Non photorealistic rendering (NPR) is a well tested area as it has its origins in the field of art history and practice. What is new however are NPR computer rendering techniques to make new types of images. This post will explore NPR history as well as the uses of NPR to create new useful types of images in cartography, archaeology, science and medicine and the search for the creation of new meaning and knowledge.
NPR, as an area of research, began in the early 1990’s. Computer graphics research was being published in journals by interest groups in fields such as electrical engineering and computer graphics. The Special Interest Group for Computer Graphics (SIGGRAPH) conference began sessions on research in NPR around this time, followed by the first fully dedicated symposium in 2000 (Strothotte and Schlechtweg, xvii).
2. Non-photos and Non-realism:
In the present day, every ‘style’ of visual representation is at a person’s disposal. NPR is often a style chosen; not because photorealism isn’t accurate but because in some specific cases, which will be discussed in this blog post, photorealism might not be as useful as NPR. Photorealistic images could be described as ‘complete’ and can fail to convey information as clearly as an NPR image(Strothotte and Schlechtweg, 6).
When realism is no longer a goal, other compositional, representational and symbolic factors can come into focus. In Egyptian art, what is depicted does not represent what we could see with our eyes, the human figure is distorted (face and legs are in profile whilst the torso is full frontal). At the same time the borders of these images are filled with hieroglyphs and sometimes animals from nature; represented almost photo realistically and anatomically correct (Fig.1). The purpose of these images isn’t one of accurate representation, instead its aim could be seen as one of high spiritualism through the choice of symbolism and abstraction. Similarly, Picasso’s “Guernica” can be interpreted to have a similar goal, it is said that it acts as a magnifier of emotion and for some, it acts as a symbol representing the whole of the Spanish Civil War (Fig.2).
3. On Mapping:
Kenelley and Kimerling outline how NPR ‘looks at techniques designed to achieve other ends’ in their specialist field; terrain representation in cartography(35-51).
Acknowledging that even when a realistic map could be produced for the presentation of the topography of any landscape, some pre-computer NPR ‘renderings remain much revered and often cited.’
In their book, Strothotte and Schlechtweg describe the virtues of drawing by hand; “it is possible to free oneself from physical constraints of reality and to convey an impression rather than just to convey details of a scene’s appearance(4).’ According to Kenelley and Kimerling this would include cartographic generalization, the possible deformations of images and map projections (36).They also mention in particular physiographic diagrams (Fig.3a) as ‘unique stylised renderings’(51; Strothotte and Schlechtweg, 4 ). This (now computer generated)NPR style of illustration includes what could be familiar as the isometric tourist city map.Digital cartography is making efforts to blend what was great about hand drawn maps with digital rendering technology with the use of NPR techniques (Fig.3b).
4. Science and Medicine:
Strothotte, Schlechtweg and Gooding also look at medical and scientific illustration as fields that benefit from using NPR (25; para 53). Gooding outlines how a ‘common feature of all scientific method is managing complexity‘ as ‘not everything is of equal importance all of the time’( para 47). Scientific illustrations are used as a tool to visualise and communicate single or multiple hypotheses at important intervals in the scientific process and therefore ‘illustrating in science is about illustrating process’ (para 53). Strothotte and Schlechtweg discuss how medical illustrations, show how it is sometimes necessary to change the appearance of the object represented to increase clarity. Certain medical illustration conventions apply: Veins are shown as red or blue, ligaments are white and muscles brown. Sometimes an exaggeration of scale is used to show detail of a particular area. ‘Sometimes an organ may be rotated somewhat relative to the other parts simultaneously to provide a better view on all objects in a single image and to be able to study several objects in the context of one another (15). (Fig.5) Whilst some details are highlighted others are left deliberately vague depending on the aim of the illustration. This method is often used for emphasis and clarity in illustrations used for industrial design, user manuals (Gooch and Gooch, 1) (Fig.6), architects sketches (as outlined in BP1) and in archaeological NPR also.
5. The Artists Impression:
The archaeological illustrator is sometimes described as the ‘first spectator within the environment of information’ on an archaeological site (Wollheim, 101-2 qtd. in Molyneaux, 1).
