I've been playing around with Painter X3's new Perspective Guides, which can be used to snap brush strokes to the lines of perspective. In this image, I started with a shot I took of Chicago from the top of the Hancock Center. I aligned a 3-point perspective grid to match the photo, then drew in the building shapes. The original photo is a daytime scene; I used a new color palette to change the cityscape to a nighttime scene.