A method for generating radio tomographic images is provided. A plurality of transceivers positioned around a region to be imaged is divided into a plurality of pixels. A control apparatus is configured to cause each of the plurality of transceivers in turn to send a signal to each of the other transceivers. The control apparatus is further configured to determine an attenuation in the received signals, generate weighing, derivative, and attenuation matrices from the signals, group the pixels into a plurality of provinces, select each province in turn and solve for a change in attenuation in each of the pixels while setting the pixels in other provinces to zero, aggregate solutions from each of the provinces into a rough estimate, re-solve each province using the aggregated rough estimate, aggregate the re-solved solutions from each province into a refined estimate, and generate an image from the refined estimate.