Developing Generalized Cross Hatching Shader Approach for Non-Photorealistic Rendering

In this research, I present a method for rendering a geometric scene that has the look and feel of artistic hand drawings, particularly using a medium such as charcoal or crosshatching. While there have been many approaches to non-photorealistic (NPR) renderings in the past two decades, there seems to be very little research done on how to obtain such charcoal or cross-hatching effects, especially with attention to reflections and specularity, which often at times seems to break the illusion of the drawing effect. I developed a new class of techniques, using a Barycentric shading method, that allows the non-photorealistic rendering of a variety of artistic drawing styles. My approach can be summarized as follows: (1) a Barycentric shader that can provide generalized crosshatching with opaque multi-textures, (2) a Barycentric shader using transparent multitextures, and (3) a texture synthesis method that can automatically produce crosshatching textures from any given image

Developing Generalized Cross Hatching Shader Approach for Non-Photorealistic Rendering

In this research, I present a method for rendering a geometric scene that has the look and feel of artistic hand drawings, particularly using a medium such as charcoal or crosshatching. While there have been many approaches to non-photorealistic (NPR) renderings in the past two decades, there seems to be very little research done on how to obtain such charcoal or cross-hatching effects, especially with attention to reflections and specularity, which often at times seems to break the illusion of the drawing effect. I developed a new class of techniques, using a Barycentric shading method, that allows the non-photorealistic rendering of a variety of artistic drawing styles. My approach can be summarized as follows: (1) a Barycentric shader that can provide generalized crosshatching with opaque multi-textures, (2) a Barycentric shader using transparent multitextures, and (3) a texture synthesis method that can automatically produce crosshatching textures from any given image

A Process to Create Dynamic Landscape Paintings Using Barycentric Shading with Control Paintings

In this work, we present a process that uses a Barycentric shading method to create dynamic landscape paintings that change based on the time of day. Our process allows for the creation of dynamic paintings for any time of the day using simply a limited number of control paintings. To create a proof of concept, we have used landscape paintings of Edgar Payne, one of the leading landscape painters of the American West. His specific style of painting that blends Impressionism with the style of other painters of the AmericanWest is particularly appropriate for the demonstration of the power of our Barycentric shading method

A Process to Create Dynamic Landscape Paintings Using Barycentric Shading with Control Paintings

In this work, we present a process that uses a Barycentric shading method to create dynamic landscape paintings that change based on the time of day. Our process allows for the creation of dynamic paintings for any time of the day using simply a limited number of control paintings. To create a proof of concept, we have used landscape paintings of Edgar Payne, one of the leading landscape painters of the American West. His specific style of painting that blends Impressionism with the style of other painters of the AmericanWest is particularly appropriate for the demonstration of the power of our Barycentric shading method

Art Directed Watercolor Shader for Non-photorealistic Rendering with a Focus on Reflections

In this research, I demonstrated that emulating painterly reflections is impossible using existing modeling, compositing and rendering software that does not provide programming capabilities. To obtain painterly reflections, we need to emulate three aspects of painterly reflections: (1) shape of reflections; (2) glossiness of reflections; and (3) colors of reflections. The first two turn out to be relatively easy. However, despite the perceived simplicity of color reproduction, the third one turned out to be hardest without developing our own proprietary tools. To demonstrate the difficulty, I have developed a shader using commercial rendering and shading software that does not provide explicit programming power. I assigned my shader as a surface material to 3D objects. Using my shader, I was able to create computer generated watercolor style renderings without reflections. My shader provide rendering effects such as diffuse, contours, specularity, shadow, and reflections. Although I can faithfully emulate non-reflected regions of given water-color paintings, I demonstrate that my shader cannot produce reflection colors that are faithful to colors of original reflections

Web-Based Dynamic Paintings: Real-Time Interactive Artworks in Web Using a 2.5D Pipeline

In this work, we present a 2.5D pipeline approach to creating dynamic paintings that can be re-rendered interactively in real-time on the Web. Using this 2.5D approach, any existing simple painting such as portraits can be turned into an interactive dynamic web-based artwork. Our interactive system provides most global illumination effects such as reflection, refraction, shadow, and subsurface scattering by processing images. In our system, the scene is defined only by a set of images. These include (1) a shape image, (2) two diffuse images, (3) a background image, (4) one foreground image, and (5) one transparency image. A shape image is either a normal map or a height. Two diffuse images are usually hand-painted. They are interpolated using illumination information. The transparency image is used to define the transparent and reflective regions that can reflect the foreground image and refract the background image, both of which are also hand-drawn. This framework, which mainly uses hand-drawn images, provides qualitatively convincing painterly global illumination effects such as reflection and refraction. We also include parameters to provide additional artistic controls. For instance, using our piecewise linear Fresnel function, it is possible to control the ratio of reflection and refraction. This system is the result of a long line of research contributions. On the other hand, the art-directed Fresnel function that provides physically plausible compositing of reflection and refraction with artistic control is completely new. Art-directed warping equations that provide qualitatively convincing refraction and reflection effects with linearized artistic control are also new. You can try our web-based system for interactive dynamic real-time paintings at http://mock3d.tamu.edu/.Comment: 22 page

