The disclosed device generates a plurality of pixel data in an XY coordinate system. The pixel data includes first pixel data generated on a first sweep line, according to a distance from a transmitting source, based on an echo of a detection signal from the source toward a first direction, and second pixel data generated on a second sweep line, according to a distance from the source, based on an echo of a detection signal from the source toward a second direction different from the first direction. The device includes a module for converting the first and second pixel data into data in the XY coordinate system, a module for generating pixel data of an interpolation target pixel located between a first pixel as an observing pixel on an interpolation axis parallel to X-axis or Y-axis and a second pixel as a corresponding pixel on the same interpolation axis, based on the pixel data on the first and second sweep lines.