The second thing we can do is take models of plants, construct three-dimensional reconstructions, and from that estimate the canopy size, and then correlate the canopy size to the amount of leaf area on every plant. And this is called the leaf area index. So if you know this leaf area index, you essentially have a measure of how much photosynthesis is possible in every plant, which again tells you how healthy each plant is. By combining visual and infrared information, we can also compute indices such as NDVI. And in this particular case, you can essentially see there are some crops that are not doing as well as other crops. This is easily discernible from imagery, not just visual imagery but combining both visual imagery and infrared imagery.