FIG.!. LogEtronic SP 10/70 printer (left) and Kodak Versamat (right).

RAY J. MEEHAN, PresidentAtlantic Aerial Surveys, Inc.

Huntsville, AL 35801

Increasing ProductivityIn PhotogrammetryIn today's economic climate, management is pressed to findways of increasing the productivity of its people with equalor better quality of service.

(Abstract on next page)

T HE MANAGEMENT of a commercial photo­grammetry firm has essentially the same

basic objectives as any other business organi­zation: healthy growth in sales and profit byproviding a good product at a fair price. To doso, the firm must invest in the equipment andmust carry the labor overhead that are neces­sary to maintain quality of service as volumeexpands. The cost can be particularly bur­densome in photogrammetry because muchof the specialized equipment is so expensiveand, more important, the people who operateit command such high salaries. In today'seconomic climate, management is thereforepressed more than ever to find ways of in-

creasing the productivity of its people withequal or better quality of service.

In our experience at Atlantic Aerial Sur­veys, automation can playa major role in ac­complishing these objectives. Although it is aword that has been given many definitions,the one that applies best in photogrammetrydescribes automation as the mechanizing ofall those operations that can be done as wellor better by specialized equipment so thathuman perceptions and skills can be appliedmore in the operations that machines cannotdo at all. However capable the device, thehuman eye and human judgment will alwaysbe needed at a stereoplotter. But an automat-

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754 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1975

ic processor can develop, fix, wash and drymore photographic paper or film in an eight­hour shift than the most capabletechnician-and, as long as there is adequatevolume, do it at a far lower unit cost. Automa­tion can also improve quality control in that itcan provide better, more consistent aerialimages wherever they have to be used.

In two quite different areas automation hassignificantly increased productivity. First,automated equipment is used for developingroll film and paper and for exposing paperthrough aerial negatives, both with aminimum of human attention. Second, vari­ous data-reduction devices are used tohandle the vast amount of photogrammetricdata that are generated, and a computer per­forms many of the more complex computa­tions that were once done manually with thehelp of desk calculators.

The improvements in quality control haveto do with the various forms of images in

film/paper processor (Figure 1, right) and theLogEtronic SP 10170C electronic strip printer(left). Rolls of black-and-white aerial filmnegatives are developed in the processor, rollpaper is exposed in the strip printer, and theprints are then developed in the Versamatprocessor.

The speed ofthe processor ranges between12 and 14 ftlmin for flIm or paper, completinga 250-ft roll in somewhat less than 20 min­utes. The SPlO170C printer, which exposespaper through normal negatives at between36 and 40 ftlmin, takes between 6 and 7 min­utes to print a roll. The film/paper processorcan be used with the same chemistry for bothfilm negatives and paper simply by changingthe content of potassium bromide in the de­veloper and the replenishment rate of thedeveloper and fixer. However, if the volumeofwork is large enough, one processor is usedfor negatives and a second for paper prints.

The increase in productivity achieved with

ABSTRACT: Atlantic Aerial Surveys, Inc. applies manpower-savingphotogrammetric instruments to facilitate the production of mapsand data. A Kodak Versamat film/paper processor used in conjunc­tion with a LogE strip printer enables the printing ofa roll offilm inhalf the time needed formerly, as well as providing improved qualitycontrol. A Kern PG-2 plotter is equipped with digital readout so thatthe output data can be transmitted directly to a computer for deter­mining the volumes ofstockpiles. A Kern MK2 monocomparator has apunched-paper tape output to facilitate data transmission to a com­puter for aero triangulation calculations.

photogrammetry and in the accuracy of thecalculations. Through point-to-point automat­ic dodging, electronic printers provide thesuperior contrast control that is particularlyimportant in aerial photos that are matched ingroups, such as mosaics and indexes. Theimproved detail that modulated electronicprinting provides in both highlight andshadow areas ofan aerial view leads to easier,more definitive photo interpretation in suchwork as volumetric calculations of stockpilesand full analytical aerotriangulation. Auto­mated data-handling equipment and thecomputer increase accuracy, of course, by re­ducing the potential effect of human error,especially in performing the same calcula­tions over and over again.

