The second of two Empire Strikes Back special effects specials, this quote (Cinefex #3, page 6) on the design of the AT-AT mentions this painting:
The look of the snow walker was the result of some inspired thinking on the part of its designer, Joe Johnston. "George Lucas and Gary Kurtz knew at the outset that there was going to be a snow battle, and they knew we were going to have armored speeders. But they hadn't really decided on what kind of vehicles the Empire would have or how they were going to do it. At first they considered using existing military tanks from the Norwegian army, redressing them to make them look alien. I did a bunch of sketches using the tanks as a basis. Then I ran across a xerox that a friend of mine had. It was a promotional brochure put out by U.S. Steel in the early Sixties and contained a whole slew of full-color paintings indicating 'what still will be used for in the future.' The paintings were done by Syd Meade (sic) (Star Trek conceptual artist). Interestingly enough, one of the paintings showed a four-legged walking truck! That's here the initial walker idea came from. It was a very unique design."
Meade's (sic) rendering reflected the rich imagery of the science fiction pulps and could have easily been a surreal version of a Popular Mechanics cover. Johnston took that design and started militarizing it, giving it guns and a separate head. He also used copies of some design sketches by Ralph McQuarrie as an added influence. During the selection process, Lucas, Kurtz, McQuarrie and Johnston gathered in a room. Lucas would extract a few sketches from the batch and comment on the design features he desired. Eventually the final design of the snow walker was realized. "It was more or less up to me." said Johnston. "It amounted to a few sketches. Ralph at that time, was going to England to do some paintings and full-size sets, so he wasn't too involved in the end of the design phase. The walker you see on the screen is basically my design, with some borrowed elements from the original painting."