Is there any way (perhaps within Blender or any other tool) to obtain orthographic images from a couple of photographs in perspective? That would be extremely helpful as not always you have the "luxury" of orthographic blue-prints or images. Thanks in advance for any reply.
If I understand your question correctly, you want to be able to take a perspective photo of something fairly planar with right-angle lines (shown at angles to each other in the perspective photo), and re-project the photo so that these angles are orthogonal to each other without the perspective shift?
I haven't figured out how to do it in blender yet, but Hugin (free and I believe open source panorama tool) can do it. Here's a tutorial that describes how.