Thomas Hardy seems to use several methods to create the setting of both "The Darkling Thrush" and "At Castle Boterel."
In "The Darkling Thrush," imagery is used to a great extent. Words that deal with the theme are capitalized, and several of those pertain to nature. The poem centers around nature, primarily, and at the core is the thrush.
Imagery that provides a more vivid setting is found in:
I leant upon a coppice gate
When Frost was spectre-gray,
And Winter's dregs made desolate
The weakening eye of day.
The tangled bine-stems scored the sky
Like strings of broken lyres,
And all mankind that haunted nigh
Had sought their household fires.
This first stanza describes the poem's setting, and even sets the mood. The reader finds himself at a frost-covered gate, near the closing of a day in winter, and most people about have hustled home to a warm fire. This is the setting that prepares the reader for the rest of this "heart-warming" poem. (By the way, "...like strings of broken lyres" is a simile.)
In Hardy's "At Castle Boterel," the setting, as in a novel or play, is placed once again at the beginning. And imagery brings a particular place to mind:
As I drive to the junction of lane and highway,
And the drizzle bedrenches the waggonette,
I look behind at the fading byway,
And see on its slope, now glistening wet...
The reader sees the subject of the poem at a crossroads during a light drizzle. The irony of this setting is that it is presented very simply, as ordinary as any other day, it would seem.
However, as the poem commences, the speaker notes that even though life comes and goes at the crossroads where he sits, his time spent there was anything but "everyday." "Crossroads" here may indicate that he was at a figurative crossroads, where a life-altering decision would be made. The simplicity of the setting, provided with the clear and inconspicuous imagery, allows the poet to take the reader completely unaware, at the poem's conclusion—to a startling realization about the significance of his time there that day.
The setting in both starts out by using imagery to set the stage for what is to come. There is a great deal of nature imagery in "The Darkling Thrush," whereas the imagery at the onset of "The Castle Boterel" is more graphic or tangible, like a roadmap. The poems also are very different, with a completely different mood, but a similar message regarding first impressions and transition/change.