There are many ways to visualise a space or external facade. One of the techniques we use to explore textures and materials is a 'flat' photoshop image with ghosted white lines. These images are usually extracted from 3d views. However, to translate a vision or a colour palette it is often better to show less. As Mies van der Rohe said, 'less is more'.
Sometimes shadow is not needed as in fig.1. Although slight changes intone help give a sense of perspective. Colours and textures added with a few 'props' tell a simple story that anyone can understand.
Composition and proportion are other key components of creating beautiful and well balanced buildings. It is usually the buildings that haven't dealt with these two things that stand out the most and are jarring to the eye. Careful consideration of window placement and scale can transform the simplest of elevations into elegant forms along a street.
Shadows were needed in Fig.3 to show the multilayered facade. The freestanding walkways needed to come out of the page and show the staggered nature of this particular project.