AERIAL PHOTOGRAPHY

Hawke's Bay Herald-Tribune, Issue 155, 19 July 1937, Page 8

AERIAL PHOTOGRAPHY

Immense Possibilities of Work . / MAPPING SURVEYS A most 'interesting talk on aerial photogra-phy was recently given to members of the Heretaunga Tramping Olub at Hastings by Mr Piet van Asch, of the New Zealand Aerial Mapping Co., Ltd. This is the first talk of its kind given in New Zealand and showed the immense possibilities of this type of work. Photographs and lantern slides 'were used to illustrate the various uses to which such pliotograpliy could be put, such as searching for oil in .Persia, doing liousing surveys in crowded portions of England, surveying estates, obtaining progress reports on large contracting jobs, and doing ordinance survey work, Probably the most interesting pliotograph was that showing the ground plan of an old Roman dweLing. Tho remains of this dwelling were entirely covered by six feet of soil, on which was growing a field of ripe oats. Owing to the variation in colour of the .oats it is possible by taking a vertical photograpt from the air to obtain a perfect representation' of the buried building. In addition, there were many fine views of London both oblique and vertical, and these are probably the best and most comprehensive collection in New Zealand. The possibilities of tbe work are immense. Mr van Asch has already done mapping work in the Glenorchy district, and this will be continued when weather conditions are favourable. The method of mapping is to fly over the country at a fixed altitude and then to parellel the course and to overlay the photographs. This overlapping enables stereoscopic photos to be constructed to show tbe contours of tiie country, The camera automatically records on each negative the altitude, exact tifiie, the date and the serial number, so that any rectification of the negative t can be carrled out in the Maboratory. Neediess to say, the detailed mside work takes much greater time than the actital flying, which is done at 100 miles an hour, -and the great companies operating in England employ large nuinbers of draughtsmen, although the hours available for llyin'g are very llmited. " Mr van Asch has brought back to New Zealand a special Monospar aeroplane which is constructed so as to give the gregtest sfcability in llyiug . and to allow the pilot as wide an agle of visibili^y as possible. It will be" remembered that aerial mapping was earried out in the flight over Mr Everest.