Abstract: A method, system, and computer-readable storage medium are disclosed for distortion-based mask generation. A respective distortion metric may be determined at each location of a plurality of locations in a two-dimensional representation of a three-dimensional object. The two-dimensional representation may be based on a view of the three-dimensional object. Each respective distortion metric may indicate a degree of distortion in a mapping between the respective location in the two-dimensional representation and a corresponding location in a surface texture of the three-dimensional object. The visual representation of the respective distortion metric at one or more of the plurality of locations may be displayed.

Abstract: Methods and apparatus for providing a local coordinate frame are described. A user may place the tips of all five digits on a multitouch user interface with a natural gesture to provide five touch points. A local coordinate frame may be constructed from the touch points. A local coordinate frame may be computed relative to the entire hand and/or relative to each individual digit. The technique may be agnostic in regard to the orientation of the device and to which hand is used. The user may move or rotate their hand, and the local coordinate frame is adjusted to the new positioning relative to the device. The technique may also infer a relative position of the palm from the digit input points, allowing the display of user interface elements where the elements are visible rather than occluded by the hand.

Abstract: A method, system, and computer-readable storage medium are disclosed for simulation of an erodible tip. A brush tool representing an erodible media is modeled as a height map. Information is collected about a user manipulation of a stylus representing a stroke made on a virtual canvas with the brush tool. A mark to be made on the virtual canvas is determined dependent on the brush tool model and the collected information. The determined mark is rendered. A change in the height map of the brush tool due to the stroke is determined dependent on the brush tool model and the collected information. One or more subsequent marks are rendered in response to manipulation of the brush tool dependent on the determined change in the height map.

Abstract: Systems, methods, and apparatus for simulating natural media painting in a digital painting application (or painting simulation module) using a two-layer model of a virtual paint brush may more accurately simulate real world painting techniques than conventional painting simulations. A two-layer brush model may include a reservoir buffer and a pickup buffer to separately represent the paint stored in the belly of a paint brush tip and paint that has been picked up on the surface of the brush tip during a brush stoke, respectively. The two-layer brush model may also include methods that automatically control how virtual paint moves between these layers and a digital canvas. In simulations that employ this two-layer brush model, virtual paint may be deposited on the digital canvas directly from both of the buffers. The amount of paint deposited from each buffer (and/or the ratio of the amounts) may be configurable by a user.

Abstract: Techniques for improving the performance of vector-based, fluid motion simulation techniques in procedural painting algorithms. The techniques may be implemented in procedural painting algorithms that employ a vector-based, fluid motion simulation technique to help achieve dynamic and serendipitous behaviors of watercolor painting at good interactive rates even on relatively low-powered devices. The techniques may include resampling the vertices of pigment polygons after growth at least at some iterations of the algorithm to provide smoother, more uniform growth; rasterizing dried pigment polygons into a texture so that the dried polygons are not rendered at each iteration of the algorithm; and rendering only a subset of live pigment polygons at each iteration of the algorithm. Polygons used by the techniques may be separated into static water polygons and dynamic pigment polygons.

Abstract: Methods and apparatus for providing a local coordinate frame are described. A user may place the tips of all five digits on a multitouch user interface with a natural gesture to provide five touch points. A local coordinate frame may be constructed from the touch points. A local coordinate frame may be computed relative to the entire hand and/or relative to each individual digit. The technique may be agnostic in regard to the orientation of the device and to which hand is used. The user may move or rotate their hand, and the local coordinate frame is adjusted to the new positioning relative to the device. The technique may also infer a relative position of the palm from the digit input points, allowing the display of user interface elements where the elements are visible rather than occluded by the hand.

Abstract: Techniques for improving the performance of vector-based, fluid motion simulation techniques. The techniques may be implemented in procedural painting algorithms that employ a vector-based, fluid motion simulation technique to help achieve dynamic, serendipitous behaviors of painting at good interactive rates even on relatively low-powered devices. Instead of employing polygons in a procedural painting algorithm that are combinations of pigment and water, a technique may be employed in which the polygons are separated into pigment polygons and water polygons. The water polygons are not rendered; only the pigment polygons are rendered. To improve the performance of the wetness determination at vertices of the pigment polygons, a technique may be used that first rasterizes all of the water polygons into a buffer, which may be referred to as a wetness layer or wetmap; the wetness at a vertex is then determined by sampling this buffer or layer at the vertex's position.

