  We recast the Howie-Whelan equations for generating simulated transmission
electron microscope (TEM) images, replacing the dependence on local atomic
displacements with atomic positions only. This allows very rapid computation of
simulated TEM images for arbitrarily complex atomistic configurations of
lattice defects and dislocations in the dynamical two beam approximation. Large
scale massively-overlapping cascade simulations performed with molecular
dynamics, are used to generate representative high-dose nanoscale irradiation
damage in tungsten at room temperature, and we compare the simulated TEM images
to experimental TEM images with similar irradiation and imaging conditions. The
simulated TEM shows 'white-dot' damage in weak-beam dark-field imaging
conditions, in line with our experimental observations and as expected from
previous studies, and in bright-field conditions a dislocation network is
observed. In this work we can also compare the images to the nanoscale lattice
defects in the original atomic structures, and find that at high dose the white
spots are not only created by small dislocation loops, but rather arise from
nanoscale fluctuations in strains around curved sections of dislocation lines.
