Five years of rebuilding Christchurch, as seen from the sky

Two days after an earthquake levelled central Christchurch, the disaster was documented from the sky.

Five years on, updated aerial imagery taken earlier this year gives a stark view of the rebuild and how the city has transformed.

Drag the sliders to see how the city has — or in some cases, hasn't — changed since the chaotic hours in the aftermath of the quake.



BEXLEY AND THE RED ZONE



Bexley in the city's east was once home to more than 4000 people, before it was decimated by the earthquakes. New maps show just eight homes remain.



Two days after the quake, Brook St was inundated with liquefaction. Two homes are still there.

Nearby, you can see another, even more isolated house in Bexley.

Many of the area's roads are closed, except for the ones leading to houses.

The before photo shows a well-populated area that is now gone.

Take it back further, and you can see the extent of the change in the red-zone.

Homes near the Avon River were particularly affected, hundreds of them demolished.

There are no plans in place to use the empty land.

Porritt Park was badly hit by the earthquakes, as were the houses surrounding it.

The hockey turf has been dug up, and the imprint remains.

A couple more houses have stayed opposite.

THE CENTRAL CITY

From ground level, walking the city can be disorienting. New buildings appear every day.

The cathedral, however, is stubbornly the same. In the before image, you can see entire blocks were demolished. To the right are tents in Latimer Square, used as a hub for post-quake emergency work.

The CTV building on the corner of Cashel and Madras streets, seen to the right of the below slider, collapsed on February 22, killing 115 people.

There is now a small, temporary memorial on the site, which is layered with white stones.

Like much of the city, it is surrounded by broad, open car parks. To the right of the after image is the Transitional Cathedral.

Further north are the remains of another major disaster on February 22, the collapse of PGC House.

In the before image, the collapsed building is just north of the river in the centre of the image. It is now an empty space. 18 people were killed.

At the bottom of the after image are the remains of an office tower now filled with water, like a small, urban lake.

One of the worst affected areas was High St, running diagonally across the image.

In the before image, you can see where buildings collapsed onto Manchester St.

Progress has been slow — part of High St is still closed, and car parks remain along Lichfield St.

In the city's south, the former AMI stadium continues to be an unfortunate landmark.

It has continued to deteriorate, while a scattering of new buildings have risen around it.

The north stand has been demolished, but that's about it.

One of the more striking new developments was Hagley Oval.

To the right is Christchurch Hospital, which you can see is expanding in the after image.

The images also show more buildings that made way for car parks.

Another new development is the bus interchange on Tuam St, seen in the top left of the after image.

It replaced retail buildings that were demolished.

Other buildings have sprung up too.

"WE WERE HAVING TO TAKE OUT RESIDENTIAL AREAS"

For the government's cartographers, the rapid change has presented a unique challenge.

How do you map areas that no longer exist?

Land Information New Zealand (Linz) uses the detailed aerial imagery to create topographic maps, used by search and rescue operations.

They go into striking detail, marking individual buildings and even trees in some areas.

Cartographers will soon release new maps of Christchurch based on the latest imagery.

LINZ/SUPPLIED The Avon Loop in 2010 and 2014. Grey shade represents a residential area. Roads filled with orange are open, roads filled with white are closed.

"This is a unique situation which had never happened before in New Zealand," said cartographer Graeme Jupp.

"We're quite used to adding in new roads and residential areas in cities, but in this case, we were having to take out residential areas."

It can clearly be seen in Bexley, once a suburb of 4000 people, now home to just eight houses.

LINZ/SUPPLIED Bexley in 2014 and 2016. Each black box represents a building. There are now eight homes in the suburb.

Similarly hundreds of homes were uplifted near Burwood, soon to be removed permanently from the government's maps.

"We had to carefully consider — these areas have changed, how are we going to show that change knowing full well there will be more change in the future."

Where roads were typically marked with black lines in-filled with orange, closed roads are now just white.

Grey blocks signifying residential areas are now black boxes marking individual houses.

"It's not the sort of thing we'd like to do all the time. But we had to do it, as we can't simply leave things as they were.

"To think this event quickly changed the lives of these people is terrible. When you see it on an aerial photograph it brings it home."