INCREASING PRODUCTIVITY

Two of the major pieces of equipment inthe Photo Lab are the Kodak Versamat

the processor and strip printer is substantial.In our experience, the combination of theLogE strip printer and automatic processorcompletes a roll of aerial flIm in about one­third the time of a conventional printer andhand processing. Compared with hand proc­essing and an electronic printer not equip­ped to handle rolls, the automated equip­ment processes a typical roll in about half thetime.

The LogEtronics SPlO170C strip printerexposes the paper through the film with ascanning spot on the face of a cathode raytube. The intensity of the scanning spot isautomatically modulated to increase the ex­posure in dense portions of the negative anddecrease the exposure in light portions. Un­iformly exposed, high-resolution prints canthen be produced in large volume from rollsof aerial negatives that vary widely in con­trast both between and within images. With aconventional fIxed-intensity printing light

INCREASING PRODUCTIVITY IN PHOTOGRAMMETRY 755

and hand developing, both exposure timeand developing ofthe paper would have to bevaried as the overall contrast level changesbetween images (contrast changes within animage, on the other hand, would requireeither multiple exposing lights or hand dodg­ing, both of which are too slow for quantitywork and usually unsatisfactory). With con­stant developing temperature and time in theautomatic processor, exposure of each paperimage must also be constant - a requirementthat, in high volume, can be practically ac­complished only with automatic contrast con­trol.

The usual procedure before film process­ing in an automatic processor is first to run astandard control strip through the processor,read the density of the developed strip, andadjust developer replenishment as neces­sary. A test strip is then run from the paperroll and, as a result, the developer re­plenishment rate is changed as called for.With the contrast control provided by theelectronic strip printer, however, the de­veloping time and temperature rarely need tobe changed from roll to roll.

The automated photo processing equip­ment also provides the capacity to completelarge projects rapidly, without impairingquality or overtaxing the lab facilities. Notlong ago, for example, a client requested thatfour areas approximately 200-300 squaremiles each be flown and that multiple photoreproductions be provided. Six contact printsof each negative and six copies of the photo

index for each of the four areas were to beprepared. As there were about 250 exposuresper area (scale of 1000 ft per inch), there weremore than 6,000 contact prints involved inthis assignment - and they had to be deliv­ered within seven days. Given the assign­ment on Friday evening, the four areas wereflown on Saturday (fortunately, the weatherwas good), and the order was delivered to theclient on the following Friday by air. Withoutautomated equipment in the Photo Lab, itwould have been almost impossible for acommercial organization to handle such anassignment within a week at a profitable andacceptable quality level.

IMPROVED QUALITY CONTROL

Film and glass positives for stereoplottingare exposed in an electronic contact printer toachieve better tonal balance within stereopairs. Inasmuch as the stereoplotter controlscan vary intensity but not contrast, unbal­anced pairs can make an already rather sensi­tive procedure far more difficult.

Diapositive film or glass plates are exposedin a LogEtronics Mark IV electronic contactprinter (Figure 2), which in 1973 replaced aMark II printer that the Photo Lab had usedfor seven years. The primary immediate ad­vantage of the newer model was that variabledodging provides the flexibility to get thebest possible results with different types ofexposures, which are encountered in stock­pile inventory work.

In addition, the Mark IV printer includes a

FIG. 2. Making a stockpile print on a LogEtronicsMark IV printer.

756 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1975

FIG. 3. Checking scale on plan-and-profile sheet on utilities map.

built-in capacity for extending electronicprinting from only black-and-white to coloras well. Although presently photography incolor alone costs about five times as much asin black-and-white, the photographic detailfor interpretation is far superior wherevervegetation is involved. Because color at pres­ent is now limited to special projects, filmand paper processing is done by an outsidefirm specializing in color. If volume grows tothe point where internal processing iseconomically feasible, a color cathode raytube will be installed in the Mark IV printer.

Contrast control is particularly important ifa number of prints are matched together inlaying mosaics or in preparing plan-and­profile sheets (Figure 3). Comprised ofa planphoto and a profile drawing, plan-and-profilesheets describe water, gas or sewer lines andother rights-of-way for engineering groups.The plan photo is usually made up of six toten contact prints layed in a strip mosaic,copied onto one negative and reproduced onphotosensitized polyester-base film byscreening to produce a halftone. Thescreened halftones and other line film aredeveloped in a DuPont Cronoflex ERF Proc­essor.

