Report of the Department of Lands and Forests for fiscal year ending March 31, 1951 Page 134 



AERIAL SURVEYS SECTION 



The process of "unsharp masking" has been developed in co-operation with 

 the University of Toronto and the Research Council of Ontario. It is a method of 

 printing aerial photographs, in which the "dodging", or variation of light intensity 

 behind various sections of the negative (which is usually carried out by the use of 

 a large number of small individually controlled lights) is accomplished by using a 

 fuzzy diapositive. This is made from the negative itself and fastened in register 

 behind it. Thus, the dense portions of the negative receive proportionately more light 

 than the thin; at the same time, the contrast between images of contiguous fine detail 

 points is preserved. At present this method is in use in this Department for special 

 prints where the ultimate in detail perception is required. The Hydro-Electric Power 

 Commission has requested that all their enlargements and contact prints for mosaics 

 and contouring, be unsharp masked. 



During the past fiscal year the vertical photography carried out by the 

 Aerial Surveys Section totalled 3.471 square miles. 



Of this total. 656 square miles were for our own Department and 2,815 square 

 miles were for other Government Departments. A table showing a breakdown of these 

 figures is submitted herewith. 



During this same period the expenditure was $50,698.18 and the revenue 



$33,479.54. 



Table No. 3 

 Other Government Departments 



AREA 



(sQ. miles) totals 



Hydro-Electric Power Commission „ 186 



**Flanning and Development 1,766 



Highways 863 2,815 



Department of Lands and Forests 



*Forest Resources Inventory — ._ 648 



Other . 8 656 



TOTAL 3,471 



♦Denotes Mapping Included. 

 **Denotes Multiplex Work Included. 



Total of Aerial Surveys — 1924 to 1951 (March 31) 



Aerial Sketching _._ .._ 26,903 Sq. Miles 



Oblique Photography 10,780 Sq. Miles 



Vertical Photography 114,037 Sq. Miles 



