The TerrAvion Standard and Dynamic NDVI 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 NDVI map to pull out more detail in a particular NDVI image, or use the Standard NDVI map (Vigor) 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 Relative NDVI map (Auto Adjusted) and how to manually adjust the Standard NDVI color-map.
Dynamic NDVI Layer (Auto Adjusted)
The TerrAvion Dynamic NDVI layer is a normalized NDVI image. Normalization can make issues in your NDVI imagery more visible than in a regular, non-normalized image. The Relative NDVI layer automatically adjusts to focus on the growth vigor of a field on a particular day. It is important to not 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 can simply select the Standard NDVI "Vigor" layer. With the Standard NDVI layer, you also have the ability to manually adjust it to bring out even more detail and variability in their NDVI imagery.
Note: As you alter your NDVI color-maps, please keep in mind that the data will remain constant. You are not altering the data, only the way that it is illustrated in your imagery.
3. To see more detail in your NDVI imagery, select the Dynamic Vigor layer from the map layers menu at the bottom of the screen.
5. OverView will always load the default NDVI 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.
6. In the color-map menu window, sort by your favorite maps or click on ALL to see all vigor color-maps.
7. You can also chose to manually adjust your NDVI map. To do so, first select the Vigor map layer for your image.
8. 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.
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 more color representation on the histogram. If you do not see noticeable color variation 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, readjust the scale. Aim for a graph curve similar to the one shown below.
Please contact firstname.lastname@example.org for any additional questions on how to adjust your NDVI color-map.
Click here to learn how to use TerrAvion's adjustable thermal color-map.