J. RONALD EYTONRICHARD P. KUETHER'University of Illinois

Urbana, IL 61801

Macrophotography ofSatellite Images

The enlargement of Landsat and Skylab images on high­definition, high-contrast film enhances details and aids ininterpretation.

L ANDSAT AND SKYLAB imagery may beenlarged to improve the examination of

detail contained in the images. For continu­ous tone photography, such as obtained bythe Skylab missions, the limit of enlarge­ment is determined by the resolution of thefilm product and the final resolution of theenlargement acceptable to a viewer or inter­preter. The resolution of an enlarged photo­graph acceptable for interpretation or view­ing is a resolution (approximately 8 linepairs per millimetre) slightly better than theresolution of the human eye (5 to 6 line pairsper millimetre). The maximum enlargementa photograph should undergo would then be

and 5 line pairs per millimetre for the1:500 ood product. By conventional stan­dards the 1:500 000 products have less thanan acceptable viewing resolution.

For purposes of mapping detail, both theSkylab a~d Landsat images can be enlargedbeyond the limits of normal viewing resolu­tions. If a high contrast film material is usedto copy the satellite image, the results maybe a duplicate with less than "acceptable"viewing ~esolution but an image that showsan increase in acutance or sharpness. Wehave found that carefully produced macro­photography will produce useful images atscales of 1:60 000 and, in some instances, at

ABSTRACT: A simple method for the production of high quality ma­crophotography of satellite images using an enlarger is outlined. Alist of unconventional films found to be useful for copying andenhancing detail is included.

equal to the film product resolution dividedby the acceptable viewing resolution of 8line pairs per millimetre. For example, themaximum factors of useful enlargement forthe Skylab high-resolution color photog­raphy obtained by the multispectral cameraand the Earth terrain camera are shown inTable 1.

The resolution of images obtained from anelectro-optical sensor such as the Landsatmultispectral scanner is usually more diffi­cult to assess. For Landsat the nominalground resolution is about 100 metres withthe equivalent photographic resolution forthe Landsat 70 mm film product (1:3 369 000)estimated at 34 line pairs per millimetre.This would be a resolution of 10 line pairsper millimetre for the 1: 1 000 000 product

scales larger than 1:60 000. Although a num­ber of cdnventional methods and materialsare readily available for closeup photog­raphy, this note discusses an inexpensivebut unconventional method of copying andsome unconventional film materials.

COPYING

We have used two methods for the macro­photography of Landsat and Skylab images.The first ~nethod uses a conventional 35 mmsingle lens reflex camera and macro lens forcopying 1: 1. Several useful films are avail­able in 35 mm format only and this type ofcamera system requires little fussing forsmall mJgnification (down to 1: 1) photog­raphy.

1019PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING,

Vol. 44, No.8, August 1978, pp. 1019-1021.

2 r =

1020 PHOTOGRAMMETRIC ENGINEERI G & REMOTE SENSING, 1978

TABLE 1. ENLARGEMENT FACTORS FOR HIGH RESOLUTIONS COLOR IMAGES FROM THE SKYLAB MISSIONS

Estimated Estimated NominalGround Photographic Contact Enlargement Enlargement

Camera Resolution 1 Resolution2 Scale Factor Scale

Multispectral(S-190A) 43 metres 66lp/mm 1:2850000 8.2x 1:350000

Earth Terrain(S-190B) 21 metres 45lp/mm 1:950000 5.6x 1:170000

I Low contrast estimated resolutions fromSkylab Earth Resollrces Data CatalogCPO 3300·00586

scale #R x!OOO

r = photographic resolution (line pairs per millimetre)R = ground resolution (metres per line p<lir)

A second method especially suitable forhigher magnification photography employsan enlarger and film magazines (sheet androll) as the camera system. Figure 1 showsthe necessary components. One side of the4 by 5 inch sheet film holder can be used forfocussing by inserting a white 4 by 5 inchsheet of paper in the film slot with the darkslide removed permanently. The dark slide(usually aluminum) of the roll film holdercan be used to focus the image. However,the dark slide will be at least Va in. above thefilm emulsion; therefore, before exposurethe film holder should be raised VB in. byplacing a spacer (cardboard sheet) beneathit. Centering of the image can still be done

FIG. 1. Film holders for macrophotographyunder the enlarger: left, 4 by 5 sheet film holder;right, 120 roll film holder.

on the dark slide (do not refocus) beforeexposure.

