Dr. Kim Iles, biometrician and consultant on Forest Inventory in British Columbia, Canada, has issued three books, which are very interesting for people who are only related to the field as well as to students and to professional biometricians.

Book One “A Sampler of Inventory Topics” (printed 2003, 2004, 2015)
The intended audience is measurement people (forestry and otherwise) who probably know the basics and want more depth, and those that want a practically useful background in sampling.  It covers Statistics, Variable Plot Sampling and 3P sampling in detail.

Book Two “The Compassman, The Nun, and the Steakhouse Statistician” (printed 2009)
The intended audience is forest inventory professionals, young biometricians or those with statistical training, and those who have to solve practical sampling problems and wish to get beyond equations and grasp some. Each chapter examines practical issues of sampling, professional development, or statistical techniques.

Book Three “The Retread, The Reject and the Tower Statistician” (printed 2014)
They are especially suitable for studying the forest inventory methods in Northern America, but I am sure that anyone else would find it very interesting. For further details please refer to Kim´s website

In co-operation with the BOKU-University of Natural Resources and Applied Life Sciences at Vienna, Austria, a video was produced featuring Prof. Dr. Walter Bitterlich – his life, his method and his inventions. The method of Angle Count Sampling is explained very well so that even non forestry people can understand it very easily.

There are still some books “The Relascope Idea – Relative Measurement in Forestry” by Dr. Walter Bitterlich available!


Walter Bitterlich passed away on February 9th, 2008 – 10 days before celebrating his 100th birthdayBi
Prof. Dr. Bitterlich Walter Bitterlich, who revolutionized forest inventory methods throughout the world with his pathbreaking discovery of “Winkelzählprobe” (“angle-count sampling”), celebrated his 100th birthday on 19 February 2008. Born on 19 February 1908 in Reutte in the Tirol, Austria, he graduated Diplom Ingenieur at Hochschule fur Bodenkultur in Vienna, Austria, in 1930. Initial ideas about the angle count method are documented in his diary as early as 1931. However, the need for gainful employment and the interruption of professional and scientific work by service in the German army during World War II meant that he would not be able to finish development and publication of his theories until 1948. This new method of determining basal area per unit area without direct measurement of either plot areas or tree diameters quickly spread around the globe as it proved to be a highly efficient and economical inventory tool and it soon became regarded by many foresters as the “invention of the century”.

The method is known by many different names including “angle-count sampling”, “Bitterlich method”, “plotless crusing”, “variable-plot sampling”, and “point sampling”. A 1952 Journal of Forestry article by L. R. Grosenbaugh was pivotal in introducing Bitterlich’s method to American forestry practice. Since that time, hundreds of papers on various aspects of angle count sampling have been published as it became the standard method for efficiently obtaining estimates of basal area, volume, and numbers of trees in forested areas. In addition to sighting trees at dbh, which is sometimes called “horizontal point sampling”, methods have been developed to project vertical angles and select sample trees based on their height (“vertical point sampling”). The angle count concept has been applied for a wide range of inventory situations, including recent extensions for assessing downed logs and coarse woody debris.

In addition to his pioneering contributions to methods of forest sampling, Dr. Bitterlich is a prolific inventor who holds many patents. Since 1950, he has worked closely with FOB, now Relaskop-Technik, in Salzburg, Austria, to develop the appropriate tree measuring devices for his method of angle count sampling, such as the Spiegel-Relaskop and the Tele-Relaskop. These instruments are still state of the art and used worldwide for making forest measurements, especially inventory.

Since the 5th World Forestry Congress of the FAO in Seattle USA Prof. Bitterlich has participated in nearly all World Forestry Congresses and IUFRO World Congresses as well as in numerous IUFRO Symposiums with invited papers and presentations of his instruments.

In 1966 Dr. Bitterlich was appointed professor at the University of Agriculture (BOKU) in Vienna, Austria. After his retirement in 1978, he continued his scientific work, which was summarized in a book, “The Relascope Idea”, published by the Commonwealth Agricultural Bureau in 1984. Over the years he has made presentations at numerous meetings and he has received countless visitors in his home and office in Salzburg. He is a warm and gracious host; for many forest mensurationists, a pilgrimage to Salzburg to visit Dr. Bitterlich stands out as a high point in their careers. Dr. Bitterlich has received many awards in Austria and Germany and he is an honorary member of the Society of American Foresters.

The creative genius of Walter Bittterlich is rare and he is greatly admired throughout the forestry scientific community. His work has proved to be both intellectually interesting and highly practical. Prof. Bitterlich passed away on February 9th, 2008, ten days before his 100th birthday. He was burried in Reutte/Tyrol in a cenotaph.

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In co-operation with the University of Agriculture at Vienna a video was produced featuring Prof. Dr. Walter Bitterlich – his life, his method and his inventions. The method of Angle Count Samling is explained very well so that even non forestry people can understand it very easily.

The video is available in English in the PAL-system as well as in the NTSC-system. The price for 1 video is EURO 8,80 + shipping costs for PAL and EURO 12,50 + shipping costs for NTSC. If interested please contact us.

Our company has issued new manuals Spiegel-Relaskop “Wide Scale” and “American Scale”. They are available free of charge. Please ask for it.