Otago Central Railway [61W]: Alexandra-Cromwell 20

Last time I was talking about the challenge of aerial maps of the north part of Lake Dunstan. All of Lake Dunstan is of interest for historical purposes due to the hydro development resulting in indundation of a considerable area of land. Just as an aside I am about to do a map of Lake Karapiro which is an interesting one because it submerged the Horahora power station in the lake.
Anyway carrying on with Central Otago here is a sample of Clyde. The new Clyde mosaic is the second largest ever (north Lake Dunstan is the largest) that I have worked on. 8.9 GB and that is much increased from the previous version of Clyde which is only 1.9 GB. That’s essentially what it takes to do the maps at the higher resolution and quality with the LINZ tiles doubled in pixels in each direction therefore four times as many pixels overall, and in this case enough imagery to depict eight different periods: 1962, 1972, 1978, 1979, 1981, 1985, 1991 and 2014. As it happens there isn’t always aerial photography for the whole area for every single one of those periods so they can be made up of images from two slightly different periods.
So this image and others of the same series will be labelled “1962” but in fact the 1962 stuff I have only covers the main part of the first Clyde station. The part coming down into the 2nd station site is actually lower resolution stuff from 1958, but the 1962 survey isn’t fully online yet, only the parts I previously paid to have scanned from Archives New Zealand are useful to me.
Another mishmash example is 1972 which is the NZR surveys of the 1st Clyde station combined with some 1977 stuff.I have however checked what I can get from 1974 and 1976 and am reasonably confident that this so-called “1972” stuff is reasonably close to what was actually there in 1972 across the 2nd site. There wasn’t enough difference between 1972 and 1977 across the 1st Clyde station to justify a different era of imagery for that site.

Anyway all the tiles have been made and imported into the maps ready to go.