1. A method of producing a visual text summarization, the method comprising the steps of: extracting a plurality of topics from a collection of text documents, wherein each of the topics comprises a plurality of topic keywords; determining an importance ranking for each of the topics; determining an importance ranking for each of the topic keywords of a topic; displaying a graph having a plurality of stacked layers representing a group of topics selected from the plurality of topics based on the importance ranking of the topics; grouping a subset of text documents included in a topic, wherein the grouping is based on a grouping constraint; selecting a subset of topic keywords included in the topic, wherein the subset of topic keywords summarize a content of the subset of text documents, wherein the at least one keyword cloud displayed within each layer of the graph is the subset of topic keywords that summarize the content of the subset of text document grouped based on the grouping constraint; and displaying at least one keyword cloud within each layer of the graph, wherein the at least one keyword cloud is a group of topic keywords selected from the extracted topic keywords based on the importance ranking of the extracted topic keywords; wherein at least one of the steps is carried out using a computer device.
1. A method of producing a visual text summarization, the method comprising the steps of: extracting a plurality of topics from a collection of text documents, wherein each of the topics comprises a plurality of topic keywords; determining an importance ranking for each of the topics; determining an importance ranking for each of the topic keywords of a topic; displaying a graph having a plurality of stacked layers representing a group of topics selected from the plurality of topics based on the importance ranking of the topics; grouping a subset of text documents included in a topic, wherein the grouping is based on a grouping constraint; selecting a subset of topic keywords included in the topic, wherein the subset of topic keywords summarize a content of the subset of text documents, wherein the at least one keyword cloud displayed within each layer of the graph is the subset of topic keywords that summarize the content of the subset of text document grouped based on the grouping constraint; and displaying at least one keyword cloud within each layer of the graph, wherein the at least one keyword cloud is a group of topic keywords selected from the extracted topic keywords based on the importance ranking of the extracted topic keywords; wherein at least one of the steps is carried out using a computer device. 12. The method of claim 1 , further comprising a step of coloring the layers in the graph, wherein layers representing semantically similar topics use a same color with different hues.