A method for determining the area of an analysis chamber covered by a biologic fluid sample quiescently residing within the chamber is provided. The chamber has a first panel with an interior surface, and a second panel with an interior surface, both of which panels are transparent. The method includes the steps of: a) illuminating the sample residing within the analysis chamber at one or more wavelengths operable to highlight interfaces between the sample and air, and to highlight a constituent within the sample; b) imaging the sample along the one or more wavelengths, and producing image signals representative of the interaction of the one or more wavelengths with the sample; c) determining a location of at least one interface between the sample and air, using the image signals; d) determining a location of one or more constituents within the sample relative to the at least one sample-air interface using the image signals; and e) determining an area of the chamber containing the sample, using the location of the one or more constituents and the at least one sample-air interface.