(Lähde: MIL 100 vuotta 1990, Maanmittausinsinöörien Liitto, Jyväskylä, 1990)
Professor Halonen began his studies at the Helsinki University of Technology in 1935 and graduated in 1941. In 1951 he defended his doctoral thesis on the determination of the accuracy of exterior orientation in aerial photogrammetry.
Dr. Halonen started his academic career as assistant in photogrammetry and geodesy at the Helsinki University of Technology. During the years 19471949 he worked as research assistant with Professor Bertil Hallert at the Institute of Technology in Stockholm. Upon his return to Helsinki he continued at his own university first as lecturer and then, from 1956 to 1960, as docent in photogrammetry. Thereupon he was appointed to hold the chair of photogrammetry, the first professorship in photogrammetry in Finland.
As Professor in Photogrammetry, Dr. Halonen concentrated on the development of analytical photogrammetry, devoting special attention to the study of the accuracy of the bundle adjustment. As Director of the Institute of Photogrammetry, a creation of his, he resolutely improved the instruction given in photogrammetry and promoted photogrammetric research to a high level even by international standards.
The Helsinki University of Technology had the benefit of Professor Halonen's talents also in administrative matters. He was Head of the Department of Surveying from 1961 to 1968 and again from 1973 to 1974, and Pro-rector of the Helsinki University of Technology from 1970 to 1973.
Most of Professor Halonen's publications are in the field of photogrammetry. However, he also wrote shrewdly on student politics and educational policy. For many years he was Head of the Board of the Photogrammetric Journal of Finland.
It was as trainee at the Photogrammetric Laboratory of the Defense Forces in 1937 that Professor Halonen came into contact with the field of photogrammetry. Later on, during the Second World War, his knowledge of photogrammetry, his organizational talents and his investigative mind were to provide most valuable to the Army Map Service as he participated in extensive projects of aerial mapping. In part, it was due to his energetic activity that methods of aerial photogrammetry for mapping purposes were widely adopted in Finland soon after the War.
From the very beginning, Professor Halonen contributed to the development of professional organizations in his field. In recognition of his activities, he was appointed Honorary Member of the Finnish Society of Photogrammetry when it celebrated its 40th anniversary in 1971. Professor Halonen was on the Steering Committee of the European Organization for Experimental Photogrammetric Research. He was Chairman of ISP Commission Vl from 1960 to 1964 and Member of the ISP Council from 1968 on. At his death Professor Halonen served the ISP as Congress Director of the XlIlth International Congress for Photogrammetry to be held in Helsinki in 1976.