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When and how we met

So, how did fate arrange for a boy born in a small village in Southern Germany, and another born a few years later in a town in Egypt, to meet and become life-long colleagues and friends? In 1964 Fritz was a lecturer at the ITC, while I was a brand new PhD in photogrammetry working at Canadian Aero Service Ltd., in Ottawa, Canada. My Cornell Univ. professor and I had written a paper on Photo Triplets to be presented at the Pre-Congress Symposium at the ITC. Instead of letting me present it (being part of my PhD work), he decided to do it himself. Now, prof McNair, who was a kind old gentleman, had a special flare for the dramatic. So, he began the presentation with “In the beginning God created man with two eyes and in 1963 Ed Mikhail created the three-eyed man”. The audience was in stunned silence for a few minutes, … followed by roaring laughter. In the words of Dr. Proctor in the Photogrammetric Record, “. . . hobby horses were ridden and all had fun at the expense of Padre McNair”. . . and of course yours truly who could not find a hole to hide in. Remember, I was a young fellow in Europe for the first time, and did not know a single person in attendance. Enter Fritz Ackermann! After the session he was the only one who came up to me, introduced himself and proceeded to tell me not to take it hard. Not only did he attempt to nullify the impact of the debacle, but he also expressed interest in the concept. As you realize, ladies and gentlemen, this was over 45 years ago, and yet I still remember it as if it happened yesterday. It is this single act of kindness and understanding in my opinion, that totally characterizes Fritz the true gentleman. It was the beginning of a long and sustained friendship. One can only conjecture as to how my progress would have been impacted if this incident had not happened.

What made that incident the more remarkable is that I had already heard of him and nearly became one of his students. Originally, I was supposed to go to the ITC for a Masters in 1960, but circumstances lead me instead to the U.S. His excellent reputation as an educator, particularly in teaching Least Squares, was well known to me, and I truly looked up to him. So, it was doubly more appreciated that he had approached me . . . a totally unknown quantity to him. This, in my book, speaks volumes about him as a person. We continued our interaction and technical discussions at the Lisbon Congress in 1964. The more he showed interest in my work and my thoughts, the more I was determined to emulate his path to success in photogrammetric education and research. I was reminded of another incident, recalled by our mutual friend, Prof Jim Anderson of Berkeley, and I quote “The first time I met Fritz was at the Symposium on Analytical Photogrammetry at the University of Illinois in Champaign-Urbana in 1966.

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I vividly recall the ITC crowd (and Jim calls the “Inquisitors”) seated in one of the first three or four rows (not so close as to be conspicuous, but close enough to be noticed) which also included Fritz. In particular, I remember how systematically they dissected the presentations of two young gentlemen”

Whereas others were vehement in their criticism, I recall that Fritz was again the true gentleman by talking to the authors after the session, making recommendations for corrections in order to salvage their work. He never appeared to take any pleasure in seeing others suffer, without ever compromising his stance for rigor and quality.

Our friendship grew and was cemented when he invited me to spend some months in Stuttgart during my first sabbatical leave in 1971.

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He was very kind not only to me but also to my family. My little girl used to call him uncle FITS when we went for outings. And I remember most fondly the time we spent working together in his cottage in the black forest.

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His Working Career

I cannot do justice to this gentleman’s collossal career in the time I have. So, briefly here are the chronological phases of his professional activities.

· He started his education in Physics in 1950 at Tubingen University and continued at the Technical Univ. of Stuttgart earning a Dipl. Ing in 1954

· Joined Zeiss Oberkochen in 1954 until 1958, working on testing and calibration of photogrammetric instruments

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· Lecturer at ITC 1958 to 1966

· Masters 1961, ITC and Doctorate, 1964, Stuttgart

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· At the young age of 37 he became Prof. and Director of the I.f.P, Stuttgart and remained until he retired from the Univ. in 1992

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So, What has he done that is noteworthy?

Let us compare the state of photogrammetry in the mid 1950s when he started his career, and the present. I hasten to say that I am not suggesting that Fritz single-handedly accounts for the explosion in its technical development. What I am saying, though, is that he has been one of the pillars on which that development has been built. At the beginning of his career, photogrammetric practice was essentially based on analog representation of the imaging process. True that there was very early attempts at numerical adjustment, as for example by Vermier. Fritz, however, started the formal and systematic application of Least Squares to first the adjustment of strips, and rigorous error propagation therein,

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and the theoretical work on piecewise connected third order polynomials may be considered the first area of this research work.

The second area of this research involves analytical block

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adjustment on which he worked extensively for two decades. No one at that time,

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or indeed now, would talk about block adjustment without associating it with Ackermann. It was almost as if one is synonymous with the other. There were of course other researchers, notably Duane Brown in the U.S., who also worked in parallel on the bundle approach. Fritz, shrewdly started with the independent model approach because it was more practical then given the computational limitations, and he wanted to process more than 1000 units. Intensive effort was spent on developing fast solutions. The result was one of the most widely adopted packages, PAT M. The next logical step was to develop the PAT B, for analytical bundle block adjustment.

In parallel to S/W development many exhaustive theoretical investigations were performed to assess accuracy and the amount and distribution of control points. The theoretical work was supplemented by empirical testing such as the many-year effort through OEEPE. A most beneficial and impressive outcome was the application to very high precision cadastral survey using signalized points, and the combined adjustment with terrestrial data.

