Access aerial imagery, captured on 24 February 2011, of the area affected by the earthquake that struck Christchurch on 22 February 2011.
The imagery has been released by Land Information New Zealand on behalf of the Crown, on the authority of the Civil Defence National Controller.
This dataset was produced by New Zealand Aerial Mapping Limited (NZAM) at the request of the Christchurch Response Centre to support the response to the earthquake.
The geodata is all in terms of the New Zealand Transverse Mercator 2000 map projection.
Copyright & licensing
This imagery is licensed under a Creative Commons Attribution 4.0 International licence with Crown copyright reserved.
This means anyone is free to copy, distribute, and adapt the imagery so long as it is attributed to the Crown, eg "Crown Copyright Reserved."
Access the imagery
Imagery is available for free download through the LINZ Data Service
In order to expedite their production, these orthophotos were produced using a number of shortcuts that would not be followed for a fully specified orthophoto project.
The aerial photos position and orientation (POS) were determined using the POS observations collected at the GPS base station and in the aircraft. This data was processed using the New Zealand Geodetic Dataum 2000 (NZGD2000) reference system. A coordinate for the base station was computed using single baseline processing and data supplied by to NZAM by GNS Science, from the PositioNZ station MQZG. Given the magnitude of the earthquake it is likely that the location of MQZG has changed. However, as no information was available at the time the photos were ortho-rectified (made into a photo map), it was assumed that the coordinate for MQZG had not changed.
For the orthophoto generation NZAM used a Digital Terrain Model (DTM) sourced from within its archive. This DTM was not edited or checked for change.
Automated mosaic seam line placement was used during the orthophoto production. NZAM chose to use a simple 'most nadir' algorithm for their placement. This selects the most central portion of each available photo and thereby helps minimise the amount of perspective view lean on buildings. The seam lines can be clearly seen on some of the photography.
Given the emergency, the orthophotos have only had a cursory review. Given that the DTM was not updated and checked it is likely that the orthophotos will include areas were the imagery appears smeared or is out of position.
While NZAM endeavoured to collect cloud free photography there is the odd puff of cloud and cloud shadow in the imagery. This does not significantly impact on the usability of the photography for the earthquake response work.