Using Retrolens to explore historical aerial imagery in Aotearoa
One of the most useful tools for understanding change in whenua over time is historical aerial photography. In Aotearoa, the easiest public way to explore this imagery is through the Retrolens website.
Retrolens provides access to scanned aerial photos dating from the mid 1930s through to the late 1980s. For Māori GIS work, this period covers major changes in land use, drainage, forestry, farming, road construction, river modification, and urban expansion. It is often the clearest visual record of what existed before modern planning and regulation.
What Retrolens is
Retrolens is a public viewer for historical aerial imagery held by Toitū Te Whenua Land Information New Zealand. It allows you to browse, preview, and download scanned aerial photographs that were captured during government and private survey flights.
The site is here:
The imagery itself comes from the LINZ historical aerial photo collection:
Retrolens does not show everything as a seamless map. Instead, it shows individual photo frames, exactly as they were captured during survey flights.
Why this imagery matters for Māori GIS
For many Māori land blocks, the most significant changes happened before the 1990s. Retrolens imagery can show:
- original stream alignments before straightening or diversion
- wetlands that were later drained
- pā sites, terraces, and garden features before modification
- early forestry planting boundaries
- historic access tracks and roads
- coastline shape before reclamation or erosion
These photos often match kōrero tuku iho and whānau memory more closely than modern imagery.
Navigating the Retrolens site
When you open Retrolens, you will see a modern basemap with coloured footprints overlaid. Each footprint represents a single aerial photo.
Key things to understand:
- Each photo is a single frame, not a stitched mosaic
- Photos overlap slightly with each other
- Different years and flight runs may overlap the same area
You can:
- zoom to an area of interest
- click a footprint to see photo details
- preview the scanned image
- download the scan as a JPEG or TIFF
The metadata panel is important. It includes:
- flight name or number
- year of capture
- approximate scale
- frame number
Always record this metadata if you plan to use the image later.
Understanding dates and coverage
Retrolens imagery ranges roughly from 1936 through to the late 1980s. Coverage is uneven.
What you will commonly see:
- good coverage of rural areas used for farming
- dense coverage near towns and transport corridors
- gaps in remote or rugged areas
- multiple years for some locations, only one for others
Do not assume that a single year tells the whole story. Often the most insight comes from comparing two or three different years.
Image quality and limitations
These images are scanned photographs. They are not orthorectified and they are not perfectly aligned to modern maps.
Common characteristics:
- black and white imagery
- film grain and scanning artefacts
- distortion near edges
- shadows hiding detail in steep terrain
This does not reduce their value. It just means they should be used carefully.
Downloading imagery for further use
Retrolens allows direct download of scans. These files are not georeferenced. They are simply images.
Before downloading, decide:
- which frames you actually need
- which year best suits your kaupapa
- whether one image is enough or you need a small set
Downloading fewer, well chosen images makes later work easier.
Using Retrolens alongside modern basemaps
A good approach is to view Retrolens in one browser tab and LINZ Basemaps in another:
This helps you visually compare:
- historical features versus current state
- alignment issues caused by terrain
- features that no longer exist
Retrolens is for discovery and interpretation. GIS comes later.
Retrolens and tikanga
Historical imagery can reveal sensitive sites. Just because an image is public does not mean it should be widely shared.
Before publishing or distributing:
- consider who the audience is
- consider what the imagery reveals
- consider whether clipping or generalising is appropriate
Retrolens is a powerful taonga. Use it with care.
Final thoughts
Retrolens is one of the best starting points for historical whenua analysis in Aotearoa. It is simple to use, publicly accessible, and grounded in authoritative archives.
For Māori GIS work, it often provides the missing visual context that modern imagery cannot. The key is to treat it as evidence, not truth, and to carry its limitations forward into any later mapping work.