Aerial Drone Weed detector

[farmerfred]

Hi,

So I recently (and very gratefully) received help here to set my raspberry pi camera to take images with our aerial drone for crop health monitoring...

We're now moving the project onwards and I'm looking for help... We need some hardware/software capable of determining large weeds amongst our crops...

Eventually I want the drone to take action and fly over to the weed... but has anyone got any comments on using software to detect these weeds? Because they stand out well above the regular crops they are usually easy to identify by eye?

[Jessie]

Sorry I'm not getting a picture. Usually, for drug inforcement they use ir and polarized cameras to look for something that resembles their target. I imagine you could do the same to target your particular weed.

[DougieLawson]

I think it's not "weed" as in "dope", but "weeds" as in "unwanted plants".
The worst weed they grow here is that horrible, yellow, stinky oil seed rape. Dope gets grown indoors using stolen electricity to power the lights needed to keep the crop warm.

It looks like it needs two cameras, one in the visible spectrum, one in the IR spectrum and some complex maths to detect the plants that aren't part of the desired crops.

[BMS Doug]

And some kind of accurate location detection to identify where the weeds are.

Ragwort is a fairly common, persistent weed in the uk. As it's poisonous to cattle it's actually mandatory to control it (although many people don't realise it and it often grows in the verges on the side of the roads).

[DougieLawson]

And some kind of accurate location detection to identify where the weeds are.

I assumed an aerial drone would already have a GPS receiver.

[BMS Doug]

I assumed an aerial drone would already have a GPS receiver.

Good assumption, I should probably get some sleep instead of staying up all night on the forums.

[aTao]

Ragwort is a fairly common, persistent weed in the uk. As it's poisonous to cattle it's actually mandatory to control it (although many people don't realise it and it often grows in the verges on the side of the roads).

Only when it is within 50 metres of your boundary. Ragwort causes cumulative liver damage only when consumed, it can also cause skin irritation that cannot cause poisoning but most people get the heebe-geebies at the rash.

However this isnt much to do with drones....
One big mistake when trying to recognise plants is to use human eyesight, its pathetic, what you want is the eyesight of a grazing animal, thy have incredible green vision and can seethe different plants, even growth stages of plants from great distances. You might find that the RPi camera can also out-perform human vision.

[jbeale]

Code: Select all

...Because they stand out well above the regular crops they are usually easy to identify by eye?

Sounds like this particular problem is simpler than the general case. If the undesired plant is much taller than the surroundings, it should not take sophisticated color algorithms to spot it. Instead it will take sophisticated geometry-extraction algorithms... actually, if the bad plant stands out at some color (wavelength), then a matched selective filter on a camera could be the best approach.

The R-Pi actually can do some pretty powerful image processing, and libraries such as OpenCV have many algorithms available (unfortunately, generally not on the R-Pi's GPU image processor, but they can still work.)

[Burngate]

Because they stand out well above the regular crops they are usually easy to identify by eye?

Spot the weed

screen1a.png (57.19 KiB) Viewed 2955 times

I'm guessing the drone will have to fly fairly low to see the weed above the crop, and have a neutral background?

[ame]

And some kind of accurate location detection to identify where the weeds are.

I assumed an aerial drone would already have a GPS receiver.

You'd think so, but we've had this discussion before. Maybe this time there is a compelling reason to install one.

[farmerfred]

Yes the drone has 2 GPS sensors installed.

You make a good point about the height... Only by flying low will the weeds stand high above the crops. That could pose a problem.

[ame]

Yes the drone has 2 GPS sensors installed.

You make a good point about the height... Only by flying low will the weeds stand high above the crops. That could pose a problem.

Just curious, why two GPS sensors? That's extra weight and power consumption.

Anyway, can you fly the drone at night? If the weeds are taller than other plants could you shine a light and look at the shadows? If you cast a light at a low angle it makes the shadows much larger, so easier to see.

[jbeale]

Anyway, can you fly the drone at night? If the weeds are taller than other plants could you shine a light and look at the shadows? If you cast a light at a low angle it makes the shadows much larger, so easier to see.

That's a good idea. Of course if your light is right next to the camera, you won't see the shadows, being always hidden behind whatever casts them. But if you have either the light or the camera mounted on a pole so there is some distance, and thus angle difference between light source and camera, then you should be able to see the shadow that the weed plant casts over the crop. Depending on the texture of the crop's top surface leaves, though, I'm still not sure if fully automatic recognition is necessarily easy.

In general this is a 3D extraction problem, you want to know the shape of the surroundings in 3-D, so you can pick out the tall objects. I know there have been demonstrations of algorithms that combine several still images from different angles to create a 3D model of a scene. Whether that could run in real-time on a Pi, I don't know. Maybe with very limited resolution, it could work.

And of course, if it all does work, don't stand in the field yourself during this process or you might get doused with herbicide, I guess! And if it does work and you selectively eliminate all the tall weeds, that means short weeds will now proliferate, but I guess that's another story.