Time inheritance scene graph for representation of media content
First Claim
1. A method of specifying a choreographed media production as a graph of nodes and acyclic directed paths defining related sets of forward and reverse traversals comprising the steps of:
- (b) adding to the graph a leaf node with a data-generation function that generates in a reverse traversal data related to the choreographed media production based on a temporal context;
(c) adding to the graph an intermediate node with a temporal transform that takes a temporal context as an input and derives a new temporal context as the output, during a forward traversal, and then restores the forward traversal'"'"'s input temporal context during the corresponding reverse traversal; and
(d) connecting the intermediate node into the graph with a directed path that defines both a forward traversal that carries a temporal context from the root node through the intermediate node to the leaf node and a symmetric reverse traversal that begins when the forward traversal is completed and ends at the root node;
wherein the root node defines both a spatial context and temporal context, the intermediate node includes the ability to apply a spatial transform during forward traversal and reverse this spatial transform during reverse traversal, and the leaf node bases its data-generation function on both the spatial context and temporal context.
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Abstract
A technique for representing a visual scene as a directed acyclic graph of data and operators that generates a sequence of image frames over specified time intervals. The graph specifies temporal and spatial values for associated visual elements of the scene. Time is modeled in the inheritance properties explicitly defined within the scene graph hierarchy, by assigning temporal attributes to each media element. Branch nodes of the graph specify transforms for the temporal and spatial coordinate systems. To evaluate the appearance or behavior of the scene and in particular the global time values of particular elements at a given time instant, the graph is traversed in a direction from a root node down toward the leaf nodes, thereby causing temporal transformations specified along the branches of the graph to modify time parameters of the scene data at the nodes. Child nodes are preferably evaluated after being transformed, to determine the extent to which they contribute the data to the final scene. Temporal transformations may include translation operations that offset temporal event times; scaling operations that change the rate at which time passes; or clipping operations, that restrict the range of time parameters to exclude the evaluation of parts of the graph.
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Citations
19 Claims
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1. A method of specifying a choreographed media production as a graph of nodes and acyclic directed paths defining related sets of forward and reverse traversals comprising the steps of:
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(b) adding to the graph a leaf node with a data-generation function that generates in a reverse traversal data related to the choreographed media production based on a temporal context;
(c) adding to the graph an intermediate node with a temporal transform that takes a temporal context as an input and derives a new temporal context as the output, during a forward traversal, and then restores the forward traversal'"'"'s input temporal context during the corresponding reverse traversal; and
(d) connecting the intermediate node into the graph with a directed path that defines both a forward traversal that carries a temporal context from the root node through the intermediate node to the leaf node and a symmetric reverse traversal that begins when the forward traversal is completed and ends at the root node;
wherein the root node defines both a spatial context and temporal context, the intermediate node includes the ability to apply a spatial transform during forward traversal and reverse this spatial transform during reverse traversal, and the leaf node bases its data-generation function on both the spatial context and temporal context. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification