How to use TerrAvion's Standard and Dynamic Vigor Maps
The TerrAvion Standard and Dynamic Vigor maps allow users to both focus their NDVI images to bring out more detail and variability while also allowing them to see temporal changes in their fields throughout the season. While NDVI data remains constant for any particular image, altering the NDVI color-map for that image can change the way that data is illustrated in the image you see. Growers can use the Dynamic Vigor map to pull out more detail in a particular NDVI image, or use the Standard Vigor map (NDVI) to see temporal changes in their fields throughout the season and compare the growth vigor of multiple fields. Follow these directions below to learn about TerrAvion's Dynamic Vigor (Auto Adjusted) and how to manually adjust the Standard NDVI color-map.
Dynamic Vigor (Auto Adjusted)
The TerrAvion Dynamic Vigor layer is a normalized NDVI image. Normalization can make issues in your NDVI imagery more visible than in a regular, non-normalized image. The Dynamic Vigor layer automatically adjusts to focus on the growth vigor of a field on a particular day. It is important to note that the relative NDVI is not a good tool for comparing the results of different fields or comparing images of the same field taken on different days.
Standard NDVI Color-map (Manually Adjusted)
If you are looking for temporal changes in your field throughout the season or would like to compare one field to another, you should select the Standard Vigor layer. With the Standard Vigor image, you also have the ability to manually adjust it to bring out more detail and variability.
Note: As you alter your Vigor color-maps, please keep in mind that the actual data will remain constant. You are not altering the data, only the way that it is shown in your imagery.
2. To bring out the most detail, select the Dynamic Vigor layer from the map layers menu at the bottom of the screen.
3. OverView will always load the default NDVI color map for your Vigor imagery, but you can always elect to choose a different color-map. To do so, simply click on the color scale for your image in the bottom right-hand corner of your screen and select a map.
4. In the color-map menu window, sort by your favorite maps or click on ALL to see all vigor color-maps.
5. You can also choose to manually adjust your Standard Vigor map to bring out more detail. To do so, first select the Standard Vigor layer.
6. Click the Histogram button at the top of your screen to the right.
9. Note the range of NDVI values displayed on the x-axis of the histogram. The y-axis shows the amount of acres that currently are represented by a certain color of the NDVI image
10. Move the two adjustment points to either end of the range you noted in the previous step.
11. Note the change in the histogram. The goal is to see an increase in color representation on the histogram. If you do not see a noticeable color variation in on the histogram, readjust it.
12. Click Update map
13. If your map appears too green, too red or just generally isn’t displaying the detail and variation in the way you wish to see it, re-adjust the scale. Aim for a graph curve similar to the one shown below.
For more information on selecting a colormap, click here.