VOLUME VISUALIZATION OF TEMPERATURE IN HAMILTON-HARBOR, LAKE-ONTARIO

The inner structures of lakes can be revealed using volume visualizati on algorithms since lakes are three-dimensional objects that are explo red by taking samples at various stations and at different depths. The se algorithms did not exist 20 years ago, they could only be run on su percomputers 10 years ago, on workstations 3 years ago, and now they c an be run on personal computers. Using computer graphics it is now pos sible to combine data, their three-dimensional location, and lake topo graphy to create images of water quality patterns which supersede conv entional surface, two-dimensional, graphics. Through solid modeling, t emperature data collected on 28 May 1990 and 8 August 1990 in Hamilton Harbour, Lake Ontario, are mapped into voxels and projected onto two- dimensional screens. Various three-dimensional representations of temp erature data are displayed including water masses with temperatures of less than 12 degrees C, 13 to 14 degrees C, 16 degrees C to 17 degree s C, and greater than 23 degrees C. The calculation of the 3D represen tations allows the computation of volumetric properties, e.g., masses, since each voxel has water quality values associated with it and thes e values can be summed or elaborated numerically as needs arise. For e xample the harbor has a volume of 254 x 10(6) m(3), and the water mass on 28 May 1990 at 12-13 degrees C had a complex three-dimensional sha pe with a volume of 61 x 10(6) m(3). A third benefit of visualization is that the data can be viewed interactively from different viewpoints thus increasing the interaction between scientist and the data. These methods should also be able to be used in other limnological applicat ions such as visualization of sediments, algal blooms, and other biolo gical and chemical data.