Abstract: Methods and apparatus for providing a local coordinate frame user interface. A local coordinate frame user interface is described that may be used in conjunction with other tools provided by an application such as a graphical input and editing application. A user may draw or modify graphical objects using strokes applied with a brush or other tool, or perform other input and editing operations of the application, with one hand. While performing these various operations with one hand, the user may invoke and manipulate the local coordinate frame user interface with the other hand. Using this combined graphical input and editing method, a user may quickly adjust various attributes of selected tools and/or drawn objects, switch drawing tools or modes, and perform various other adjustments and actions via the local coordinate frame user interface with one hand while performing other actions with the other hand.

Abstract: A method, system, and computer-readable storage medium for simulating bristle brush behavior in an image editing application may use stiffness-height parameterization to determine the height of a brush tool above a canvas during a brush stroke. The determination may be dependent on the pressure applied during the stroke (e.g., using a stylus on a pressure-sensitive tablet), and on the stiffness of the brush bristles. The system may select a standard-stiffness or high-stiffness mapping between stylus pressure values and brush height values dependent whether the bristle stiffness value is above or below a pre-determined threshold. The standard-stiffness mapping may apply a linear function to pressure values to determine height values. Using the high-stiffness mapping, the effect of increased pressure on corresponding brush height values may be reduced as bristle stiffness is increased.

Abstract: Systems, methods, and apparatus for simulating natural media painting in a digital painting application (or painting simulation module) may provide user interface elements and methods that allow a user to load a brush with non-uniform paint colors by directly sampling the digital canvas. For example, a user may hover the brush over an area on the canvas having a non-uniform color distribution, and the application (or module) may sample the colors of the pixels under the brush, and load the brush with a collection of paint values reflecting the non-uniform distribution of colors in the sample. The application may support two non-uniform paint loading modes, e.g., one that fills the brush with a distribution of paint matching a single sample, and one that fills the brush with paint continuously as it is swept over the canvas. Non-uniform paint loading may be applied to stamp-based brush models and/or bristle brush models.

Abstract: Methods and apparatus for diffuse indirect illumination computation using progressive interleaved irradiance sampling. Embodiments may implement a method that amortizes the cost of computing the irradiance integral for diffuse indirect illumination both temporally and spatially in screen space. For each pixel, only one secondary ray is fired. By carefully arranging different secondary ray directions for different pixels according to a sampling sequence, embodiments may filter the noisy estimate so that each pixel receives a relatively uniform coverage of the integrated hemisphere. Some embodiments may use a bilateral filter so that the geometric discontinuities are respected. The sequence may continue to a higher-level of stratification in each frame. This ensures that the rendering is converging to a noise-free result.

Abstract: A method, system, and computer-readable storage medium are disclosed for distortion-based mask generation. A respective distortion metric may be determined at each location of a plurality of locations in a two-dimensional representation of a three-dimensional object. The two-dimensional representation may be based on a view of the three-dimensional object. Each respective distortion metric may indicate a degree of distortion in a mapping between the respective location in the two-dimensional representation and a corresponding location in a surface texture of the three-dimensional object. The visual representation of the respective distortion metric at one or more of the plurality of locations may be displayed.

Abstract: Systems and methods for simulating liquid-on-lens effects may provide an interface through which users can add and/or manipulate fluids on a virtual camera lens. A physically based fluid simulation may simulate the behavior of the fluid as it is deposited on and/or manipulated on the virtual lens, and determine the distribution of the fluid across the lens. A ray tracing technique may be employed to determine how light is refracted through the virtual lens and the fluid, and to render a distorted output image as seen through the lens and the fluid. As the fluid is manipulated, corresponding changes in the image may be displayed in real time. The input image may be an existing single image or a direct camera feed (e.g., of a tablet type device). The user may select a fluid type and/or various fluid properties for the image editing operation.

