Remote Sensing: The NIWARS period (1971 – 1977)

 

Remote Sensing: The NIWARS period (1971 – 1977)

 
The Dutch Interdepartmental Working Community for Application Research of Remote Sensing Techniques (NIWARS) started running in 1971, after the NIWARS Steering Committee was established on 1 January 1971. At the same time, the discussion about the balance between applied research and background research started. When NIWARS started, very little was known about the domain backgrounds. For example, virtually no knowledge about the reflective properties of vegetation, land, or the sea was required for all conceivable Remote Sensing applications. There were already some results in America with multiband scanners and the LANDSAT satellite (then still called ERS) was on the way. Study trips to the US [12] soon showed that the choice of frequency bands had been quite arbitrary. At best it was based on literature research, but certainly not on specific experiments of our own. It only became clear later that the choices could be far from optimal and that they often were. They were purely technical. They wanted to have several systems flying. After that they saw further, or, as they put it more neatly, it was up to the user, whoever that might be. 
They appreciated the more fundamental proposals by TNO but did not know how to implement them themselves and were therefore fully prepared to cooperate. However, they also already had several nice and promising results that gave them hope for the future. These study trips to the US also created an important contact for radar work with the Remote Sensing Laboratory of Kansas University (the group of Prof. Dr. R.K. Moore, who would later develop the wind scatterometer).
So one of the questions posed at the start of NIWARS was to find out whether the proposed ideas work. If so, optimise these and gain new ideas through good and targeted object-sensor interaction studies. Or just fly straight away, look at pictures and fall on your face. The latter approach, which seems so practical and applied, was difficult to reconcile with the results of the previous history outlined earlier in these web pages. However, the researchers did not take into account the fact that as the circle grew, new people were added to committees and working groups. They did not have the experiences that had been gained in ten years (from 1960). A compromise was found and background research was done in all three windows in the NIWARS period:

  1. Visible light and near-infrared
    In a good mix of experiment and theory, Bunnik and Verhoef first succeeded in demonstrating that detection, identification, etc. is possible with colours. They then succeeded in filling in this insight in such a way that sensible frequency band choices for this window have become possible [13]. They used a field spectrometer specially developed for this purpose by TPD-TNO.
  2. The microwave window
    For this purpose, the so-called Radar Research on VEgetation team (ROVE) was established, a multidisciplinary working group that energetically started building a data file via radar measurements on various crops spread over the entire growing season [14]. A short-range radar reflectometer developed at TU Delft and test fields from CABO in Wageningen were used for this purpose.

    Crop classification by remote sensing
    Crop classification by remote sensing
  3. The heat window
    A start was made on modelling. Afterwards, this last window turned out to be one of the most physically difficult to access because of the many parameters that can influence the result.

As noted before, special measuring equipment had to be developed and built for all these investigations, because much was not for sale. This all happened in the Netherlands by the participating institutes. None of the intended NIWARS studies came to a definitive conclusion during the NIWARS period.

Only the radar work in the ROVE team managed to survive after this period and could continue its work until it was taken over by the Remote Sensing Policy Committee (BCRS).

For a more complete report on NIWARS, reference is made to the Final Report NIWARS [15], which appeared in 1977. For the further history of Remote Sensing in the Netherlands, including that of the two BCRSs up to 1988, reference is made to the publication of Mr Morra on behalf of the ‘Kring voor Remote Sensing’ [16] and also [17].

Summary

In a general sense, it can be noted that between 1971 and 1977 NIWARS made an essential contribution to making Remote Sensing known in the Netherlands. In several places, it has led to high-quality scientific research that has enjoyed great international recognition. The researchers were also able to make a substantial contribution to the preliminary research and the proposals for ESA‘s first radar satellite. Our approach to Remote Sensing, with a lot of background research, especially on the “input side”, was sometimes referred to abroad as “the Dutch school”. It certainly gave the Netherlands a prominent position in the field of work until the early eighties.

