Stubborn compass tape in a hud

[Varmint007 2]

>Jon,>>It is simple math, and you have reified one scale is all. See>you are thinking the arc length is from the CG of the>aircraft. What you forget is the real center is the gyro. So>the arc length the distance measures is really from the center>of the gyro in any case. It is measuring degrees of>rotation.>>Imagine that I surround your aircraft with a large transparent>ball, and mark off your degrees of "sky" for you. That would>unwrap to one size of bmp.>>Now imagine I double, or half the size of the ball. The bmp>would double, or half, but the angle measured is the same.>>Same principle. The distance between the lines on each of>those balls is going to be very different, but measure the>same arc.>>So, why use twice the size ball, when you get the same effect.> In other works, there would be no apparent difference to you>in the cockpit.>>PatrickPatrick, It's possible we're talking about two different things here, and if so, I apologize for the confusion, but it sure sounds like you're saying the distance between the lines in a HUD pitch ladder can be arbitrary. If so, I continue to disagree:) If we're both talking about arcs, and we're both talking about pitch lines in a HUD, then there can only be one correct scale (pixels between lines) for a given resolution and FOV. While FS will properly scale the element for resolution, it won't hold up if the FOV changes.As far as the reference position (CG, or gyro), it's really neither here nor there, since the reference for a HUD is always the longitudinal axis, waterline, boresight, or whatever term happens to suit your particular branch of aviation. Again, this is why I think I may have missed something, since surely you'd have to agree with that:)--Jon

[Varmint007 2]

There's nothing to flame, I think we're just either not communicating our concepts correctly, or not paying attention. I'll be happy to digress if I've misinterpreted anything. But I have been doing HUDs for a long time, and I think I may have helped you with your Hornet HUD way back there somewhere.The problem you describe of achieving crispness while maintaining detail can be solved partially by using custom fonts. For example you can design a font in which a single character represents any level of detail .The picture illustrates what I mean. Note the curved pitch lines and particularly the circular, 10 degree AIM-120 visual envelope which has dashed lines. That circle and the pitch lines are each single characters in a custom font. They not only render faster than large bitmaps, they can be adjusted for hue, brightness, or anything else you can do with a vector - on the fly.The fonts can also be forced to anti-alias only above some specified fontsize (i.e. you can eliminate anti-aliasing which contributes to those nasty back artifacts you were talking about).I also hope FSX provides better facilities for HUD, particularly transparency of vectors over the rendering port.--Jonhttp://forums.avsim.net/user_files/153002.jpg

[Guest jprintz]

That's a nice looking HUD John! Yes, I've seen it before. ;-) We did have a long discussion about velocity vectors probably a year ago or something, when I was having headaches experimenting with all different kinds of variables for vector displacement (velocity world, velocity body, AoA, Beta, etc....) I think you advocated the alpha and beta method (????), but, to be honest, I found the velocity world and velocity body variables much more suitable for a true velocity vector.About the vector vs. bitmap thing, it doesn't really have to be a "vs." thing, IMO. You've communicated the advantages of vectors quite well, I for one certainly agree with them(!), and I think only a fool would argue those points. Your HUD definitely has a nice crisp look to it. On the other hand... if I were going to be completely honest (and this is in no way meant as a slam against you), I would say that it also demonstrates my previous point, in that it suffers from the very thing I mentioned earlier about authenticity - while in your pic all the elements are there, and they all look good and I'm sure function properly on their own, something about the "whole" of it just really doesn't seem to match the look and feel of the real Hornet's HUD. (See attached pic... not the best one, but still....) The scale or spacing or relation between the elements has just not been duplicated. And I don't see my comment as a slam against you because... that would be EXTREMELY difficult to do with vectors!!! That is my point. I'm sorry for saying the above outright, and hope you won't take it too personally, but again, I say it only to illustrate how very hard it would be to capture that "whole" with vector drawings. I know you even went to the trouble of creating custom fonts, etc., for the draw elements, and that is admirable to say the least. But what would the rest of us mere mortal, part-time people have to do to capture that "whole", if the full-time programmers and forum gurus are having such headaches?!?! ;-) Could someone theoretically do a vector HUD that looked almost exactly like the real (complex) one they're modelling? Yes. Would it be difficult? Yes. Would it be EXTREMELY difficult? Yes. Would it be "advantages not worth the disadvantages" difficult? IMO... yep.Scotthttp://forums.avsim.net/user_files/153003.jpg

[n4gix 4,947]

>Same principle. The distance between the lines on each of>those balls is going to be very different, but measure the>same arc.Pardon me for jumping in here, but it seems that you are both saying correct things from your own points of view... ;)Stick, consider this from a different perspective for a moment. A HUD is primarily a VISUAL reference, and secondarily an INFORMATIONAL reference...One of the chief benefits of a HUD is that from the pilot's eyepoint, the angle depicted on the pitch ladder should be precisely calibrated to represent that same arc angle in the outside view.That means, assuming the a/c is in level flight, that if there is a target at 12 o'clock and 10

[Guest Patrick_Waugh]

I have to agree with all the above with the possible exception of the eye angle through the HUD, but I suppose this depends on the HUD.The pitch ladders on the ones I have flown (AV-8B) weren't calibrated in the way you describe. The HUD is actually pretty darn small in comparison to the bubble of the cockpit.But I think mainly we were talking about different things.

