1. A method of determining the location of a wireless measurement device, comprising: developing a computer-based map of locations in which the wireless device will be used; sparsely populating the map with low-density nodes each of which is associated with a respective location on the map; training the locations by measuring signal properties received at calibration nodes associated with each of the low-density nodes; generating signal strength distributions for each of the calibration nodes based upon the received signal properties; populating the map with high-density nodes that are interspersed among the low-density nodes; generating a transition probability for each pair of high-density nodes based upon path constraints between the nodes; generating observation probabilities for each of the low-density location nodes; processing the signal strength distributions, transition probabilities, and observation probabilities to generate a probability value for each high-density node; and interpolating the probability that the wireless device is at one or near one of the high-density nodes based upon the probability values of the low-density nodes.