# THE MAPPING OF HONG KONG
137
Following completion of each block of four sheets at the 1/10,000 scale, one sheet at 1/25,000 scale, covering the same area, will be produced by direct photographic reduction. An extra colour, green, is introduced in the 1/25,000 series. The place-names are printed separately for each series. As a result of the 24 times reduction, the size of each sheet at the 1/25,000 scale is smaller (map face 20″×17″) and 20 sheets will cover the whole Colony. The diagram at Plate 14 shows the relationship between the two series.
Once again, the ground-control for the photogrammetric plotting was supplied by Survey Branch. Of course, many fewer points were required, since fewer stereoscopic "models" were required at the smaller scale than at the large scale. The low-level photography of January 1963 required over 4,000 air photographs to give stereoscopic cover of the Colony, whereas at 12,500 ft., only 346 photographs cover the same area.
An "instrument plot" of each 1/10,000 sheet is sent to Hong Kong for field completion by Survey Branch. On this, the field parties check and complete all detail, and annotate roads, villages, towns, etc. The completed and annotated sheet is then returned to Britain, together with a names overlay and names list, for fair drawing and printing.
At the end of 1968, some 18 sheets had been published and another 26 had been plotted, field-checked, and were at the fair-drawing stage. The first sheet at the 1/25,000 scale had been drawn, and a coloured proof has been forwarded to Hong Kong for comments. The first 12 sheets of the 1/10,000 series are already on sale at Kelly & Walsh Ltd. and Swindon Book Co., Ltd.
It is expected that the 1/10,000 series will be completed by early 1971 and the 1/25,000 series by the end of that year. It is hoped to produce future revised editions of the maps in Hong Kong. Revision of the first sheets to be published will be commenced early in 1969.
It is also planned to produce locally a Chinese-language edition of the new maps, although full details are not yet finalised, and much will depend on the availability of specialised printing equipment.
An old series of maps which is still quite popular is the 8″ to 1 mile set of the urban areas. These are revised annually and
THE MAPPING OF HONG KONG
137
Following completion of each block of four sheets at the 1/10,000 scale, one sheet at 1/25,000 scale, covering the same arca, will be produced by direct photographic reduction. An extra colour, green, is introduced in the 1/25,000 series. The place- names are printed separately for each series. As a result of the 24 times reduction the size of each sheet at the 1/25,000 scale is smaller (map face 20′′×17′′) and 20 sheets will cover the whole Colony. The diagram at Plate 14 shows the relationship between the two series.
Once again the ground-control for the photogrammetric plotting was supplied by Survey Branch. Of course many fewer points were required, since fewer stereoscopic "models" were required at the smaller scale than at the large scale. The low-level photo- graphy of January 1963 required over 4,000 air photographs to give stereoscopic cover of the Colony, whereas at 12,500 ft. only 346 photographs cover the same area.
An "instrument plot" of each 1/10,000 sheet is sent to Hong Kong for field completion by Survey Branch. On this the field parties check and complete all detail, and annotate roads, villages, towns etc. The completed and annotated sheet is then returned to Britain, together with a names overlay and names list, for fair drawing and printing.
At the end of 1968 some 18 sheets had been published and another 26 had been plotted, field-checked and were at the fair- drawing stage. The first sheet at the 1/25,000 scale had been drawn and a coloured proof has been forwarded to Hong Kong for comments. The first 12 sheets of the 1/10,000 series are already on sale at Kelly & Walsh Ltd. and Swindon Book Co., Ltd.
It is expected that the 1/10,000 series will be completed by early 1971 and the 1/25,000 series by the end of that year. It is hoped to produce future revised editions of the maps in Hong Kong. Revision of the first sheets to be published will be com- menced early in 1969.
It is also planned to produce locally a Chinese-language edition of the new maps, although full details are not yet finalised and much will depend on the availability of specialised printing equip. ment.
An old series of maps which is still quite popular is the 8" to 1 mile set of the urban areas. These are revised annually and
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