We introduce the contour spectrllm, a user interface component that improves qualitative user interaction and provides real-time exad quantification in the visualization of isoconlours. The contour spectrum is a signature consisting of a variety of scalar data and conlour attributes, computed over the range of scalar values wE!R. We explore the use of surface area, volume, and gradient integral of the contour that are shown to be univariate B-spline functions of the scalar value w for multi-dimensional unstructured triangulal' grids. These quantitative propcrties arc calculated in real-time and presented to the user as a collection of signature graphs (plots of functions of w) to assist in selecting relevant isovalues Wo for informative visualization. For timevarying data, these quantitativc properties can also be computed over time, and displaycd using a 2D interface, giving the user an overview of the time-varying function, and allowing interaction in both isovalue and timestep. The effectiveness of the current system and potential extensions are discussed.