1. A method for identifying linear objects in an image comprising: identifying, in a processor of a computer processing device, terrain types in the image; generating, in the processor, a gradient vector image from the image, the gradient vector image identifying a gradient magnitude value and a gradient direction value for each pixel of the image; identifying, in the processor, lines in the gradient vector image using the identified terrain types in each portion of the image; determining, in the processor, whether the identified lines are perpendicular, collinear, or parallel to another line among the identified lines in the gradient vector image; eliminating, in the processor, lines among the identified lines which are determined to not be perpendicular, collinear, or parallel to another line among the identified lines in the gradient vector image; and identifying, in the processor, linear objects using the remaining identified lines which have not been eliminated.