Ion Canon Control Room Miniature Set.

Shown in Empire of Dreams Documentary

Comparison to McQuarrie Concept Art.
Does the Model Still exist?
I suppose this is really an early dropped idea but I am more curious about the model than the planned scene that was probably scrapped due to not being convincing enough.
Some more info on general Veers Death from star wars affectionado blog spot.
http://starwarsaficionado.blogspot.co.uk/2011/09/aficionado-exclusive-first-look.html
"Actor Julian Glover, who played Veers, told me that he never filmed a death scene for the character, so this live action sequence showing his demise, which is in the novelization, is something that I think was completed in insert photography at some point later in the filming, and presumably not with Glover (either at ILM or ELSTREE) with stand-ins and stuntmen for the final live-action insert, especially as we don’t see Glover’s face in the sequence: there’s no way a film director would have an actor film in front of such a large pyrotechnic, for both safety and insurance reasons…"
What is factual about this is that the actor who played general veers was not the actor in the scenes for his death. So far as pyrotechnics are concerned and exposing actors to them.... Nope if it's done safely there are literally little problems in exposing actors being present near pyrotechnics as long as safe distances are observed.
There is also the Red stripe on the AT-AT drivers Helmets so it is perhaps obvious to tell which shots were later pick up shots with a wardrobe malfunction and not the original actors. Filmed at a different time because they wanted to alter or add an idea or a few ideas.

So this points to general veers death being an insert done in Elstree as the cockpit set was no doubt there possibly after principle photography ended or atleast after Julian Glover had finished his scenes... But there is more to explore about this sequence at the end.

is that smoke billowing from the Hanger Entrance?
They then re-used this background plate to show the shield generator explosion!!! oh dear what a muddle this film is in.

So can it be inferred that the troops running back to echo base were nothing to do with the shield generator explosion at all?
And the shield generator suddenly appearing in a background that we saw only a few seconds earlier is more or less a bodge job because the sequence was originally intended to have general veers die and they needed to fill the extra seconds with something that they had to cook up at the last minute?
The sound mix is also extremely telling of it not being right in terms of the sound effects for the actual explosion and it's placement in the timeline. It was definitely not remixed to suit a changed scene order.
I have not read the novel of the Empire Strikes Back but to have a guess I imagined "Hobbie" flying through the explosion of the shield generator coming through the flames and using it as a cloak so as not to be seen until he was right upon general veers AT-AT?
But that is of course unless the intention was changed to the Snow speeder that gets destroyed by the AT-AT and crashes on the action plate pictured was an altered version of the suicide run?
So at some point a decision was made to include general Veers death and then a decision to alter it to something else for which they had neither the time or money to complete it properly.
EDIT:
I don't think that is smoke coming from the Hanger or that is the Hanger anymore although it would have been nice to see the troops make it back somewhat safe. So they don't appear to be running anywhere specific just away.
The actual explosion of the Shield generator is not mentioned in the script in terms of it having a scene number or having a description of being seen from the AT-AT cockpit.
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I have been looking in to the music that was meant to introduce the AT-AT's some more and what I can tell you is that there are 2 shots of when Luke is trying to escape from his Snow Speeder before it get's crushed by a big AT-AT foot.
The 2 shots (or atleast 2) that feature the AT-AT foot stomping down and other shot of the Legs with background plate were the original introduction to the AT-AT's that were meant to have the piano riff that came before the soldier looks out of his binoculars.
So in this case I will take off my hat and call it clever editing on this part but it is a very clear reason of why the music was removed also and it also calls in to question Luke trying to escape from his Crashed Snow Speeder is clearly another unfinished sequence, and it got chopped in half and spread due to a missing shot where Luke was meant to see the underbelly of the Walker tower over him. But as far as the script is concerned here this shot was actually a pretty unreasonable shot to achieve for the ILM crew in terms of achieving that shot which would have been all sorts of difficult and I put that down to a hurdle that could not be overcome by technical limitations and inconsiderate script. There is also alternative storyboards for this sequence and this does explain why the AT-AT does not fire it's weapons as the shots were intended for the introduction before the battle had begun.
The internal cockpit shot of the AT-AT approaching before Luke opens the Hatch could also probably not be completed due to not being able to match the snow on the window from the live action in Norway another difficult demand from script to screen.
So In terms of answering The North Ridge music I think I have a pretty full answer here now but because it is intrinsically linked with Luke escaping from his crashed Snow Speeder it is yet another mystery that is raised by solving another.
It explains why the AT-AT never feels like it gets any closer because the shots were never meant for this part of the film where Luke tries to escape the crash.
EDIT:
No No No, I made a mistake here the shots were not moved.. Urrgh this is really tricky to work stuff out so apologies.
The introduction to the AT-AT simply had a shot of a foot very similar to the one we see while Luke is trying to escape is crashed Snow Speeder but it also lifts out of frame that goes with the Piano riff... The Shots of the feet when Luke has crashed were additions not mentioned in the script so my Bad but I will leave my mistake on this visible because I really don't want to appear like I am being big headed or anything like that. I just seriously want to work out the processes and changes that were made either for better or for worse and try to understand it better.