Satellite imagery for precision agriculture: Satamap

Satamap is a web based satellite imagery service for precision agriculture. It’s available at satamap.com.au. This is a project I am part of so the following is not an independent review, just a quickly written explanation of this innovative app. I understand my audience is fairly schooled in most things precision agriculture so I’ll skip the marketing talk and get straight to the point.

Today we are launching Satamap. This is a brand new service making up to date satellite imagery available to everyone. Our focus is on agriculture, therefore all imagery is paired with a vegetation index called Satamap Vegetation Index (SVI). It is similar to NDVI but we believe it is better at showing variability in high biomass crops and less impacted by soil colour. The colour ramp we use to represent the SVI values, while in your face at first, is designed to show biomass variability in all crops, at all stages of crop growth at all times of year. The colours remain consistent year round so that, for example blue represents the same as blue and red, red no matter which location or time of year. This is important because the Satamap slider allows any two image dates to be laid over the top of the other and the ability to slide between the two for a direct comparison. The same can be done with the standard colour imagery as well.

Satamap screenshot
Satamap screenshot

This service does not require drawing in of paddock boundaries or limit you to a small area of interest. Subscriptions are based on a 3 million plus hectare tile. It takes 5 minutes to subscribe and you have access to the whole area and an archive back to winter 2013. Imagery is captured at a 16 day interval. Cloud can get in the way at times which can be frustrating but we are working on increasing our imagery availability to reduce cloud impacts. The colour imagery has a resolution of 15 m and the SVI is 30 m. We cover all major cropping regions of Australia.

Satamap works best in an iPad or similar tablet device, but functions equally as well on a desktop computer. Other standard features in Satamap include custom markers, area measurement tools, imagery export and GPS location on the map. All these features themselves could warrant an article, but best to just watch the video to see some of them in action.

Satellite imagery has been available to agriculture and related industries for decades and those that have invested the time and money will attest to the value and significance in this technology but admit that all too much the time and money is often the biggest hindrance. We are aiming to solve these problems with Satamap and bring out the potential of satellite imagery for agriculture. Agronomists, grain traders, farmers, suppliers and more can all benefit from rapid, cost effective access to up to date satellite imagery.

We are in constant development. We are working on offering higher resolution imagery, ground truthing data points, exporting with post-processing and more. Currently only available in Australia, very soon we will be opening up to other parts of the world. Thanks for checking in.

Please check it out at satamap.com.au.

Landsat 8 example using pan-sharpening in Orfeo Toolbox

February this year USGS has sent another satellite up into orbit to continue observing the earth. This satellite, named Landsat 8, provides the same spatial resolution in all bands as Landsat 7. That is one pixel equals 15m pan-chromatic and 30m for all other bands (excluding thermal). In addition, it has a couple extra bands for water, cloud and surface temperature (this link explains the other similarities and differences in more detail).

Here is a sample that I have pan-sharpened using the open source Orfeo Toolbox. Bands displayed are 6, 5 & 2, which is comparable to 5, 4 & 1 in Landsat 5 & 7. This image was capture 27th of May 2013. Most of the bright green paddocks are canola and you can see some of the earlier cereals coming through.

Bands 6, 5 & 2. Extract from scene Path 91, Row 80 on  27-May-2013
Landsat 8: Bands 6, 5 & 2. Extract from scene Path 91, Row 80 on 27-May-2013

More info: As suggested in comments, Spectral Transformer for Landsat-8 imagery by GeoSage is another free option for pan-sharpening Landsat 8 imagery. I have tried it and it works well if you don’t mind following some simple command line instructions. Check it out at this link.

Even more info: To get an idea of the best Landsat 8 band combinations and comparison with Landsat 7 bands check out this blog article from ESRI.

 
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MODIS through Google Earth Engine to monitor crops

What Google is doing with the earth’s satellite imagery is really quite amazing. Check out Google’s Earth Engine. On the landing page you get some great videos. I recommend Amazon Deforestation: Timelapse and Drying of the Aral Seas: Timelapse.

Once you have had enough of these visit their data catalog where you can load any of the common earth observing satellites into a Google Workspace which is the Google Map environment with additional features allowing you to display the satellite images.

Google say they have developed their Earth Engine mainly for monitoring deforestation which is valuable but there are several ways this technology is useful in agriculture. For example load the MODIS Daily EVI into the Workspace. Once in the workspace go to a farming area you know well and you can monitor how much (healthy) crop is established. Although MODIS imagery is free to download, Google take out all the processing time and make it easy to keep an eye on the district.

MODIS EVI captured on 2012-12-05. Showing area north of Moree NSW Australia. Google Earth Engine used to display image.
MODIS EVI captured on 2012-12-05. Showing area north of Moree NSW Australia. Google Earth Engine used to display image.

Flood water satellite image NW NSW & SW QLD

If you were wondering where the agmapsonline homepage image comes from – this is it. A  Landsat5 image captured on 23-03-2010. We have had two floods that have exceeded this flood level since.

Notice that the cotton paddocks remain completely protected. In fact you will find many cotton farmers still irrigating during large flood events. Other areas where the water spreads out is useful for filling moisture profiles and dropping valuable nutrients.

This is not a ‘true colour’ image. Of the three layered bands used to create the image I have only used one colour band and that is blue. The other bands used to produce the image are near infrared (NIR) and short wave infrared (SWIR). The SWIR, NIR and Blue bands are applied to the red and green and blue scales respectively to produce the image that you see.

This combination shows up healthy vegetation as bright green and water as blue (even though inland water is generally brown). Learn more about this here.

Click on image to view it full size.