u ' If m5 HE'S. u ABSTRACT A HOLOGRAPHIC SOLUTION TO THE PROBLEM OF THREE-DIMENSIONAL DISPLAY IN THEMATIC CARTOGRAPHY By Robert H. McKay Thematic cartographers, over the last fifty years. have attempted to incorporate the use of the third di- mension in the product output of their field. Early attempts were inadequate by today's standards. owing to perceptual and portrayed dimensional inconsistancies. Subsequent development frequently failed to account for the needed realism expressed in terms of angular per- spective. The culminating factor attributed to the failure in attaining the goal of three-dimensional rep- resentation was the inability of the existant two- dimensional media to portray a true three-dimensional message. The development of holography has changed all of that. This technique offers the capability of present- ing a three-dimensional image on an essentially two- dimensional medium of expression. a piece of film or Robert H. McKay glass. Additional attractions. such as the ease of mea- surement and chronologically oriented multiplexing. can also be presented as definite advantages over conventional thematic cartographic techniques. The use of holography is the next step in the evolution of the cartographic field. The characteristics of holography demonstrated in this thesis prove that it is indeed a viable method for recording three-dimensional cartographic output on rela- tively conventional photographic film. A HOLOGRAPHIC SOLUTION TO THE PROBLEM OF THREE-DIMENSIONAL DISPLAY IN THEMATIC CARTOGRAPHY BY Robert N. McKay A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF ARTS Department of Geography 1975 ACKNOHLEDGMEMTS I should like to thank those that assisted in the development of this thesis: Dr. Dr. Dr. Dr. Dr. Dr. Mr. Gary Higgs, Committee Chairman Gary Cloud, MSU Dept. of MMM Dieter Brunnschweiler. Committee Member Robert Nittick, Committee Member Jack Hilliams. Committee Member Michael Chubb. MSU Dept. of Geography Lawrence H099. MSU Dept. of Geography ii TABLE OF CONTENTS Chapter I - The Problem Introduction Statement of Problem Objectives Hypotheses Definitions Data Sources Hypotheses Testing Graphic Representations Chapter II - The Historical Basis of Dimensional Perception and Display Early Man The Renaissance Early Cartographers Chapter III - Three-Dimensional Composition Axes Perspective Parallel Perspective Angular Perspective iii 10 10 ll 13 16 16 20 22 24 Chapter IV - “Three-Dimensional" Thematic Cartography Derivation from Topographic Mapping Dimensional Inconsistency Symbolism Perspective View Neglect in Landform Mapping Neglect in Thematic Computer Cartography Possibilities with Computer Mapping Induced Parallax Stereoscopic Models Inadequacies of Stereoscopic Drawings Basic Limitations of Standard Two-Dimensional Media Three-Dimensional Ends Using Three-Dimensional Means Three-Dimensional Perception .1 Problems with Models Chapter V - Holography Background Composition Elements Recording Reconstruction Production of Holograms Model iv 28 28 29 29 36 41 43 48 50 51 54 54 55 56 58 59 59 60 60 62 64 66 66 Instrumentation Operating Parameters Exposure Time Film Plate Processing Reconstruction of Holographic Image Procedure Photographic Limitations A Second Holographic "Set-Up“ Elements Photography Chapter VI - Findings of Qualitative Analysis of Holographically Reconstructed Images "Proof“ of Three-Dimensionality Advantages in Image Lacking Physical Existence Mensuration in All Three Dimensions Additional Advantages Nonexistent Limitations of Physical Presence Multiplexing of Scenes Chapter VII - Conclusion Continued Research Possibilities References Cited Appendix Bibliography 71 72 75 75 76 76 76 78 78 78 81 81 83 83 85 85 87 91 92 94 Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure IO 11 12 I3 14 15 16 I7 18 19 LIST OF FIGURES Analysis Process Two-Dimensional Axes More Common x-v-z Relationship Alternate X-V-Z Relationship Projections Perspective Views Raisz's Block-Pile Projection Planes Used by Raisz Zelinsky's Isometric Cube Projection Planes Used by Zelinsky Consistent Projection Planes Superimposed Projection Planes Total Isometric Perspective Parallel Perspective Isometric Perspective Two-Point Angular Perspective Stereogram: Corner View Stereogram: End View Coherent Light vii 18 19 21 23 26 32 34 35 37 38 39 4o 45 47 49 52 53 61 Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 21 22 23 24 25 26 27 29 31 Al Resultant Interference Pattern Holographic Recording Holographic Reconstruction Air Cushioned Holographic Hork Platform Holographic Recording Equipment Photographed Holographically Reconstructed Image Secondary Holographic Recording “Set-Up“ Photographic Evidence of Depth in a Holographically Reconstructed Image Photographically Multiplexed Holographically Reconstructed Image and a Steel Measuring Tape Photographically Multiplexed Holographically Reconstructed Image and an Engineer's Scale Midwestern