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Aircraft display method?

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I was wondering how the real aircraft draws the information on the displays. How do they achieve the fluid and "no-jaggies" display? Is it more like a TV instead of a computer display?/Mikkel

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Hi Mikkel, Basically, in the real thing, the computers that draw the graphics do nothing else but to draw graphics. They don't really have to evaluate differential equations to determine where the airplane is going: They can just measure it ;-) I have on several occasions been in the jumpseat in a -700 version. On one of those occasions, the captain told me that the FMC is basically powered by something that roughly equates to a 386 processor :-) Funny to think about, but then again that computer does not have to drive any other stuff like graphics, sound, solve equations etc.Hope this helps,BoazEKCH

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Also, aircraft displays work completely differently to TV/Computer monitors. While a monitor/TV draws a picture line by line, aircraft monitors draw entire symbols at once. On PFD's, you'll first have the attitude deviation indicator, then the speedtape (again made up of different components), then VSI etc...This adds a lot to the smoothness. You'll also notice, on avionic photos, that sometimes not everything is visible. This is then because the shutter of the camera was too fast and not every information was available at the time of exposure.Note, you can achieve the same type of smoothness with PC's, but just not with MSFS. Check out X-Plane, which runs in OpenGL. Its smoothness is actually better than that of the real simulator!Regards,Mark

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Thanks...that's what I was looking for. So basically there are just a number of symbols waiting to be drawn in one go instead of the computer updating the whole display line by line.I don't think the processing power has much to do with the smoothnes of the display. You could hook a cray computer up to fs9 and it would still have jagged edges and choppy display. I think it's a matter of the technology behind the displays that make up for the smoothness, like mark said./Mikkel

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Mikkel-excuse me, but I take great pride at making our PMDG displays as "jaggie-free" as possible... do you still see jaggies in them? If yes, where? I'd love to fix!Cheers

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I didn't mean to give you the impression that something was wrong with the PMDG aircraft. I was just wondering how the real aircraft displays it's information.Just out of curiousity...how does your display compare with the display from RealityXP, if you have to be honest. I tried the demo located here in the avsim library and it seems very sharp and fluid. Here I'm wondering about the way/technology used to display the information.Btw...I think your displays are among the very best in the flightsim business./Mikkel

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Actually, on the 737NG, LCDs are used, which work differently from CRTs with their symbol generators. The latter 'draw' the symbols one by one on the CRT. On LCDs, the image is sent to the display as a full screen bitmap, after being compiled internally by the DU, the display unit.The image is not anti-aliased, and thus not jaggie-free!The screens are big though and high res.

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I can only comment on RealityXP's JL2 and JL4 gauges. I don't have the Meridian, which also comes with RXP gauges ...RealityXP are very proud of their filtering technology, which took them a lot of time to develop and might be even smoother (funny word ;)) than the PMDG displays. The big difference, in my opinion, is that PMDG has a lot more to offer on the "content" side - they created a realistic airliner cockpit instead of some generic displays. I'd also rate the readability of PMDG's display units higher.Just my 2c (EUR),VOlker :]

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Ian, that's a CRT you're displaying here. The CRT uses line drawing and raster filling. That's why the drawn lines are jaggie free, because they're drawn, while the blue and brown filled areas are filled using raster filling, which is the same pattern filling used as the build-up of a TV screen.LCDs have a fixed native resolution, just like a TFT monitor. But, no anti-aliasing is used on them (they're high res anyway, jaggies are not noticable and the lack of anti-aliasing gives a sharper image).

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Hi, bumping in:If that's a real 747-400 EADI, then it can not be CRT, because the 747-400s uses LCDs on the cockpit (like all modern aircraft). CRTs are used on 767/757 and contemporary aircraft.Just my 2 cents,Joselito

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>Man, I really tought the 747-400 had the same DU's as 777.>>Thanks,>>JoselitoWell, I wasn't all that wrong after all...hehehe.I still tought I had seen LCDs on 747-400, then I went to Boeing website and quoted from there:"At the end of 2002, these CRTs will be replaced with new Liquid Crystal Displays (LCDs) on all new 747-400s. These LCDs provide higher reliability and more capability for new functions to be incorporated in the future."http://www.boeing.com/commercial/747family/back/back5.htmlRegards,Joselito

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"Ian, that's a CRT you're displaying here."Ooops... my mistake, Iz... I thought the question was referring to aircraft glass cockpit displays in general (which are, relatively, jaggie-free, compared to desktop sims)."while the blue and brown filled areas are filled using raster filling"Mmmmm, my favourite.... raster filling..... Sounds yummy :-)Cheers.Ian.P.S. So the Wx Radar and Terrain is also now non-raster on the new LCD displays?

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Well, it looks about the same, except that on an LCD, every pixel is given a colour, and you can't really speak of filling an area, whereas on a CRT, the photon-cannon actually fills the area.

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