Satellite’s eye in the sky gives councils oversight


Alexandra’s Xerra Earth Observation Institute is partnering with Auckland Council on a system for urban change detection.

Xerra chief executive Steve Cotter said using satellite imagery and machine­learning they could automatically detect new building sites from space.
New Zealand had a high volume of residential building activity and it was hard for councils to know when construction had started, and to visit every site, Mr Cotter said.

By applying ‘‘machine­ learning algorithms’’ the system could detect when there was a significant change in vegetation on a site, ‘‘e.g. a site had vegetation in October, and now has none’’.

This was able to be linked to databases showing individual addresses, allowing the council to conduct its own checks to ensure sites were compliant and had relevant building consents.

Helping council staff visit and assess sites early in their construction phase allowed them to check for and mitigate issues such as sediment and stormwater run-off, changes to land stability and visual impacts on landscapes, Mr Cotter said.

Other uses of the system included looking under the surface of lakes to detect toxic algal blooms ‘‘from space’’.

‘‘We can notify them when the toxic algae is there so they can tell people not to go swimming — things like that.’’

The system was also capable of identifying more than 20 different types of crops — ‘‘you can tell if a field is planted with potatoes or winter wheat or sugar beet or corn’’, Mr Cotter said.

‘‘You can actually measure everything, how many acres are planted, stuff like that.’’

After working with Auckland Council on the project over the past few months, Xerra presented the concept at the Environmental Compliance Conference in Christchurch recently.

It was now gauging interest from other councils including Central Otago District Council and Queenstown Lakes District Council, Mr Cotter said.

Satellite scanner … Xerra chief executive Steve Cotter shows an example of their urban change detection system. PHOTO: SIMON HENDERSON