U.S. Population in 1910 Midwestern U.S. Population in 1970 An Excerpt from Smith's 1920 Population Map of Ohio viii 63 65 67 73 74 77 79 82 84 86 88 89 Appendix CHAPTER I The Problem Introduction Off-axis holography is a technical process that can realize its result in a three-dimensional visual output of a three-dimensional diffuse object or scene. This process achieves this end by recording the interference pattern. resulting from the interaction of two coherent light wave- fronts (emitted from a laser light source), on a photographic plate. One of these wavefronts is a complex wavefront pro- duced by the reflectance of laser light off the physical components of a given diffuse object or scene. The other wavefront involved in this process is a plane wavefront that issues forth directly from the same light source. Hhile off-axis holography was originally applied to two-dimensional Graphic information, subsequent development of the technique has established the unique capability of three-dimensional display as its single greatest attribute. As do holographers. so too, thematic cartographers seek the graphical display of information. Since the 1920's 2 considerable attention has been paid to the portrayal of the third dimension by those of this field. Unfortunately, the three-dimensional limitations of the various media employed by thematic cartographers have negated any final realiza- tion of the three-dimensional objective. It would seem, then, that the ability of holographic means to display the third dimension could be augmented by the desires of thematic cartographers so anxious to achieve those same ends. The result of this union could be the birth of a true three-dimensional thematic cartography. Statement of Problem The problem to be investigated might initially be stated as, “Is this union possible?“ That is more of a technical question than the greater philosophical query of, “Should this union be made possible?“ Both eventually must be answered; with the former, perhaps, most legitimately being based only upon affirmation of the latter. To achieve this determination, the heritage of “three- dimensional“ thematic cartography must be examined. False assumptions, inconsistencies, and shortcomings of various methods used in contemporary “three-dimensional“ thematic cartography first must firmly be delineated. Hhile the suggested creation may rightfully be true three-dimensional thematic cartography, it must still prove itself viable in 3 a field that has been dominated since its genesis by two- dimensional graphics that utilized visual cues to gain the title (but not the body) of “three-dimensionality“. In this light, the importance of this thesis might be in terms of its search for truthfulness. The adoption of this technique could dispel the need for presenting illu- sions of three-dimensionality. If realism in any way sub- tends the “cartographic conscience“ then that alone should serve as raison d'etre for this conception. Objectives It is probably apparent that certain objectives of this thesis are couched within the previously broached questions. However, perhaps the ultimate goal of this work is to prove that three-dimensional thematic cartographic results can be achieved through the use of the essentially two-dimensional film plate used in the holographic process. flypgtheses I would first hypothesize that over the last fifty years thematic cartographers have been attempting to intro- duce and develop a concern for the portrayal of the third dimension. Secondly, these attempts. while coming closer t0 that goal with the passage of time, have not actually been able to portray the third dimension via two-dimensional 4 media. In conclusion, it is hypothesized that the use of the holographic process allows for the production of a three-dimensional thematic cartographic output on an essentially two-dimensional medium of expression. Definitions X-Axis Y-Axis Z-Axis Two-Dimensional “Three-Dimensional" Three-Dimensional Physical Model Holography Object Beam Reference Beam the first rectangular coordinate the second rectangular coordinate the third rectangular coordinate defined by x and y axes defined by x and y axes. but giving an illusion of the z-axis defined by the x, y, and z axes a three-dimensional structure, cartographic in nature, that is composed of statistical planes on the z-axis a recording and viewing process that allows reconstruction of three-dimensional images of diffuse objects or scenes a complex wavefront resulting from reflectance of a plane wavefront off a diffuse object or scene a plane wavefront emitted from the same source as the object beam 5 Hologram - the photographic record of the interference pattern resulting from object beam and reference beam interaction Off-Axis Holography - producing holograms by separate object beam and reference beam, offset at an angle to one another Data Sources The nature of this thesis does not call for