasking, allowing users to acquire new data sets if the archive does not provide sufficiently detailed or recent data. 🌏📚