1. A method in a computer system for generating pedestrian heat scores, the method comprising: receiving, by one or more processors, a pedestrian dataset that indicates position fixes for a plurality of portable devices, wherein each portable device corresponds to a respective pedestrian, including: receiving, for a first subset of the plurality of portable devices, position tracks each made up of successive position fixes from a same portable device, and receiving, for a second subset of the plurality of portable devices, single position fixes; receiving, by the one or more processors, a selection of a geographic area that contains a subset of the plurality of geographic units; generating, by the one or more processors, raw heat scores for a plurality of geographic units of equal size based on the pedestrian dataset, each raw heat score being indicative of a number of portable devices passing through a corresponding geographic unit, wherein for a target geographic unit included in the subset of the plurality of geographic units, generating the raw heat score includes: multiplying a number of position tracks passing through the target geographic unit by a first weight to generate a first product, multiplying a number of single location fixes in the target geographic unit by a second weight to generate a second product, and generating the raw heat score using the first product and the second product; generating, by the one or more processors, normalized heat scores for the subset of the plurality of geographic units based on at least some of the generated raw heat scores, to provide indications of relative intensity of pedestrian traffic at the corresponding geographic units, for use by a software application.