Treemaps use automatically generated sizes that cannot be resized by using the Marks card. A treemap is a type of visualization that shows hierarchical data as a set of nested rectangles. Each rectangle represents a dimension member and its size is proportional to a measure value. Tableau automatically calculates the size of each rectangle based on an optimal aspect ratio for readability and comparison. You cannot manually adjust the size of each rectangle by using the Marks card or any other option in Tableau10 The other chart types do not use automatically generated sizes that cannot be resized by using the Marks card. Pie charts use angles to show proportions of a whole, not sizes. Histograms use bins and frequencies to show distributions of a measure, not sizes. Area charts use filled areas to show trends over time or categories, not sizes. You can adjust the size of these chart types by using the Marks card or other options in Tableau