2 posts tagged with "Retrolens"

Downloading a historical aerial photograph is only the first step. To compare it meaningfully with current information, the scan often needs to be connected back to place. That sounds like a technical problem, but georeferencing is also an act of interpretation. We are taking an image captured at one time, often for a survey purpose, and relating it to a present-day coordinate system and landscape that may have changed substantially since the photograph was taken.

For Māori GIS that distinction matters. The goal is not to make an old photograph submit neatly to the modern map. Awa may have moved, coastlines may have changed, roads may have been built and landforms altered. A photograph can help reconnect records and memories to whenua, but its position, its meaning and the conclusions drawn from it still need to be checked against other evidence and, where relevant, the people who know the place.

This older workflow used Google Earth Pro's Image Overlay tool to align an image visually. It can still be useful for people who already have Google Earth Pro installed, but it should now be treated as a legacy exploratory method, not the recommended way to build a new repeatable workflow.

One of the most useful tools for understanding physical change in whenua over time is historical aerial photography. In Aotearoa, the easiest public way to explore much of this imagery is through Retrolens. The photographs can show rivers before they were straightened, wetlands before drainage, roads before widening, forests before clearance or planting, coastlines before reclamation and settlements before later development.

For Māori GIS, however, the value of historical imagery is not that an aerial photograph somehow reveals the complete truth of a place. It is one view, captured from above at a particular moment for a particular survey purpose. It can sit alongside kōrero tuku iho, whānau memory, historical records, maps and knowledge held by people connected to the whenua. Sometimes a photograph confirms something remembered locally. Sometimes it raises a new question. Sometimes it shows physical change without explaining why that change happened or what it meant to the people living there.

Retrolens provides access to scanned aerial photos dating from the mid-1930s through to the late 1980s. This period covers enormous change in land use, drainage, forestry, farming, road construction, river modification and urban expansion. Used carefully, these images can help reconnect documentary records and present-day geography with landscapes that have since been altered.