the col- lection of quantitative data, so prevalent in contemporary geographic research. Rather, the comparative and contras- tive format of the investigation requires the use of quali- tative data. The products of differing variable viewing angle techniques will be examined in regard to their res- pective abilities to meet the objective of achieving “three- dimensional” (and ggtggl’three-dimensional) portrayal of thematic information. Owing to the static viewing angle of ninety degrees. “three-dimensional“ hill shading techniques. such as Tanaka's inclined contour method, Brassel's oblique hill shading method, and other variations on the same theme will not be analyzed in the context of this thesis. Several modes of representation will be applied to a common subject, total State populations of the midwestern United States. The techniques to be investigated are as follow: l) 2) 3) 6 two-dimensional base maps with volumetric symbols block diagrams physical models In addition to these methods of representation, a new technique will be applied to the thematic mapping problem. This technique is that of: 4) off-axis holography Data gathering will be accomplished by assembling and illustrating graphical products generated by the author. This output will consist of: I) 2) 3) 4) 5) 6) 7) 3) manually constructed drawings SYMVU computer plot outputs manually constructed physical model off-axis transmittance holograms of model multiplexed off-axis transmittance holograms of the model photographs of holographically reconstructed image of model photographs of multiplexed holographically reconstructed images of model in time sequence photographs of holographically reconstructed images of model photographically multiplexed with a physical mensuration device in reconstructed image plane IQKthheses Testing The testing of the hypotheses will consist of apply- i"£l the data to the qualitative analysis format illustrated 7 in Figure 1. The questions asked in the analysis are re- flective of greater awareness toward three-dimensionality as one progresses further through the process. Thus. the first hypothesis will be tested by noting at what point the various cartographic techniques respectively leave the questioning process. If the techniques are input according to the chronology of their development, and each successive input leaves the mainstream of the analysis at a greater level of penetration, the first hypothesis will be accepted. If all techniques. except the newly proposed method which utilizes off-axis holography, reach, "Conclusion: The product is not the optimal method for portraying three- dimensionality on a two-dimensional medium“, the second hypothesis will be accepted. If the newly proposed method that employs the off-axis holographic technique, reaches, "Conclusion: The product {1; the optimal method for portraying three-dimensionality on a two-dimensional medium“, the third hypothesis will be accepted. Graphic Presentations Presentation of "three-dimensional" graphics will be accomplished by standard two-dimensional cartographic tech- niques utilizing pen and ink. Computer generated graphics will be used to display the output from the SYMVU computer FIGURE l - ANALYSIS PROCESS N0 NO YES YES Conclusion: The product is not the optimal method for portraying three- dimensionality on a two- dimension medium. Conclusion: The product .13 the optimal method for portraying three- dimensionality on a two- dimensional medium. Input representation by various cartographic techniques. Is the product dimensionally consistent? Does the product exhibit parallel perspective? The product exhibits angular perspective. Does the product exhibit actual three-dimensionality? Does the product physically exist in three dimensions? Can mensuration be accomplished in all three dimensions? Do any additional disadvantages of the product void its use? Do additional advantages exist with the method or product? List those advantages. mappit Men: photo: image: recon image: entia' will \ natur- 9 mapping program. Photographs will be taken of all three- dimensional material relevant to the thesis. This includes photos of the model and the holographically reconstructed images. Since photography is a two-dimensional form of visual recording, the three-dimensionality of three-dimensional images will be compromised somewhat, by necessity. Differ- ential focusing, dependent upon photographic depth of field, will be submitted as “proof“ for the three-dimensional nature of the holographically reconstructed images. CHAPTER II The Historical Basis of Dimensional Perception and Display Early Man The first physical observance of depth undoubtedly occurred in the early pre-history of mankind. It was not a conscious observation, but a natural one. It was natural in the same terms as the perception of heat or pain. It was simply a small part of the "total man“. Man utilized his natural attention to depth in his daily