Aerial Normalized Vegetation Index

why

As a farmer you want to know how your crops are doing. Are they gronwing good, need more water ect.
Color pictures can be used ofr NDVI pictures.
NDVI (Normalized Difference Vegetation Index)
The easy way to accomplish this is trough aerial pictures. And the cheap way is with a drone.
Type:

  • Quadcopter
  • Helicopter
  • Plane

Quadcopter

A quadcopter is easy to use (after calibration) and easy to build. Can fly mazimum 30-45 minutes on one charge.
It cannot cover allot of ground as a helicopter or plane. I choose a quadcopter.

Helicopter

Helicopter is more difficult to fly and complex to build. Can cover allot of ground.

Plane

A plane is easy to build but difficult to use. It can cover allot of ground. A plane is more efficienbt than a heli/quad copter.

Drone v2

To make color pictures and NDVI picutres the drone must carry 2 cameras. So I made my own drone.
The goals is to fly atleast 20-25 minutes.

Drone_v2_1

Done_v2_2

Safety

Using a drone you need to use common sens. Here are some rules/points that I do.

  • Always check you drone before flying
  • Know your air space before you fly, how close are you to airports, low flying areas ect. For holland
    check AIS-Netherlands
    Most people do not do this but it is important to know your loacal arways for safe flying.
  • Know your drone, how does it handle in calm and rough wheater. How long can it fly. How does it fly
    with low battery
  • Have backup plan when problems occur, for exnaple: Know what to do when low battery occurs
  • Use all the safety feature of your drone controller, my case:
    • Lost rc signal: return to home
    • Lost basestation signal: return to home
    • Low battery: land at designated points
    • Lost GPS signal for 5 seconds: Land
  • Do not fly over people, in my case carbon props will cut you very badly if you incounter my
    drone. Becuase of a building mistake my first drone crash after 5 minutes flight, so it can happen
  • Respect people privacy
  • Use common sense, know your limits and enjoy

NDVI

For NDVI I use two consumer cameras. On camera is not modified. The other camera I remove the IR filter and place a new 720nm filter. For most of the picutres the dones is flying 80m. Because in holland there are allot of recreational flying activities I keep it at 80 meter for safety.
NDVI pictures have a scale form -1 .. 1 Water rocks are around -1 -0.5. Healty plants 0.2 .. 1.
This puctures give you an indication of how good your crop is doing. Also you expect an even color over your crops. ID the colors differ than you know something is wrong. Plants will show sign of stress in NDVI pictures before you see it in color pictures. Below the scale.
NDVIBlu2Redt
The best time to take pictures is arroud noon. Some of the pictures below where taken on the end of the day. This cuase the NDVI picture to be more on the right of the scale. This has to do with sun light reflection.
Also my pictures are not correct for lens barrel distortion. Still need to be done.

Corn/Grass field and Sugar beet

Corn/Grass field gallery

Grass for cattle

This picture is of grass which is used for cattle feed. On the left of the stream the grass is growing. On the right the grass was cut a day before the picture was made. The pictures are a bit high on the NDVI scale be cuase the pictures where taken in the end of the day when the sun was low.

CRW_0447CRW_0447_NDVI_Color

Corn field

A part of a corn field. Notice that the corn close too the stream are not that well as the rest of the field.
On the color picture you can see that close by the stream the density of the corn is not that high. But 10 meter inward it looks like the corn are doing well. But on the NDVI image you can see that they do less than the corn more inward. Also notice a patch on the right of the picture where the corn also are doing less.

CRW_0453

CRW_0453_NDVI_Color

Sugar beet

These pictures of a suger beet field. Was taken very late that day. But still good NDVI result.
CRW_0463CRW_0463_NDVI_Color

Patato field arround eindhoven

This is one of the field that is good to know the air space arroundthe flied.
There is a civilian airport 8 kilometer away. I was under the landing route of the planes that day. But they never fly lower than 914 meters. So my 80 meters is safe.
Patato field gallery

CRW_0489

CRW_0489_NDVI_Color

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