What NDVI Drone Scanning Actually Shows a South Texas Farmer

RGV DroneVista • June 2025

If you farm in the Rio Grande Valley, you have probably heard the word NDVI. Maybe from an agronomist, maybe from a seed rep, maybe from an ad. But there is a big difference between knowing the acronym and understanding what a map of your own field actually tells you.

This article explains what NDVI is, what the data looks like when we scan a South Texas field, and what farmers actually do with it.

What NDVI measures

NDVI stands for Normalized Difference Vegetation Index. Plants reflect light differently depending on how healthy they are. A healthy plant absorbs most visible red light and reflects a lot of near-infrared light. A stressed, dry, or diseased plant does the opposite. It reflects more red and less near-infrared.

A standard camera cannot see this difference. Our drone carries a multispectral sensor that captures both visible light and near-infrared at the same time. The NDVI calculation compares those two values for every pixel in the image. The result is a number between negative one and positive one for each spot in your field.

We then color-code those numbers into a map. The colors you typically see:

• Dark green: dense, healthy vegetation
• Light green or yellow-green: moderate stress or thinner canopy
• Yellow or orange: significant stress, drought, or disease pressure
• Red or bare: very low vegetation, crop failure, or exposed soil

What a real South Texas field scan looks like

In the RGV, we scan a lot of dryland sorghum, irrigated cotton, and native pasture. The pattern that shows up most often in dry years is rainfall variability. A field that looks uniform from the road will show on the NDVI map that the east side got a good shower last month and the west side did not. You can see exactly where the soil moisture ran out.

On irrigated fields, the most common finding is clogged or broken emitters. One pressure problem mid-season can stress a 50-foot strip of cotton before anyone notices it from the ground. On the NDVI map, that strip lights up yellow or orange while the rest of the field is green. You know exactly where to check.

Pasture scans show where grass is burning out under heavy stocking. Instead of moving cattle based on guesswork, you can see which paddocks have dropped below a usable threshold and which still have weeks left.

What you get from us

After a flight, we process the imagery and deliver three things within 48 hours:

• A color NDVI map as a georeferenced image you can view on any device
• A shapefile you can load into any precision ag platform
• A PDF report with annotated zones and notes on what the data shows

The PDF report is useful beyond just looking at your field. If you are filing a crop insurance claim, your adjuster needs third-party documentation. A report from an FAA Part 107 licensed operator using a calibrated multispectral sensor carries weight in that conversation in a way that your own photos do not.

When to fly

Multispectral scans require natural sunlight and clear skies. In South Texas, the best windows are early morning through mid-morning before heat haze builds, and late afternoon. We fly around your schedule and the forecast.

The most useful time to scan is when stress is developing but not yet visible to the eye. By the time a field looks bad from the road, you have already lost weeks. NDVI shows stress two to three weeks earlier than visible browning, which is the window where you can still make a difference.