SMALL-SCALE AERIAL SURVEY BEFORE THE PLANTING SEASON

A farmer in Makueni County, Kenya, sought to prepare her farm for the rainy season, so as to maximize use of her land. This was a good opportunity for us to  carry out a simple small-scale survey, and further prove the value that an aerial perspective brings to agriculture.

The idea was to provide the farmer with an up-to-date, high resolution aerial perspective of the farm land, a feat simply not possible using mainstream mapping services such as Google Maps, whose data is often a year old.

The project began by taking a few images at ground level, giving an eye-level perspective of the state of the farm. This can often prove crucial, as it gives context to the nadir (vertically overhead) imagery obtained later during the drone flight.

IMG_20180826_112535.jpg
Capturing reference images of the land pre-flight

Once this was done, we then proceeded to set up the UAV for the mission. This began with all necessary pre-flight checks, crucial for safety of both personnel and equipment. Propellers, motors, air frame, and flight battery voltage were just some of the parameters carefully studied to ensure a safe flight.

IMG_20180826_113013.jpg
Analyzing critical flight parameters at both the UAV and Control Station

With everything connected, what followed next was setting up the mission on the Ground Control Station (GCS), an Android phone with a special transceiver module attached, to have the UAV conduct a flight specific to our needs for the project. The flight parameters such as altitude, speed, image overlap percentage and flight path are all configured within Tower, the mobile application used for this project. Once uploaded to the UAV, the mission can then be started.

IMG_20180826_114841.jpg
Uploading the mission to the UAV

 

One other crucial component to set up before flight is the camera, which is installed right below the front of the UAV, and plugged in to a remote trigger, and GPS transmitter that allows the camera to geotag the images captured during flight.

IMG_20180826_113417.jpg
The multispectral imaging sensor used for this test

With the connection to the drone established, and the mission uploaded, we then set off to the first of many waypoints, all the while capturing aerial images of the farm land.

ascent_pics.jpg

 

We were able to begin our data analysis once we got back to base. The total number of images captured during the 7-minute flight was 179, with a total area coverage of just over 10 acres, at an altitude of 40 metres above ground level. The analysis software of choice is Pix4D, a leading aerial mapping solution covering a vast number of industrial applications.

QR_1
Brief summary on the quality report, showing ground sampling distance (GSD) and area covered
QR_2.jpg
Further data on the images analyzed and quality of data obtained.

The aerial images captured allowed us to have a greater understanding of the land in question, including a digital representation the general topography relative to the river Mwooni, a river known for bursting its banks during the rainy season.

Densified_point_Cloud_02
Digital representation of the images captured during flight, and the corresponding point cloud generated, from the perspective of River Mwooni

Densified_point Cloud_01

 

QR_3.png
Orthomosaic and Digital Surface Model (DSM), showing the relative slope of the farm land

The primary purpose of this preliminary UAV analysis was reconnaissance. With the data captured, a critical up-to-date reference point has been created, which can then be revisited once the planting begins. Further flights can also be conducted at various stages of the farming cycle to keep tabs on the health and general growth of the crops. Updates coming soon!

 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s