The Power of the Image: Non-Photorealistic Rendering (AFF-622)

The Aesthetics of Stylisation

This blog entry is the second in a series of posts dealing with the Power of the Image, more specifically on the use of non-realistic rendering in Digital Heritage. In my last post I dealt with the concept of photorealism in Digital Heritage; specifically how we approach and interpret this idea and apply it to digital methodologies, whatever they may be. It stands to reason then that the opposite end of the spectrum should be explored.

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We saw previously that the aim of photorealistic rendering is to capture and represent an object as closely as possible to the original. This allows these representations to be immeasurably useful in the fields of digital and cultural preservation, specifically in recording minute physical aspects of artifacts, monuments, and cultural sites. Sometimes, however, it seems that we require, whether through artistic aims or from technical constraint, to represent data or a model in a stylised manner. This can often be a less time consuming method of recording and presenting data. It is through this need or requirement, or lack thereof, that we employ the use of non-photorealistic rendering (which will henceforth be abbreviated as NPR).

Simulation vs. Illusion

The application of stylisation lends itself to the idea that in some cases it should not be the all-encompassing goal of a creator to strive for extreme detail, but rather to aim for the flexibility that can be achieved through stylisation. Anna Vilanova asserts that

“…simulating reality is not as important as creating the illusion of reality in the eye of the beholder”

NPR can help give us renderings that would often mirror an artist’s representations using software that can recognise image silhouettes, frames, or dimensions and construct a non-photorealistic 3D or 2D model for us. These applications could have use within a wide spectrum of disciplines, from archaeology to architecture to interior design.

Within the perspective of Digital Heritage, however,  let us take for example a case wherein an archaeologist wants to create a non-photorealistic reconstruction of a site from archaeological findings. Specifically, I refer to Tom Frankland’s example of a crannóg in Thinking Beyond the Tool. Here, we can see that through the use of pre-existing data and the use of Google SketchUp and several plugins, both a 3D and 2D NPR model can be created. The use of NPR software in this case is invaluable for its reduction of time and labour for an archaeologist.

The visual aesthetics of NPR can also be quite appealing to  just about any user, even from a purely cosmetic standpoint. We can use software such as Adobe Photoshop to add filters to our images to create an image that looks as if it was painted in an expressionistic or impressionistic style, ultimately ‘converting’ a photorealistic image into a non-photorealistic one. Furthering this even more, there are practically dozens of smart-phone applications that can achieve the desired effect.

User Interactivity and NPR

In my previous post, I looked at the idea of immersion with regard to user interaction. User interactivity can extend a project beyond simply preservation and is possibly the cornerstone to any project that aims to present the user with a satisfactory experience, undoubtedly with regard to education. As computer game development continues to expand as a medium, there are techniques through which we can create immersive user experiences that incorporate elements of Digital Heritage and combine them with the artistic flexibility and accessibility of NPR.

Non-photorealistic techniques can create environments similar to cartoons through the use of 2D cel-shading, which allows for faster development of the game but can also give the game its own artistic flair. Cel-shading is achieved by emphasising strong line and colour in such a way that there is a greater definition between light and dark, evoking a stylised cartoonish quality. The ease of this technique can allow the creators more time to tell the story they want and not have to focus as entirely on exact detail. A great example of this is Valiant Hearts: The Great War, which uses a highly NPR art style and even presents the user with photorealistic images of artifacts from the First World War. The cel-shaded graphics allow the game to remain PG without detracting from the bleak and poignant story and subject matter. In a way, the art-style only serves to heighten this poignancy for the user. Through the use of this medium we can present concepts of Digital and/or Cultural Heritage to users in an accessible way that really shows off the benefits of NPR.

Summary

Through this blog it has been asserted that for every task that we are presented with in the field of Digital Heritage, there are many ways through which we can achieve our aims on a presentational level. Photorealistic and non-photorealistic renderings equally have their place with regard to the recording and representation of data, and often it is the case that both may be used. It is a combination of presentation and immersion that determines whether or not a user can garner anything useful from a project. An archaeologist or creator’s choice of presentational aesthetic can make or break a project’s usefulness. Overall, this blog establishes that NPR is the more flexible and malleable rendering methodology with regard to the image, perhaps lending itself more to artistically creative representation than acute reproduction.

Bibliography 

Benjamin, W. 1936 (1968). “The Work of Art in the Age of Mechanical Reproduction.“ Illuminations, 217-51. New York: Schocken Books.

Drettkis, George, Roussou, Maria, Photorealism and Non-Photorealism in Virtual Heritage Representation, First Eurographics Workshop on Graphics and Cultural Heritage (2003), 2003, Brighton, United Kingdom. Web, accessed 10/10/15.

Frankland, Tom, ‘A CG Artist’s Impression: Depicting Virtual Reconstructions Using Non-photorealistic Rendering’, Thinking beyond the Tool Archaeological computing and the interpretive process, pg 38-42,  Chrysanthi, A., Murrieta Flores, P., Papadopoulos, C. (eds) 2012 BAR International Series 2344.

Hanratty, Conor, Adaptive Abstraction using Non-Photorealistic Rendering in XNA, Web, accessed on 20/10/15.

Hertzmann, Aaron, Introduction to 3D Non-Photorealistic Rendering: Silhouettes and Outlines, Media Research Laboratory, New York, Web, accessed 21/10/15.

Kang, Hang-Bong, Kwon, Yong-Moo, The Needs and Possibilities of Nonphotorealistic Rendering for Virtual Heritage, Imaging Media Research Center, Korea Institute of Science & Technology, Web, accessed 20/10/15.

Ubisoft Montpellier, Valiant Hearts: The Great War, Ubisoft, 2014.

Vilanova, Anna, Non-Photorealistic Rendering, Web, accessed 20/10/15.

 

 

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rbreen

MA Digital Humanities student in An Foras Feasa, Maynooth University. BA Music from Maynooth University.

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