She drew a row of trees receding into the distance to demonstrate the laws of perspective.

她画了一排由近而远高度递减的树以演示透视图的规律。

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For instance, the kiosk explains that Rothermel's deliberate perspective puts the viewer 125 yards from the copse of trees just below Cemetery Ridge in an area of the battle line known as "the Angle, " a jog in the stone wall defended by the Philadelphia Brigade.

WSJ: Capturing Gettysburg | Objects of Valor | State Museum of Pennsylvania | By Mark Yost

You're just so close to it and you sometimes lose perspective, you can't see the forest for the trees, that sort of thing.

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