Abstract: Systems, methods, and apparatus for simulating natural media painting in a digital painting application (or painting simulation module) using a two-layer model of a virtual paint brush may more accurately simulate real world painting techniques than conventional painting simulations. A two-layer brush model may include a reservoir buffer and a pickup buffer to separately represent the paint stored in the belly of a paint brush tip and paint that has been picked up on the surface of the brush tip during a brush stoke, respectively. The two-layer brush model may also include methods that automatically control how virtual paint moves between these layers and a digital canvas. In simulations that employ this two-layer brush model, virtual paint may be deposited on the digital canvas directly from both of the buffers. The amount of paint deposited from each buffer (and/or the ratio of the amounts) may be configurable by a user.

Abstract: Systems, methods, and apparatus for simulating natural media painting in a digital painting application (or painting simulation module) may more accurately simulate real world painting techniques than conventional painting simulation applications. The digital painting application (or simulation module) may provide a small set of physically meaningful parameters (e.g., canvas wetness, drying rate, and pickup mix ratio). By setting the values of these parameters (or overriding default values for a selected paint type), the user may better control the appearance of brush strokes made by a virtual paint brush on a digital canvas. For example, the length of a brush stroke, the amount of streaking caused by paint picked up during the brush stroke, and/or the mix of paint deposited from a pickup buffer and a reservoir buffer of a brush model may be affected by changing the values of these parameters, thus allowing users to create different realistic painting effects.

Abstract: Systems and methods for performing brush behavior simulation in an image editing application may facilitate realistic paint simulation by the addition of a fill channel to a color space representation that includes a set of color channels and an alpha channel representing opacity of the paint. The fill channel value for each pixel of a brush model or canvas may represent the amount of paint stored at the pixel. The system may include logic to support paint compositing, mixing, and depletion operations that calculate a consequent color of a destination pixel resulting from the operations dependent on the fill channel values for the source and/or destination pixels. The resulting color channel, opacity channel, and fill channel values may be converted to a color space that does not include a fill channel or opacity channel for display. A source pixel may be a pixel of an atomic element of a texture.

Abstract: Methods, apparatus, and computer-readable storage media for fast adaptive edge-aware matting in which a matting technique adaptively feathers selections, provides smooth color correspondence matting, and performs well in textured regions. The matting technique may require fewer strokes and less parameter tuning than conventional matting techniques. The matting technique may have two components implemented in a matting pipeline. A color similarity component implements a color similarity constraint technique based on a radial basis function (RBF) technique to generate a color-constrained mask, and a locality constraint component implements a locality constraint technique based on a fast flood fill technique to generate a locality-constrained mask. The final mask (or matte) output may be an element multiply of the masks generated by the two components.

Abstract: Method and apparatus that employs one or more perceptual metrics in determining a priori a number of samples to take at each location during irradiance computation. A number of hemisphere samples to be taken at each location in a scene may be calculated according to one or more perceptual metrics corresponding to the location. Perceptual metrics that may be used may include one or more of, but are not limited to: the overall direct lighting at the location; the diffuse texture of the surface at or around the location; and the color at the location. An irradiance value for each location may be calculated according to the number of samples calculated for the location. This perceptual metrics technique for determining a priori the number of samples needed is orthogonal to conventional adaptive sampling techniques, and can be adapted for use in other irradiance computation techniques.

Abstract: Methods and apparatus for providing a local coordinate frame user interface for multitouch-enabled devices. A user interface may be provided on multitouch display devices, displayed according to a local coordinate frame constructed around the human hand. A user may place the tips of all five digits on a multitouch user interface with a natural gesture to provide five input points; the method detects which input points correspond to which digits, and constructs a local coordinate frame for the hand based on the input points. User interface elements (e.g., controls) may then be assigned to each digit and displayed on the multitouch display. The user may then selectively manipulate one or more of the displayed controls as desired via one or more gestures associated with the particular control.

Abstract: A method and apparatus for computing direct lighting in a scene is described. For a sparse set of points in the scene, occlusion information for the points and each of one or more light sources may be computed and stored. For all other surface points in the scene, nearby sample points are examined to determine if their occlusion information agrees. For any light source for which nearby sample points do not agree, lighting computation may be performed, e.g. by the casting of shadow rays. Such areas comprise regions in penumbra or shadow boundaries. For all other regions, it is assumed that they are fully lit or fully occluded, and thus the casting of shadow rays can be avoided.