regimen. It was this attribute of depth perception that allowed him to survive. His success at obtaining food depended directly upon the keen edge of distance judgment. So, too, did the success of avoiding physical harm from beast or other men depend upon this perception. As life continued, man found the desire to record his achievements. Recording took the form of graphical output upon cave walls. The meaningful highlights were rendered to future generations through pictorial accounts. These graphics attempted to portray life through the eyes of the beholder. lO ll Commitment to realism had a place in these illustra- tions, too. It may have been a chance occurrence that first prompted early man to apply color to these figures. but it was certainly not mere happenstance that promoted the con- sistent application of brown to the figures of creatures that were, in reality, brown in color. An additional aspect that relates to realism is that of the distance-size relationship. The cave dwellers might have first recognized this when noticing the apparent size of a creature from a distance. The closer the creature ventured, the greater its apparent size became. This real- ization, too, was incorporated in their drawings. In il- lustrating an assemblage of beasts. those that were a greater distance from the imaginary point of observation were drawn as smaller beasts. The Renaissance The Renaissance ushered forth an increased awareness of realism. Throughout the art-work of this time. fine atten- tion was paid to distance-size and angular relationships. Man was trying to illustrate via the essentially two- dimensional medium of brush and canvas the actual perceptions he obtained from his three-dimensional optical abilities. However, no amount of toil and tribulation could actually achieve these ends. The fact remained that at that time 12 there existed no method for utilizing two-dimensional means to achieve three-dimensional results. The use of distance- size and angular relationships worked toward giving all the visual cues that were associated with depth. but in no way could the elusive quality of realism be delivered. The Renaissance not only emphasized the importance of realism, but provided the technique and media necessary for the portrayal of depth. This was achieved by the many artists who made use of sculpting techniques. Frequently, these men were the same that used brush and canvas. It is rather difficult to determine which area of their talents most influenced the other, but one might theorize that the acute perception of depth so necessary for sculpting dra- matically influenced the perceptions rendered to canvas. In the case of sculpting, these people were presented with a medium that was entirely suitable for the presentation of three-dimensionality. The actual material used for the portrayal of sculpting is of little concern in the context of three-dimensionality. Hhether the finished product was stone or bronze, it was three-dimensional just the same. The unfortunate aspect of this artistic form was that the achievement of the three- dimensional quality had to be paid for by the price of existence in physical space.- As opposed to a painting of 13 the Last Supper. a sculpture would have achieved depth at the cost of obfiscating the usefulness of that portion of the room in which the sculpture was situated. Early Cartographers There is no doubt that the actual origins of carto- graphy go back to the first person who traced his path, the location of animals, or the course of a river in the sand with a stick. However, cartographers of the western world generally seem to trace the pragmatic foundation of their discipline to the fifteenth century. It was during this period that man sought the need to record his location relative to the larger geographical area of his concern. By the Age of Discovery, this area of concern had ex- tended to well beyond the horizon. It was no longer feasible to portray all essential information to an assoc- iate by means of a few crude line-drawings in the sand. Furthermore, there arose the need to take this information away from the point of original composition to other locals. The realm of the world was expanding rapidly. The services of cartographers were employed to meet this chal- lenge, primarily through the production of portolani and other forms of nautical charts. The world trade routes were developing upon the oceans. The guidance of vessels 14 over these unknown surfaces to their ports-of—call became a paramount concern to many. including the cartographers. It is significant to note that the fundamental under- pinnings of this field had not changed one iota from the time when cave dwellers drew lines in the sand. The in- tegral importance of man, land, and water had been carried- on throughout the evolution of mankind. However, so too, another fundamental aspect did carry through from time immemorial . . . . the