Developing Generalized Volume Sampling and Volume Shading for Non-Photorealistic Rendering

This paper presents a methodology for sampling and rendering 3-dimensional (3D) volume data to give it the appearance of classical ink-and-paint techniques. Although tremendous strides have been made in the realm of realistic volume rendering, research on rendering techniques for non-photorealistic (NPR) images is limited and does not yield results that provides artists the ability to create and render volumes in a classical animation style. Currently, the industry standard is to render the volume using 3D volume data and the diffuse channel, or to provide a card and play an image sequence on the card. This paper discusses a technique that allows for the non-photorealistic rendering of 3D volume data which can be used to sample and shade a variety of shapes to create a stylized render of a volume, similar to classical ink-and-paint techniques. This approach can be summarized in the following steps: (1) Scatter point data within 3D volume data based off of density values, or create a custom point cloud; (2) Ray cast from the camera to the hit position of the volume; (3) From the hit position of the ray, cast towards a direction (either towards a light for shading, or continue in the same direction for a headlamp effect); and (4) Tally and normalize the number of scattered points within a radius of the direction of said ray; then (5) Use this value to interpolate between the lit color of the volume and the background color

Developing Generalized Volume Sampling and Volume Shading for Non-Photorealistic Rendering

This paper presents a methodology for sampling and rendering 3-dimensional (3D) volume data to give it the appearance of classical ink-and-paint techniques. Although tremendous strides have been made in the realm of realistic volume rendering, research on rendering techniques for non-photorealistic (NPR) images is limited and does not yield results that provides artists the ability to create and render volumes in a classical animation style. Currently, the industry standard is to render the volume using 3D volume data and the diffuse channel, or to provide a card and play an image sequence on the card. This paper discusses a technique that allows for the non-photorealistic rendering of 3D volume data which can be used to sample and shade a variety of shapes to create a stylized render of a volume, similar to classical ink-and-paint techniques. This approach can be summarized in the following steps: (1) Scatter point data within 3D volume data based off of density values, or create a custom point cloud; (2) Ray cast from the camera to the hit position of the volume; (3) From the hit position of the ray, cast towards a direction (either towards a light for shading, or continue in the same direction for a headlamp effect); and (4) Tally and normalize the number of scattered points within a radius of the direction of said ray; then (5) Use this value to interpolate between the lit color of the volume and the background color

Developing Generalized Volume Sampling and Volume Shading for Non-Photorealistic Rendering

This paper presents a methodology for sampling and rendering 3-dimensional (3D) volume data to give it the appearance of classical ink-and-paint techniques. Although tremendous strides have been made in the realm of realistic volume rendering, research on rendering techniques for non-photorealistic (NPR) images is limited and does not yield results that provides artists the ability to create and render volumes in a classical animation style. Currently, the industry standard is to render the volume using 3D volume data and the diffuse channel, or to provide a card and play an image sequence on the card. This paper discusses a technique that allows for the non-photorealistic rendering of 3D volume data which can be used to sample and shade a variety of shapes to create a stylized render of a volume, similar to classical ink-and-paint techniques. This approach can be summarized in the following steps: (1) Scatter point data within 3D volume data based off of density values, or create a custom point cloud; (2) Ray cast from the camera to the hit position of the volume; (3) From the hit position of the ray, cast towards a direction (either towards a light for shading, or continue in the same direction for a headlamp effect); and (4) Tally and normalize the number of scattered points within a radius of the direction of said ray; then (5) Use this value to interpolate between the lit color of the volume and the background color

Hyper-Realist Rendering: A Theoretical Framework

This is the first paper in a series on hyper-realist rendering. In this paper, we introduce the concept of hyper-realist rendering and present a theoretical framework to obtain hyper-realist images. We are using the term Hyper-realism as an umbrella word that captures all types of visual artifacts that can evoke an impression of reality. The hyper-realist artifacts are visual representations that are not necessarily created by following logical and physical principles and can still be perceived as representations of reality. This idea stems from the principles of representational arts, which attain visually acceptable renderings of scenes without implementing strict physical laws of optics and materials. The objective of this work is to demonstrate that it is possible to obtain visually acceptable illusions of reality by employing such artistic approaches. With representational art methods, we can even obtain an alternate illusion of reality that looks more real even when it is not real. This paper demonstrates that it is common to create illusions of reality in visual arts with examples of paintings by representational artists. We propose an approach to obtain expressive local and global illuminations to obtain these stylistic illusions with a set of well-defined and formal methods.Comment: 20 page