An apparatus and method for mapping film thickness of one or more textured polycrystalline thin films. Multiple sample films of known thickness are provided. Each sample film is irradiated by x-ray at a measurement point to generate a diffraction image that captures a plurality of diffraction arcs. Texture information (i.e., pole densities) of the sample film, is calculated based on incomplete pole figures collected on the diffraction image and used to correct the x-ray diffraction intensities from such sample. The corrected diffraction intensities are integrated for each sample film, and then used for constructing a calibration curve that correlates diffraction intensities with respective known film thickness of the sample films. The film thickness of a textured polycrystalline thin film of unknown thickness can therefore be mapped on such calibration curve, using a corrected and integrated diffraction intensity obtained for such thin film of unknown thickness.