Image-Space Collage and Packing with Differential Rendering

1Shenzhen University, 2Tel-Aviv University
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Visualization created by our shape collage technique, from left to right: (top) square map, circular packing diagram, text themeriver, (bottom) word cloud, pie chart, and bubble barcharts.

Abstract

Collage techniques are commonly used in visualization to organize a collection of geometric shapes, facilitating the representation of visual features holistically, as seen in word clouds or circular packing diagrams. Typically, packing methods rely on object-space optimization techniques, which often necessitate customizing the optimization process to suit the complexity of geometric primitives and the specific application requirements. In this paper, we introduce a versatile image-space collage technique designed to pack geometric elements into a given shape. Leveraging a differential renderer and image-space losses, our optimization process is highly efficient and can easily accommodate various loss functions. We demonstrate the diverse visual expressiveness of our approach across various visualization applications. The evaluation confirmed the benefits of our method in terms of both visual quality and time performance.

Animation of the collage process

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How Does it Work

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Image-space Collage Framework: taking the initialized vector primitives as input, image-space losses are calculated between the rasterized image and the target image. These losses are used to update the parameters in the geometric transformation, which in turn updates the vector primitives.

Results

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Illustrative Visualization: by placing attracting points in different locations, visual effects that simulate the force of attraction can be achieved..
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Packing diagrams of words and shapes generated by our technique: (a-c) word clouds, (d-f) regular shapes, (g-k) irregular icons.

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