Abstract: The present invention enables the measurement and determination of a quantity over a selected spatial region by providing a device that incorporates a sensor for the measurement of the quantity and a spatial subsystem for determining the spatial information comprising a spatial position and/or orientation of the device when the measurement is made. A processing module integrated with the device operates on a dataset of multiple measurements correlated with spatial information and provides a determination of the quantity over the selected spatial range, either directly based on the measured data point and the spatial information or via a sensor fusion algorithm such as an interpolation algorithm. The results may be displayed on the device, for example, on a graphical display, or may be transmitted to a remote processor for subsequent processing and/or display.