Historic high-resolution imagery boost for ETS

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High-resolution aerial photos of rural New Zealand from around 1990 are now publicly available for use in mapping and spatial analysis. They will be used for a broad range of applications by government, councils, forestry consultants, businesses, universities and the public.

Te Uru Rākau – New Zealand Forest Service (TUR-NZFS) and Toitū Te Whenua – Land Information New Zealand (LINZ) have partnered to process and release more than 38,000 high-resolution aerial images captured between 1975 and 2005, with most of the images taken around 1990.

The imagery was scanned by Toitū Te Whenua through the Crown Aerial Film Archive historical imagery scanning project. TUR-NZFS then improved the imagery’s immediate usefulness for mapping and spatial analysis by orthorectifying (spatially aligning to real-world locations and removing distortions) and mosaicking (stitching together).

TUR-NZFS made a significant investment to process and release this imagery, which covers about 70 million hectares. This has resulted in most of the country now having access to mapping and analysis-ready, high-resolution imagery either side of 1990 that was previously unavailable to the public.

The primary driver for processing and releasing this imagery was to provide high-quality data to inform Emissions Trading Scheme (ETS) forest land status. The ETS incorporates 31/12/1989 as a key date to determine forest land entitlements and obligations and aerial imagery is the most definitive and comprehensive information source to inform ETS land status at this date. As information confirming the date of forest establishment so long ago is often patchy, the availability of historic high-resolution imagery is of great assistance for more accurately verifying forest establishment dates, determining forest extent and ETS status.

The processing and public release of this imagery will produce benefits for the ETS, including:

• Increasing the integrity of the forestry aspects of the ETS

• Helping ETS forestry applicants and consultants to prepare applications and increasing the accuracy and certainty of their self-assessed land status

• Providing investors greater certainty for their land use investment decisions due to increased certainty of ETS land status

• Reducing the effort of ETS assessments by Te Uru Rākau – New Zealand Forest Service and increasing the accuracy and transparency of these assessments.

The release of this imagery addresses a key information gap for the ETS says Phillip Lubeck, Manager of Spatial Intelligence at TUR-NZFS.

“Prior to this project, orthorectified near 1990 imagery coverage was patchy, lower resolution and not publicly available. The release of this mapping and analysis ready imagery is a major step change for ETS forest land status decisions. We also recognise there are broader uses of this imagery that organisations and the public will benefit from, such as analysing and modelling other types of land use and environmental change,” Phillip Lubeck says.

Below is an example comparison of the previous low-resolution imagery (left) and the new version high resolution version (right).

Spot spraying associated with recent forest planting is visible on the newly processed imagery, enabling increased confidence and accuracy of land management practices and ETS forest land status.

The imagery is hosted on https://basemaps.linz.govt.nz/ using Toitū Te Whenua’s Amazon Web Services (AWS) Registry of Open Data. As the lead agency for administering aerial imagery and custodians of the Crown Aerial Film Library, hosting by Toitū Te Whenua is a natural fit. Additionally, the public release of this imagery coincides with other high-resolution imagery made available on LINZ Basemaps.

While the primary purpose was to support the ETS, we anticipate the imagery will be used for a broad range of applications by government, councils, businesses, universities and the public. Making the imagery publicly available and consumable for GIS applications were requirements for this project, so we are thankful for Toitū Te Whenua’s efforts to make this a reality.

We will look to process and publish more historic imagery on LINZ Basemaps in future.

Source: Te Uru Rākau – New Zealand Forest Service

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