The Landsat or Skylab transparencyshould be placed in the enlarger correct­reading down; or another way to visualizethe proper positioning of the transparencywould be to take out the enlarger lens andlook through the lens holder at the trans­parency in the film holder-the transparencyshould be the correct reading. The properpositioning of the transparency in the en­larger is important if the copy film is a nega­tive material from which prints are to bemade at a commercial laboratory.

LIGHTING

Copying imagery is usually done withphoto-materials balanced for either tungsten(32000 K) or daylight (58000 K) lighting. Whenusing the 35mm single lens reflex camera,either an Aristo DA-110 transparency illumi­nator (5800 0 K light) or a light box with awhite plexiglass diffuser and 250 watt 32000 Kbulb is used to illuminate the image. Theenlarger method of copying requires thatcolor balancing filters be attached to the en­larging lens to match film and lighting.Table 2 shows the necessary filtration forthree standard enlarging bulbs.

FILMS

For general purpose copying most colornegative and transparency films will yielduseful results. It is usually not necessary touse special copying films for control of con­trast and, although there will be an increasein contrast using conventional films, wehave usually found this to be desirable whencopying satellite images. Several unconven­tional films that have produced good to ex­cellent results are given in Table 3. A filmwith which we have experimented that isparticularly useful for enlarging images is

MACROPHOTOGRAPHY OF SATELLITE IMAGES

TABLE 2. ENLARGER BULBS AND COLOR BALANCING FILTERS FOR BALANCINGTUNGSTEN AND DAYLIGHT FILMS

Color Balancing Filters

1021

Enlarger Bulb

211 (75 WATTS)212 (150 WATTS)300 (150 WATTS)

Bulb Color Daylight Films Tungsten FilmsTemperature (5~00OK) (32000 K)

29500 K80B & 80C 82B

29500 K31000 K 80B & 82B 82

TABLE 3. FILMS FOR COPYING SATEJLlTE IMAGES

Film Lighting Format Use

Eastman Kodak 5247 color 32000 K 35mm An excellent film for copying which yieldsnegative film (used in the motion images that faithfully reproduce the original'spicture industry and readily color. Most distributors of this film offer a fullavailable from special distrib- range of ~ervices including slides and printsutors).* from the hegatives at exceptionally low prices.

Eastman Kodak Photo- 58000 K 35mm A very high contrast color transparency film formicrography Color Film 2483 4 x 5 copying and enhancing images. Some experi-

mentation with color correcting (CC) filters mayimprove the renditions. (Cover photo.)

Eastman Kodak Vericolor II 32000 K 120 A color n~gative film for long exposures (longerProfessional Type L 4 x 5 than 1110 second). Useful for producing color

negatives under the enlarger.

Eastman Kodak High-Contrast 32000 K 35mm A panchromatic very high contrast copy blackCopy Film 5069 and white film useful for close-up photography

and enhancing detail.

* Most popular photographic mag<l.zine~ carry several advertisements of companids that sell and process this film.

Eastman Kodak Photomicrography Colorfilm (2483). This high-definition, high­contrast transparency film can be used forthe enhancement of detail and the furtherdifferentiation of boundaries between areason the image that differ slightly in tone andcolor. Careful exposure is required (bracketall shots ± V2 and 1 stop) because ofthe small

exposure latitude. The cover photo (Cham­paign-Urbana, Illinois, population 100,000)was obtained on Photomicrography ColorFilm from a Landsat 7.3 inch color printcopying at 1: 1 with two 32000 K floods andan 80A filter.

(Received April 13, 1977; revised and acceptedMarch 14, 1978).

Forthcoming Articles

Dipl.-Math Hanspeter Bopp and Dipl.-Ing. Herbert Krauss, An Orientation and CalibrationMethod for Non-Topographic Applications.

Dr. Uzi Ethrog, Photogrammetric Positioning of Supersonic Wind Tunnel Models.Alan D. Jones, Computers and the Teaching of Airphotd Interpretation.D. L. Lawton and D. F. Palmer, Enhancement of Linear Features by Rotational Exposure.V. R. Rao, E. j. Brach, and A. R. Mack, Crop Discriminability in the Visible and Near Infra-

red Regions.Arnaldo M. Tonelli, Surface Texture Analysis with Thermal and Near Infrared Scanners.Charles W. Welby, Application of Landsat Imagery to Shoreline Erosion.P. A. Murtha, Symposium on Remote Sensing for Vege~ation Damage Assessment.Peter A. Murtha, Remote Sensing and Vegetation Da~age: A Theory for Detection and

Assessment.Robert C. Heller, Case Applications of Remote Sensing for Vegetation Damage Assessment.Thayer Watkins, The Economics of Remote Sensing.