A device may include a first set of electrodes; a second set of electrodes transversely oriented from the first set of electrodes; and a processor and memory, where the memory has programmed instructions to cause the processor, when executed to: activate a first portion of electrodes in the first set, measure a first resulting capacitance from activating the first portion of electrodes with at least some electrodes of the second set, activate a second portion of electrodes in the second set, and measure a second resulting capacitance from activating the second portion of electrodes with at least some electrodes of the first set.