The thermal camera has revolutionized our understanding of heat transfer across many fields. In particular, it has enabled the visualization of surface temperature fields, which were previously only accessible through point sensors. However, thermograms are often difficult to interpret and can only be obtained from existing scenes. To understand them and extrapolate their insights to projects that have not yet been realized, a digital twin is required. This book examines how the finite element method facilitates the creation of idealized thermograms that both explain and extend measured situations. Finite Element Thermography addresses steady-state and transient heat transfer, starting from diffusion equations. Their discretization leads to the classical formulation of the finite element method. This book then discusses thermal radiation, with the final chapter exploring the challenges of representing results and adapting them for the calculation of derived quantities, such as the mean radiant temperature.