In property ownership mapping, it isnecessary to provide as part ofthe package 40x 40-inch enlargements of selected aerialnegatives. Normal proced\lre is to expose au­tomaticallya duplicate negative of the entireaerial roll in the electronic strip printer.Selected negatives in the automaticallydodged duplicate roll are then exposed in a

K&E 12x horizontal enlarger to make 5x en­larged paper prints. In this way, all the neces­sary contrast control is already provided inthe negatives so that uniform exposure of thepaper from enlargement to enlargement isassured.

In addition to the enlargements, photo­graphs in the property ownership mappingpackage includes one paper contact print ofeach aerial frame, a positive film halftone(lOO-line or 133-line screen) the same size aseach enlargement, and a photo index for eachscale of photography. In the present ongoingmapping project for Madison County (whereHuntsville is located), Atlantic AerialSurvey's Tax Mapping and Appraisal Divi­sions are mapping the country at four scales:50 ftJin for business, 100 ftJin for urban, 200ftJin for suburban, and 400 ft/in for rural sec­tions. The main element in the mapping pack­age is the base manuscript that recordsplanimetric features, grids, sections, town­ship and range lines, vegetation, and physicalfeatures.

STOCKPILE INVENTORY CALCULATIONS

Stockpile inventory calculations providevolume measurements of coal, gravel, sand,woodchips, logs and any other materials thatare stored outside in very large piles. A util­ity, for example, typically would need toknow the total volume of its coal piles fourtimes per year for its own inventory control,and annually for its auditors. The stockpile isflown to obtain a single good stereo pair ofphotographs, diapositive plates are made, and

INCREASING PRODUCTIVITY IN PHOTOGRAMMETRY

FIG. 4. Kern PG-2 stereoplotter, teletype terminal, digitizing unit consistingof Datos 303 Data Transfer System, DGC 400 Scaling Translator and a digitalreadout, all at one station.

757

the top profile ofthe stockpile is measured ona stereoplotter. At a compilation scale of 50ft/in an accuracy of plus or minus 1% per centof total volume can be guaranteed.

The primary equipment used in stockpilecalculations (Figure 4) is a Kern PG-2 Stereo­plotter, a Teletype terminal, and a digitizingunit (far left in Figure 4) consisting ofa Datos303 Data Transfer System, DGC 400 ScalingTranslator, and a digital readout, all in onechassis.

If the ground control has already been es­tablished (necessary, of course, only the firsttime that a particular stockpile is measured),the stereoplotter operator is able to detect thesurface of the stockpile at any point andmeasure its true position and height. Thevolume calculation uses the average-end­area method, which requires that theoperator follow the top profile of slices at thepile at regular intervals. Usual procedure isfor him to follow the stockpile profile at25-foot intervals in the X direction, makingreadings of the Z coordinate every 25 ft or atsignificant breaks (changes in profile) in theY direction. At each reading point, the digitiz­ing unit connected to the stereoplotter con­verts the X, Y and Z coordinates of its trueposition to digital form, which in turn ispunched on standard eight-channel papertape at the Teletype terminal.

After thus recording all reading points onthe surface of the stockpile, the punched tapeis entered into the Teletype terminal fortransmission to a time-sharing computer inDaytona Beach, Florida. Using a proprietarycomputer program called STOCKPILE, thevolume of each stockpile segment between

adjacent stations is determined by calculat­ing the cross-sectional area of each station,averaging the two end areas, and then multi­plying the average end area by theX-direction interval between stations, in thisinstance 25 ft. The calculations are then au­tomatically typed out in tabular formats in­cluding at the bottom a summation ofthe totalvolume of material in cubic feet.

In addition to measuring the top profile ofeach station of the stockpile, of course, calcu­lation of the end area requires knowledge ofthe bottom profile. In the preferable situationin which this information is supplied by theclient, the bottom profiles are entered intothe computer. This may be done either fromstation to station or the bottom profile en­tered at the end of the run. The simplest con­dition, of course, is if the stockpile is locatedon a flat surface (or nearly so) so that thebottom of each station can be considered astraight line.

