This paper outlines a technical approach to generate homogeneous warm scene binary mask: SHOWmask using microwave radiometer observations. The objective is to identify homogeneous desert scenes as targets in radiometric intercalibration of multi source multi-sensor systems. In the current paper a method is developed to generate mask on continental Australia using 10 GHz and 18 GHz Vertical and Horizontal polarized radiance observation from Global Precipitation Monitoring Mission Core observatory Microwave Imager (GMI) data. Major factors considered are diurnal variation, spatial homogeneity and surface emissivity. Major advantage of this tool is its minimal, almost negligible, dependence on any external ancillary modeled or observed data.