Even with the introduction of photography, the hand-drawn illustration of sites and finds has remained part of archaeological fieldwork(Fig.7). As for the creation of artistic impressions or photorealistic ‘reconstructions’ of how a site may have looked; the evidence for what every part of a site looked like might not exist (as illustrated by the multiple renderings of the Athenian gates in Eiteljorg’s article (5). Bateman suggests that trying to align our texts and images together is an impossible and false goal (5). A single photorealistic image may look “believable” and still be unable to show the level of detail that exists in the accompanying texts (Bateman, 5; Roussou et al, 1). Roussou et al go further to say that the use of NPR’s might be preferable to photorealistic images ‘to underline the fact that we are not dealing with indisputable facts’(8). In their 2003 article, they outline how a ‘perception of realism’ could be achieved through Photorealism and or NPR with the addition of interactivity (abstract).
In reference to interactivity; Eric Champion is cited in Rahaman et al proposing that an end-users engagement with interactive cultural heritage depends only in part on graphic realism(3). Taking into account his experience in computer gaming theory, he is cited as suggesting that static graphic realism is more suited to non-interactive applications and therefore, in his opinion, not computer game environments (Ibid).
6. Group Surveys:
Both Strothotte, Schlechtweg and Frankland conducted surveys on the uses of Photorealistic and NPR images (see BP1 for Frankland) (313; 26-27). In 1995, Strothotte and Schlechtweg surveyed 54 architects and architecture students on the uses of 3 types of NPR visualisations (sketch, 3D shaded and exact plot). As well as measuring their types of responses to these images they, like Frankland in 2012, also surveyed their group about which image was considered suitable for what purpose. In the 1995 survey 53% chose the NPR sketch image as a way to present a first draft and the exact plot (NPR) for the presentation of a final design.
Frankland’s survey group results seem similar to Strothotte and Schlechtweg’s architects in that they also chose images, in response to survey questions, to fit specific purposes.
7. 3D Laser Scanning:
Whether it could be defined as NPR imagery or not; the use of 3D laser scans taken on archaeological sites, to produce qualitatively rendered models, could possibly allow archaeologists and the public to learn more by recording every stage in the on-site archaeological process(Forte, 3). The overarching idea of being able to make archaeology ‘reversible’ is a very attractive one. The work Forte describes on site in Çatalhöyük is getting close to Strothotte and Schlechtweg’s goal of ‘adding value’ to 2D and 3D imagery through its experiments with interactivity(10)(Fig.8).
It remains to be seen if new NPR techniques such as the laser scans used in Çatalhöyük can allow archaeologists and the public to learn more by recording every stage in the archaeological on-site process (Fig. 9). The great strength of NPR is as a tool to communicate knowledge and convey information (Foley et al. cited in Strothotte and Schlechtweg, 308; Gooch and Gooch, 2). In Cartography, advances in NPR graphics of real world data are creating a blend of meaning making, accuracy and aesthetics. We have also seen how it can be used to record and visually illustrate process and uncertainty with architectural sketches, scientific illustrations and laser scans (Strothotte and Schlechtweg, 317-318). A photorealistic image can convey a vast array of information but a non-photrealistic is the ‘toolkit’ to communicate ideas.
List of Figures
Fig. 1 – “Nebamun hunting in the marshes”, fragment from tomb of Nebamun,Thebes, Egypt. circa 1350 B.C. Source: https://www.britishmuseum.org/explore/highlights/highlight_objects/aes/n/nebamun_hunting_in_the_marshes.aspx
Fig. 2 – “Guernica” by Pablo Picasso.1937. 3.5m x 7.8m. Museo Renia Sofia, Madrid.
