Unmanned Aerial Vehicles (UAVs) or drones have become very popular and I’ve had great privilege to research the potential of these tools in broadacre farming. See my Nuffield report here.
I’d like to share how imagery from drones complements that from Satamap.
Below is a Satamap image showing biomass variability in chickpeas caused by water logging. Following is an image captured from a Canon camera (S110) in an SenseFly eBee in the same paddock on roughly the same date. See the red square for location of image.
Water logging in chickpeas – Satamap image
The Satamap imagery is displayed at a resolution of 15 m where as the drone imagery is around 4 cm – a massive difference. The Satamap image accurately exposes all areas of water logging as lower biomass.
In addition, the drone imagery can see individual plants and tramlines. Of particular interest the rows that were planted closer together have survived the water logging event better then all others. Note the blue arrows. This is detail that is not detected from the Satamap imagery.
UAV image showing water logging in chickpeas – courtesy of Australian UAV (www.auav.com.au)
Now lets look at cost – to map the entire 220ha paddock with the drone may have cost $990 (at $4.50/ha) which is the total of a one year subscription to Satamap for a whole 3+ million hectare tile updated every 16 days. Of course there is value in both datasets but of a different kind. Applications of drone data such as identifying weeds in crop, counting plant stand, 3D modelling of crops are all exciting applications reserved for drones.
In summary, the data collected from these two different platforms has totally different scope and work in parallel rather than competing.
iPads are by far and away the most popular platform Satamap is used on. Where you have reception this works great, especially with the GPS locator enabled. The issue some face is in areas where there is no reception. As Satamap is web based it will just not work without reception. If you are going into an area with unreliable reception we have devised a process to get your imagery working offline. It does take some forward planning but works quite well. It’s best shown in the video below.
Text based directions:
These steps are assuming you are using Satamap on an iPad with PDF Maps installed. If you do not yet have PDF Maps grab it from the app store – its free.
Log into Satamap
Select the Export tab in the side menu (Arrow shape)
Click ‘Select Region’
A box will appear over the map, you can adjust the size of this box and move the map around so that the area you want to export fits within its bounds
Select the data you want to export. There are 6 options. Three for the image on the left and three for the right side of the slide. If you want the Satamap VI image select the Rendered option.
Click generate URL
Copy this URL by clicking on then holding. Press Select All, then copy.
Choose ‘Maps’ from options at bottom of screen
At the top right is a ‘+’ sign, press this
Under ‘From the Web’ paste the URL in this box
It should download and process
It will then be available in the Maps list for you to select
Up until recently we had 15 metre pixels for the Natural Colour but the Satamap Vegetation Index was 30 metres. Now both types of imagery are displayed at 15 metres. This means that each pixel represents an area of 15m squared on the ground. This is a significant improvement as shown in the example below.
Satamap moves to 15 m pixels. See change from left to right.
This is made possible using a process known as pan sharpening. Basically the satellite captures the red, green, blue and near infrared bands at 30 metres but also snaps a panchromatic (black and white) band at 15 meters. We can do some nice calculations to combine the panchromatic band with the others to generate a map at 15 metres.