I agree with these member-it is half side of a log cabin and it is just the dark fabric that makes it look 3D. Sometimes I look at quilts and feel overwhelmed and then I take a deep breath and pay attention as to how it is constructed. The picture you posted looks quite easy and "Barb in Louisiana" gave you a fantastic picture and layout of what you need.
Have fun making the 3D quilt if you choose to make that pattern.