Another area of creative work covered self-calibration employing added parameters in the adjustment to accommodate residual systematic errors, as well as automatic detection of blunders or outliers. As an alternative, was the approach of least squares interpolation of the adjusted block, with contributions by the late Prof Carl Kraus who did his habilitation with Prof Ackermann. The driving force had been to produce the highest accuracy attainable with the least amount of geodetically determined ground control points. The logical next step was then to include GPS aboard, and develop and test the necessary techniques

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of combined adjustment thus in essence making each camera position a

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control point leading to marked reduction in ground control.

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The concept was rather revolutionary at the time . . . although we take it as a common practice at present.

If anyone can claim the lion’s share of the development of block triangulation, Fritz can. Another logical phase thus, was the studies and investigations of internal and external reliability of image blocks which, to the surprise of some at that time, compared favorably to geodetic networks.

Somewhat in parallel, and through the initiative of Prof Kraus, a whole new area of investigation was initiated, dealing with digital elevation models. This resulted in the well known SCOP program and

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the exploitation of least squares interpolation. Although, there had been other efforts at automated extraction of DEMs, the systematic and methodical development of SCOP makes it an unqualified success. It started with thousands, and then 10s of thousands of points. It also recognized that significant points, breaklines, etc. must be realistically accommodated. From DEMs, contour lines were digitally produced and

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critically evaluated in order to satisfy the cartographers who were rather skeptical. It must be fully gratifying to Fritz to see the effort that was in its infancy in the early 1970s, grow and mature into the present Match-T by the Inpho Company that can produce over 50 million points per project.

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I recall that I was taking a long walk with Fritz in the black forest discussing the state of affairs of photogrammetry . . as we regularly did when I visited Stuttgart. We agreed that the whole area of triangulation and DEM had matured, and a new direction of development is dawning . . that of digital imagery and incorporation of digital image processing into photogrammetry. I had begun using least squares to extract edges from digital images, and he had already started exploiting least squares image matching which was later extended to feature-based matching.

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The incredible small fraction of a pixel accuracy was a remarkable achievement which ushered in the extensive use of the method, culminating in full automation of aerial triangulation, and of extraction

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of DEMs from overlapping imagery. One very successful application of that development is the automatic measurement of car bodies by photogrammetry used by VW for many years until replaced by laser scanning.

As if in anticipation of the profileration of digital imagery from space, Fritz was the principal investigator for image data and application of the German MOMS Project.

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It was a digital space camera with linear array sensors that flew on the Space Shuttle in early-mid 1990s. Now we look at Digital Globe or GeoEye imagery and not give it a second thought, being so prevalent.

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Awards and Recognitions

I do not know of anyone who has as many world-wide awards and recognitions, and by consequence, as deserving as Fritz. He was recognized and rewarded starting early in his career and continued well after his retirement and as recently as this year. His accolades are so numerous and far-ranging that I can only list the most prominent:

· The otto von Gruber by ISPRS in 1964 the year he earned his PhD

· In 1976, at the young age of 47, he won the highest ISPRS Award, the Brock Medal

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· Then the following succession of international recognitions

· Honorary professor, Wuhan, China, 1989

· Honorary Member of the following Photogrammetric Societies

· British 1989

· U.S. 1995

· ISPRS 1996

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· German 1999

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· Honorary Doctorates from the following Universities

· Helsinki 1988

· Vienna 1991

· Hannover 1995

· Moscow 2009

· The Photogrammetric (Fairchild) Award, ASPRS, 1999

· ITC Fellow, 1992

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But, it is not all work

Anyone who knows Fritz, recognizes how multifaceted the gentleman is. He is as fun loving as anyone I ever met with great sense of humor and a hearty and infectious laugh. He is certainly an excellent skier

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and Mountain Climber

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and an accomplished pianist

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Fritz can have as much fun as any one:

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Riding an elephant in Thailand w/o proper license

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Lasso throwing in Finland

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Showing his fitness in Rovaniemi, Finland in 1986

The Last Word

To sum it up, here is what an esteemed colleague, professor John Trinder, of Australia, who first met Fritz over 46 years ago:

“I first met him in 1963 when I was a student at ITC. I found him to be a thorough and excellent teacher who was very sympathetic to his students. I was very fortunate to have him as a teacher since it established the foundation to my knowledge of adjustment in photogrammetry during my career.

In ISPRS he is only one of two scientists to have received the von Gruber Award and the Brock Medal as well as Honorary Membership of ISPRS. During his career, he travelled widely giving lectures to many local societies, which I know were really appreciated in Australia. He was always willing to give others the benefit of his photogrammetric knowledge to colleagues around the world.

He was a keen mountain climber and I always remember his story of renting a car in Tokyo, driving to the base of Mt Fuji, climbing it and then returning to Tokyo in time for his plane, in a period of a little more than 24 hours.

I found him an excellent and sympathetic sounding board on policy issues in ISPRS when I was President of ISPRS from 2000-2004. His advice was very measured and helpful. He has been and still is an outstanding leader of the photogrammetric community and I wish him a very enjoyable 80th birthday and continued good health in the years to come”

The greatest satisfaction for those who work in higher education, is the success of their students. In a way it is as if they are continuing their work through their graduates. They continue to carry the torch of advancement to the full satisfaction of the educator. Prof Ackermann should most certainly be well satisfied with the impact his students have had on advancing the state of the art of photogrammetry.

Current young photogrammetrists who contribute to its continued development must not forget that they see farther into its great future only because they stand on the shoulders of preceding giants like professor Ackermann.

My father had told me as a youngster, count your wealth by the quality of true friends. I feel that I am truly a wealthy man having had Fritz as my friend. It has been an honor and privilege knowing him.

Thank you.

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