Acknowledgement

Dr.ir. G.P. de Loor gave a lecture on 7 June 1988 on the occasion of the 10th anniversary of the “Kring voor Remote Sensing” on 17 August 2009. He wrote down the basis for this text. His lecture also appeared in an interim version in the Remote Sensing Newsletter no.95 of December 2000 at the closing of the NRSP. 

References
  1. J.Ph. Poley: “Note on the resolution of radar systems”; Tijdschrift Nederlands Radiogenootschap, vol.22, 1957, pp. 187 – 194. 
  2. H.M. Oudshoorn: “The use of radar in hydrodynamic surveying”; Procs Seventh Conference on Coastal Engineering, edited by J.W. Johnson (The Hague: Council on Wave Research, The Engineering Foundation), 1960, pp. 59 – 76.
  3. G.P. de Loor, A.A. Jurriëns, W.J.M. Levelt and J.P. van de Geer: “Line-scan imagery interpretation”; Photogrammetric Engineering, vol.34, 1968, pp. 502 – 510.
  4. G.P. de Loor, A.A. Jurriëns and H. Gravesteijn: “The radar backscatter from selected agricultural crops”; IEEE Trans. Geoscience Electronics, vol. GE-12, 1974, pp. 70 – 77.
  5. G.P. de Loor, “Possibilities and uses of radar and thermal infrared systems”, Photogrammetria, vol.24, 1969, 43 – 48.
  6. RWS werkgroep, nota: “Radar en infra-rood luchtopnamen”, door Afd. Havenmonden bij brief nr. 128 dd. 10 jan. 1969 aangeboden aan de HID RWS in de Directie Benedenrivieren.
  7. ITC rapport: “Voorstel tot applikatie onderzoek van moderne lucht-opname technieken”, aangeboden aan de Minister van O en W, 10 jan. 1969.
  8. Interdepartementale Werkgroep Applikatie Onderzoek Moderne Luchtopname Technieken: “Concrete voorstellen voor het applicatie onderzoek van moderne luchtopname technieken”; Nota op 5 dec. 1969 uitgebracht aan de Minister van O en W, mede ten behoeve van zijn ambtgenoten.
  9. Verslag van het Symposium “Luchtwaarneming met niet-conventionele systemen”; De Ingenieur, vol.33, 1970, Afd. TWO nr.6 pp. o71 – o100 (6 artikelen, verslagen van het werk verricht van 1962 tot 1969).
  10. W. Alpers and I. Hennings: “A theory of the imaging mechanism of underwater bottom topography by real and synthetic aperture radar”; J. Geophys. Res., vol.89, 1984, pp. 10529 – 10546.
  11. Maritiem Geodetisch Bureau C. Don: “Proefopnamen met side looking airborne radar”; rapport samengesteld in opdracht van RWS, Directie Benedenrivieren, Afd. Havenmonden, Sectie Noordzee, 1970. Een herdruk verscheen in de RS Nieuwsbrief nr. 89, dec. 1999.
  12. “Verslag van een oriëntatiereis door de USA door een W.A.C.-delegatie in de periode van mei-juni 1971 in opdracht van de Stuurgroep van NIWARS”; ingediend door de voorzitter van de Stuurgroep op 15 nov. 1971.
  13.  N.J.J. Bunnik: “The multispectral reflectance of shortwave radiation by agricultural crops in relation with their morphological and optical properties”; Thesis Wageningen, 18 Jan 1978, also in Comm. Agricultural university Wageningen, 78-1 (1978).
  14. G.P. de Loor, P. Hoogeboom and E.P.W. Attema: “The Dutch ROVE Program”; Trans. IEEE Geosci. and RS, vol.GE-20, 1982, pp. 3 – 11.
  15. Eindrapport NIWARS, rapport uitgebracht door de Stuurgroep van het beleidsruimte project NIWARS, 1 juni 1977.
  16. R.H.J. Morra: “Het begin van de remote sensing in Nederland”, 1958 – 1986”; publicatie van de Kring voor RS, maart 1990.
  17. L. Krul en G.P. de Loor: “Experiments with microwaves”; Int. J. Remote Sensing, 1992, vol. 13, nos. 6 and 7, 1201-1216.