We will use a recent research project to illustrate the research and development process for a practical application. The goal of the project is to accurately measure an infant’s length using an image taken from a regular cellphone camera. We first describe the background and motivation of the project, and the logical thinking in leading to a preliminary solution. We then discuss the problems we encountered in applying the solution to field trials, and the further effort in resolving the problems in order to achieve a practical solution. Finally, we summarize the lessons learned from this research project.