Fig. 3a – “Physiographic Diagram of the Seven Devils Mountains” by Tau Rho Alpha and William A. Austin. 1982. Web 22 Oct 2015. Source: Google Images
Fig. 3b – “Digital map with manual shading” by Eduard Imhof and Canton Grisons Web 23Oct 2015. Source: http://cartography.oregonstate.edu/TerrainShadingAndColoring.html
Digitally shaded relief is […] not as successful at portraying terrain as manually produced shaded relief images
Fig. 5 – Example of a hand drawn medical illustration taken from a textbook on anatomy. Source: “Non-Photorealistic Computer Graphics” by Strothotte + Schlectweg p25
Fig. 6 – “Upper Threading”. Singer Sewing Machine Model 327K- Users Manual p12.
Source: A. Holland
Fig.7 – Stipple drawing of an Acheulian flint handaxe in Andover Museum (1963.31).
Fig. 8 – Enhancement of a medical image through edge detection and visualization. An
original medical image is exaggerated using edge enhancement software has
determined where discontinuities in the surface exist, and these are shown in the NPR
Source: “Non-photorealistic Computer Graphics” by Strothotte and Schlechtweg,2002. p19
Fig. 9 – Teleimersive session with a Wii: Showing Building 77, 3D model of GIS layers. 2011.
Source: Article, 3D Archaeology at Çatalhöyük by Forte et al. on Academia.eu
Bateman, J. 2000. “Immediate Realities: An Anthropology of Computer Visualisation in Archaeology.” Internet Archaeology 8 .Web 7 Oct 2015 http://dx.doi.org/10.11141/ia.8.6
Gooding, D., C. “Envisioning Explanation: The Art in Science” Chapter1 of Frischer, B. and Dakouri-Hild, A. 2008. Beyond Illustration: 2D and 3D Digital Technologies as Tools for Discovery in Archaeology. BAR Series 1805. Archaeopress.
Eiteljorg, H. 2000. ”The Compelling Computer Image – A Double-Edged Sword.” Internet Archaeology 8. Web 7 Oct 2015. http://intarch.ac.uk/journal/issue8/eiteljorg_toc.html
Forte, M., Dell’Unto, N., Issavi, J., Onsurez, L., Lercari, N. 2012. “3D Archaeology at Çatalhöyük.” Web 11 Oct 2015. https://www.academia.edu/2205617/3D_Archaeology_at_Catalhoyuk
Frankland, T. 2012. “A CG Artists Impression: Depicting Virtual Reconstructions Using Non-photorealistic Rendering Techniques.” Chapter 2 in Thinking beyond the Tool Archaeological computing and the interpretive process, Chrysanthi, A., Murrieta Flores, P., Papadopoulos, C. (eds) 2012 BAR International Series 2344.
Gooch, A., A. 2010. “Towards mapping the field of non-photorealistic rendering.” In Proceedings of the 8th International Symposium on Non-Photorealistic Animation and Rendering (NPAR ’10). ACM, New York, NY, USA, 159-164. DOI=http://dx.doi.org/10.1145/1809939.1809958
Gooch, B and Gooch, A. A. “Non-Photorealistic Rendering.” AK-Peters, 2001. Web 21 Oct. 2015
some pages of intro of book on: http://www.amazon.com/Non-Photorealistic-Rendering-Bruce-Gooch/dp/1568811330
Kennelly, P.,J and Kimerling, A.,J. 2006.“Non-Photorealistic Rendering and Terrain Representation”. Web 20 Oct. 2015 http://www.cartographicperspectives.org/index.php/journal/article/viewFile/cp54-kennelly-kimerling/405
Molyneaux, B.L. (ed.) 1997 ”The Cultural Life of Images: Visual Representation in Archaeology.” London and New York: Routledge. Web 10 Oct. 2015
Rahaman, H. and Tan, B-K. 2010” Interpreting Digital Heritage Considering the End-user’s Perspective.” Web 8 Oct 2015
Rahaman, H., Das, R. and Zahir, S. 2012. “Virtual Heritage: Exploring Photorealism.” Web 8 Oct 2015. Web 11 Oct 2015
Strothotte, T. and Schlechtweg, S. 2002. “Non-Photorealistic Computer Graphics: Modeling, Rendering, and Animation.” Elsevier, Morgan-Kaufmann series in Computer Graphics. 01 Jan 2002. Web 21 Oct. 2015.