The time required for stockpile calcula­tions naturally depends on the size of thepile. For the BIG CHIP PILE (Figure 5), atotal of 404 coordinates were read, a processwhich took about 45 minutes once thestereo pair was in position and digitizing unitset up. The three sets of calculations (BIGCHIP PILE, SMALL CHIP PILE, and COALPILE) took a total time ofabout 3% hours fromthe first reading to completion of volumeprintout on the Teletype terminal. Of thattime, about 30 minutes was involved in enter­ing the punched tape and receiving printoutsfor all three stockpile calculations.

The previous method for making stockpilecalculations was to read the coordinates,

758 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1975

draw the end area for each slice of the stock­pile, measure all the end areas with aplanimeter, and compute the total volumewith a desk calculator. The time required foreach of the three runs described above wouldhave been about 12 hours, so that the threetogether would have required nearly aman-week of time - 10 times as long as themethod using the digitizing unit and compu­ter. Although the largest proportion of thecost of a stockpile inventory is in airplanetime (even though there are only two expos­ures), automation of the calculation proce­dure has significantly reduced the total costof this service.

Considerable time is saved in reading thecoordinates by providing the stereoplotteroperator with contrast-controlled diapositiveplates exposed on the Mark IV ElectronicContact Printer. It is easier for the operator tolocate the surface of the stockpile at a givenZ-dimension in an automatically dodgedimage (top in Figure 5) than in an image that

is either too dark (such as with coal) or toolight (such as with gravel or sand) as in theundodged print of the same negative at thebottom. With variable dodging, the PhotoLab normally uses a high degree of dodgingfor gravel or sand and somewhat less dodgingfor coal. It is usually worthwhile to run a testprint with an estimated degree of dodging tobe sure of getting the optimum photographicdetail for the stereoplotter.

In our experience, it is possible to obtainthe same degree of accuracy in volumetriccalculations without a contrast-controlledstereo pair but it takes substantially longer tolocate the coordinates. Before using the elec­tronic contact printers, it was often necessaryto print two sets of positives for each stock­pile, one for the dark areas and one for thelight areas in the image. For an aerial view inwhich the quality of detail was not apparentuntil it was examined in the stereoplotter, itwas then necessary to make the stereo platesover again.

FIG. 5. Two contact prints of stockpiles made with a LogE Mark IV, dodged (upper) and notdodged (lower).

INCREASING PRODUCTIVITY IN PHOTOGRAMMETRY

FIG. 6. Wild PUG point transfer device, MK2 Kern monocomparator,Z-axis digitizer and Teletype with acoustic-coupler for computer connec­tion.

759

ANALYTICAL AEROTRIANG LATION

Another major area in which automatedphotographic printing and data handlingequipment have increased the productivity isin analytical aerotriangulation. Becauseaerotriangulation can reduce the cost ofground control as much as 75 per cent, in­vestment in the equipment shown in Figure6 can pay for itself quite rapidly. In Figure 6,the operator at the Wild PUG (at left) is pug-

ging film-positive plates for aerotriangula­tion used in analytical bridging. The KernMK2 Monocomparator (at right) is used tomeasure the distance between the PUGpoints that have been established (there areat least three and as many as eight points oneach plate). As with the stereoplotter in Fig­ure 4, the monocomparator output is automat­ically digitized, punched tape prepared andentered into the Teletype terminal for trans­mission to the remote computer.

Notice to Contributors

1. Manuscripts should be typed, double­spaced on 8l x 11 or 8 x 10! whitebond, on one side only. References,footnotes, captions-everything shouldbe double-spaced. Margins should beHinches.

2. Ordinarily (11/0 copies of the manu­script and two sets of illustrationsshould be submitted where the sec­ond set of illustrations need not -beprime quality; EXCEPT that fivecopies of papers on Remote Sensingand Photointerpretation are needed,all with prime quality illustrations tofacilitate the review process.

3. Each article should include an ab-

stract, which is a digest of the article.An abstract should be 100 to 150 wordsin length.

4. Tables should be designed to fit into awidth no more than five inches.

5. Illustrations should not be more thantwice the final print size: glossy printsof photos should be submitted. Letter­ing should be neat, and designed forthe reduction anticipated. Please in­clude a separate list of captions.

6. Formulas should be expressed assimply as possible, keeping in mindthe difficulties and limitations en­countered in setting type.