recording of the man-land-water significance upon a two-dimensional medium. It is easy to see why nautical charts developed to indicate only the x and y axes. Since the water bodies travelled were perceived as planar surfaces, there was no need to portray a z-axis. All necessary information could be shown to relate only to that plane. Even the three- dimensional qualities of shoals and reefs had little im- portance to the seafarers other than the fact of their location upon that two-dimensional perceptual plane. The point being made is that the eventual development of the two-dimensional Cartesian Coordinate System in the seventeenth century by DesCartes was a very systematic and predictive occurrence. Given the fact that the direction of travel and relative location were viewed in planar terms, it is quite logical to assume that any representation of 15 the same would be viewed in similar terms. The importance of the Cartesian Coordinate System is most pointed in its direct and meaningful applicability to the representation of the situation from which it had been derived. Eventually, this planar view of the earth changed. Perhaps it was due to exploration inland from the seacoasts. In any case, as man traversed the land surface, cartographers were required to include new types of information to the products of their trade. If mountains were found at a cer- tain location, it became the responsibility of the carto- graphers to portray this aspect. A form of crude symbol- ization was first adopted to achieve this representation, but in no way did it even come close to anything that could be deemed realistic. Inappropriately, instead of developing a method from the newly existent situation. cartographers manipulated the situation to fit their existing method. Nautical charts assumed a constant plane and the subsequent necessity of portraying only the x and y axes upon that plane. The addi- tion of landforms or other three-dimensional items, while obligating consideration. did not receive consideration for the portrayal of that heretofore unrecorded dimension, the z-axis. CHAPTER III Three-Dimensional Composition Ages The Cartesian Coordinate System was originally deve10p- ed from the mathematical modeling of Rene DesCartes in the seventeenth century. While some contemporary cartographers might scoff at the need for definition of this system, it is necessary in the context of this thesis. ”Cartesian Coordinate System -- l) A two-dimensional coordinate system in which the coordinates of a point are its distances from two intersecting, often perpendicular straight lines, the distance from each being measured along a straight line parallel to the other. 2) A three- dimensional coordinate system in which the coordinates of a point are its distances from each of three intersecting. often mutually perpendicular, planes along lines parallel to the intersection of the other two."' It is clear that both denotative meanings are derived from a common philosophical vantage. However, in practice, the connotative meanings accepted by many cartographers are 16 17 derived from the realm of their experiences. This is to say that those cartographers whose experience has been pre- dominantly confined to two-dimensional work will find it difficult to think in terms of a three-dimensional context. For that reason. these relationships will be examined. Owing to the first definition, two axes must be de- fined. Those are the abcissa and the ordinate. The abcissa is the x-axis, the first rectangular coordinate”; that mea- sured on the horizontal axis. The ordinate is the y-axis. the second rectangular coordinate'; that measured on the vertical axis. The relationship of these axes is shown graphically in Figure 2. The representation is functionally planar and therefore ideally suited for the two-dimensional character of a pen and ink drawing. The three-dimensional definition introduces a third coordinate. This is the zenith -- the z-axis. the third rectangular coordinate'. The standard graphic mathematical portrayal of the x, y. and z axes' interrelationship is shown in Figure 3A. The '0' indicates the origin in this right-handed coordinate system. The dashed line indicates that the axis is extending out of the page toward the viewer. This imaginary three-dimensional figure could be “laid on its back“ without destroying the relationship of the 18 . w_x< .._<._.ZON_mOI .fi. u N $50.... 