04 Apr

3 practical ways to use aerial images

Aerial drones capture amazing images. The aerial perspective and the image resolution provide a level of detail that is hard to beat. Much more than just pretty pictures, aerial images are a powerful tool for land management projects.

But using aerial drones to capture the image is just the start. Making good use of the image is where the rubber hits the road.

Here are three ways to use aerial images to really step-up your projects.


1. Smartphone orthomosaics

Take the high-resolution orthomosaic images captured by a drone with you into the field on your smartphone. Of course, the ability to take orthomosaics into the field has been with us for years, but now smartphones take it to a new level. With their computer power and smart apps, smartphones provide a very useful GIS tool. You can track where you are, mark waypoints, add notes from drop-down menus, attach photos, or draw polygons right onto your orthomosaic.

The orthomosaic becomes an interactive working tool. The accuracy is amazing.

phone shot

Screenshot of a smartphone using an orthomosaic in the field to record data about the site.

 

phone shot detail

Utilising the high resolution of an orthomosaic for detailed aerial views in the field.

 


2. Colour analysis weed search

High-resolution orthomosaic images have a lot of pixels. In a single 10mb photo taken with a 24MP camera there are 24 million pixels. An orthomosaic can be made up of thousands of photos – that’s a lot of pixels!

You can take advantage of all these pixels by employing an automatic search of pixel colour in the orthomosaic to look for weeds. We use this technique to focus our attention on areas more likely to have the weed. We sample the colours of the target weed, then search for pixels of those colours in the rest of the orthomosaic.

This method might not find the last weed present in your area, but it is a powerful visual aid to quickly focus your attention to weeds that your eye may not see in a visual grid search. It can significantly speed up the process of detecting and targeting weeds.

Colour analysis

An orthomosaic of a raupo-dominant wetland. The weed royal fern is difficult to visually detect amongst the other brown colours (scale 1:1,000)

 

Colour analysis detail

Sites suspected to be royal fern detected by a colour analysis of pixels (scale 1:500)

 

Colour analysis zoom

Close-up of a known royal fern, showing the distinctive reddy-brown colours. These pixels are sampled to use as a reference to search for other pixels of the same colour (pixel size=2cm).

 


3. Aerial photo-points

As ecologists, we often use photo-points on the ground to monitor changes in an area over time. Photo-points can also be done in the sky using GPS to record the exact position, altitude, and bearing of the drone for repeat images overviewing an area.

These aerial waypoints are delivered to the client so you can understand where each photo has been taken from. The photos can even be associated with the waypoints in your database so they can be viewed when clicking on the waypoint. When it is time to monitor the site again, we load the waypoints into the drone and send it back to the same spot in the sky!

Drone path and photopoints

3D flythrough showing drone path (yellow), photopoint locations and directions (red arrows) and example photopoint view (photo-point 4).

aerial point 4

Aerial photo-point 4 from the flight above. A wetland management area.

 


Call me (Hamish) on 07 394 4394 if you have any questions about this article, or if you’d like to discuss your project requirements.