[Guest ridgell]

oh goodie! code! i will see if your snippet is informative enough for me to get behind the wheel. i did get the thing working; shifting, rotating, etc. in bitmaps.@heading 60 <@heading 30 - /-/l3where l3 = (A:PLANE BANK DEGREES,radians) @heading will get stuffed into a reg. when i optomizenext dilema; where to put it? http://www.novelair.com/forum/(viggen movie link) looks like it rides between the 00 and -02 pitch lines

[Varmint007 2]

Hi Scott,Yes, you're correct in that the size of individual elements in my HUD are not the same as the real thing. For instance text is proportionately larger. However this is by design, and not a result of lack of information. The reason is that real HUDs are much larger and brighter than those which must be integrated into FS panels. One must consider the readability at the reduced scales, particularly in contrast to things like a bright FS sky which unfortunately must share the same luminosity as the HUD being modeled.If the HUD were fullscreen it would be much easier to remain true to the original proportions while maintaining readability. But IMO, it's just not readable otherwise. It's certainly not difficult to create font vectors which exactly match the RL counterparts.--Jon

[Guest jprintz]

ridgell,You may want to nose around this site: http://www.patricksaviation.com. There are many HUD videos on it, and I THINK I recall seeing a Viggen HUD video on there at some point, but am not positive.

[Guest ridgell]

thanks for the tip Scott.i am a big fan of Patrick

[phjvh 0]

Hi,I use very often something like:Your bitmap valuesbitmap1 Luminousbitmap1 Brightbitmap2 etc.your rotate valuesWorks perfect and saves a lot of code.Jan"Beatus ille qui procul negotiis..."

[Guest ridgell]

jancool thks.ahhhh.... where do you put the AXIS? ( it was for a masked image)make a super element and inclose it there?oh and thanks again!!!!!!!! searching a bunch of your posts, trying to make;%(@speed)%!03d!% %(@alt)%!03d!rotate, the dern Swedes again, the speed and alt read-outs run just above the hor.line (with the compass running just below) not a dawgawn thing is static on their hud. it all shifts and rotates. --i digress, after banging my head agaist a pivot wall, somehow i thought strings would use pivot like polylines do. i came across a post of yours helping someone rotate a string. AXIS...badda-boom i figured out how to drive tha vector car! you need 3 of these ( most ladder lines displayed at any one time) make a macro to decifer current pitch and %(@pitch)%!3d!%______________%(@pitch)%!03d! shifty shift %(@pitch 5-)%!3d!%______________%(@pitch 5-)%!03d! shifty shift %(@pitch 5+)%!3d!%______________%(@pitch 5+)%!03d! shifty shift rotate( i was compaining above that i never got enough snippets to figure out how a string ladder worked) 400 bit map code lines become 10 or in my bitmap hud closer to 1000 yiks.was glad to see you got 25 for the actual scale...same number i was useing, but i used the 'eyeball' method to get there not exactly high math...just played with it until the boat house stayed under the pitch line.

[n4gix 4,947]

Resurrected post to recover necroed XML script - Bill (N4GIX)

jancool thks.ahhhh.... where do you put the AXIS? ( it was for a masked image)make a super element and inclose it there?oh and thanks again!!!!!!!! searching a bunch of your posts, trying to make;<String>%(@speed)%!03d!% %(@alt)%!03d!</String>rotate, the dern Swedes again, the speed and alt read-outs run just above the hor.line (with the compass running just below) not a dawgawn thing is static on their hud. it all shifts and rotates. --i digress, after banging my head agaist a pivot wall, somehow i thought strings would use pivot like polylines do. i came across a post of yours helping someone rotate a string. AXIS...badda-boom i figured out how to drive tha vector car! you need 3 of these ( most ladder lines displayed at any one time) make a macro to decifer current pitch and

<String>%(@pitch)%!3d!%______________%(@pitch)%!03d!</String>	   shifty shift	<String>%(@pitch 5-)%!3d!%______________%(@pitch 5-)%!03d!</String>   shifty shift <String>%(@pitch 5+)%!3d!%______________%(@pitch 5+)%!03d!</String>   shifty shift  rotate

( i was compaining above that i never got enough snippets to figure out how a string ladder worked) 400 bit map code lines become 10 or in my bitmap hud closer to 1000 yiks.was glad to see you got 25 for the actual scale...same number i was useing, but i used the 'eyeball' method to get there not exactly high math...just played with it until the boat house stayed under the pitch line.