19 $7629.2me Ni>ax 20.2200 mac—2 .. m manor... \x 20 axial planes. If this were done, the illustrated version would appear as in Figure 3B. The z-axis should be imagin- ed extending back through the page. Applying this relation- ship to a cubical structure would result in the portrayal shown in Figure 3C. Broken lines are utilized on the far side of the cube in an attempt to minimize the possibility of optical illusion. Hhile Figure 3 illustrates the more common x-y-z re- lationship, another visual portrayal is also acceptable.5 This is shown in Figure 4A. Figures 48 and 4C have re- ceived the same relative adjustments in their visual rep- resentations as did Figures 38 and 3C. The purpose of pointing out these differing modes of x-y-z relationship is not to confuse the reader. It is merely to set the stage for continued discussion. He will find that thematic cartographers have utilized both of these representations in their art. Consequently, a working base of common understanding must be established at this time. Perspective Simply stated, perspective is the way in which we see an object dependent upon the viewing point. the elevation of that point above the horizon, and the azimuth on the horizon.‘ Perspective is utilized significantly for carto- graphic purposes in the attempt to provide a mapping 21 \ n=Imzo_._.<._um Nnrux w>_._.m 0mm: mmz<4m zo_._.omq.omn_ I m mmaoE 35 FIGURE 9 - ZELINSKY'S ISOMETRIC CUBE I V (I L 36 exists. However, consistency could have been realized by Zelinsky had he adjusted either the projection plane of the base map or the projection plane of the imaginary base upon which the isometric cubes rest. By adjusting the former to fit the latter, the product as shown in Figure 11 can be derived. The cross-sectional diagram of this derivation, Figure 12, illustrates that the two planes in question are super- imposed on one another. Furthermore, dimensional consistency can be achieved by utilizing the isometric symbolism com- bined with an isometric projection of the base map. Hhile Figure 11 is consistent in terms of the projection planes, true dimensional consistency can be gained by incorporating a form of total isometric perspective that would view the scene from the southeast and appear as in Figure 13. Perspective View While the cartographic examples, both reproduced and newly generated, have shown an increase toward a greater appearance of “three-dimensionality”, it may be noticed that they are all deficient in terms of angular perspective. This is not too difficult to believe when we realize that angular perspective has been essentially disregarded by thematic cartographers throughout the field, from past to present. This point is substantiated by the conspicuous 37 _—_-—|_.__.__———_- kmmm mmmao . QEMSOm. 1213 20m: mwm cum: mmz_._.0mmmmwn_ 04.5024 0.2.9703... I 0. mane—u— 50 perspective has fostered the development of an additional problem . . . . mensuration. It may be noticed in Figure 20 that a scale has been computed and displayed. However, we must realize that the scale portrayed in this sense is virtually meaningless. Since we have empirically determined that the apparent z-axis scale is variable in relation to changes in the x and y axes, any scale used to measure this z-axis must be variable in that respect, as well. Needless to say, that is an awkward problem for a situation such as that presented. If the “three- dimensional“ map was truly three-dimensional in a physical sense, we could achieve these measurement objectives. Unforutnately, since the presentation is limited to two dimensions, we have no way to thrust any type of device “back“ into the portray 1. Hithout a variable two- dimensional mensuration device, we cannot actually deter- mine the quantitative difference between portion of the map such as Michigan and Illinois. Induced Parallax Through the use of parallax, it might be assumed that the two-dimensional limitations of pen and ink might be overcome. Several systems could be applied to the situa- tion as possible solutions. These include the familiar 51 blue and red lensed glasses, the horizontally and verti- cally oriented Poloroid lensed glasses, or the stereoscOpe. All work on the same fundamental principle of each eye viewing the same scene from a slightly different angle. Hence, by constructing a drawing that makes use of in- ducing parallax and placing it next to the original symbol, a stereopair has been formulated. Quite importantly, the viewing point displacement must be determined to be on the linear axis of the viewer's eyes. Stereoscopic Models Figure 17, when viewed with a pocket stereoscope, can be used to demonstrate induced parallax in two stereomodels featuring corner views. Figure 17A is an isometric cube, while Figure 178 is a cube in two-point perspective. The inpropriety of the isometric cube as a three-dimensional symbol becomes readily apparent when parallax is induced and a stereoscope is used for viewing. Thus, the importance of two-point perspective in a corner view is extremely sig- nificant if the goal of a realistic portrayal is to be attained. Figure 18 provides a similar stereomodeled contrast between the ”block-pile“ utilized by Raisz (Figure 18A) and a similar structure modified in a manner to account for one-point perspective (Figure 188). Again, that 52 w>_._.omn_mmwa ._.z_on_I03._. .0 wmao 0.0.5200. .4 3m; mmzmoo .24moommmkm I h. manor. I) ) 53 m>_._.0mn_mmwn_ ._.z_on_Imzo .0 50.5 m.~m_