Dude, give it up. You are wrong. Accept it and move on with your life.
On Sun, 2004-01-11 at 09:13, Alan King wrote: > Jon Berndt wrote: > >>Jon Berndt wrote: > >> > >> > >>>Model Reference Point (MRP): This is the reference point that is agreed > >>>upon by both the aircraft modeler and the 3D model builder. > >> > >>I'd vote for calling it the "Visual Model Reference Point" because the > >>term model can still be used for the 3d model and he flight model. > >> > >>Erik > > > > > > True. > > > > Note this fact. If you have the CG point as the reference, then scale > matters very little to the motions of flying. Only the point reference makes > the models match reasonably well. You still need a distance measurement to know > the scale and work out CG shifts, where the nose, wheel, and tail really are, > etc though. Even the control forces off. But the motion point is not, for both > rotation and translation. > > You aren't just using the nose point. No matter how much you trick > yourselves into saying that you're only using the nose, and just 'fixing it', > you are really providing a distance reference back to another point. It takes > one point with full orientation, and another point to completely match two > reference frames. There is no way to get around that fact. What you are really > doing is having the nose point and a difference reference, and then working > everything out from that bringing everything into alignment. That includes most > importantly for visual motion to FDM motion match the CG. > > If you look across all your models of all scales, you will see that your > adjustments all bring the CG point of the visual model to the CG point of the > FDM. The CG to nose distance will be different, but that's in the offset > combined with whatever the FDM does with the offset to find the CG point. > > > Take all of the models. Put all of the nose points at exactly the same spot. > put the FDM nose point there. Note that you have a range of CG's based on how > large the plane drawing is. And your 'nose fix adjustment' is the distance to > some other point. Then your FDM works out the CG point of each size model from > that other known adjustment and your CG is in the right place in both models. > We already put all the nose points into one spot. If your alignment system only > needs the nose point to match in the FDM and the visual model, then set the FDM > nose to a known point, put all the visual nose points there, and your models > will all work no matter what size. This doesn't work, even though all of your > nose points are now correctly known. It doesn't work because you need a nose > point known, plus another number to some other reference point. This other > reference gives you scale, and then put all other points in their place. Most > importantly to visual motion, it lets you put your CG where it goes on the > visual model. > > That was my original point, it is impossible to have just the nose point on > the visual model and not have anything else and have everything match regardless > of scaling between the FDM and the visual. You have to have some other > reference fix, that lets your FDM bring it's CG into alignment of where it > should be on the visual model. That you are hiding it from the model creator so > they don't have to find the CG of the visual model is a great idea. That you > are hiding it from yourselves though by saying you're 'fixing the nose point' > isn't as good. You're sliding everything around with this adjustment, not just > the nose point. And while it brings everything into line, the single most > important thing to how the model moves is getting the CG correct. You don't > have some arbitrary fixed point on the nose of both models that makes everything > line up. You have a fixed point on the visual model only. You then move it > around on your FDM model with your adjustment, until the CG is where is should > be for the visual model so the motion looks correct. If you double the scale of > the picture, you have to adjust your nose to CG distance through your > adjustment, even if that uses some other common reference point to get the CG in > the FDM. Your adjustment is fixing where the nose should be, relative to some > other point, so that that other point is where it should be, so that the CG is > now also calculated in the right position in the visual model. > > You don't have a 'nose point does everything' system. That adjustment isn't > some minor little tweak to your system. That 'adjustment' carries every bit as > much weight in aligning the system as the nose point. Using the nose point > first lets the model creator make the model without reference to scale, which is > great. But it just means that someone on the FDM side is fixing the scale later > through the adjustment, not that the nose point is the only thing and nothing > else matters. That adjustment is just as critical to the alignment of the > systems as the initial point. It takes both, the nose point isn't 'it' like > some of you have tried to imply. There was something else to your system, which > there had to be to bring the FDM and the visual model frames into full > alignment. No single point fix at the nose or even the CG can completely align > two frames. > > Alan > > > > > > > _______________________________________________ > Flightgear-devel mailing list > [EMAIL PROTECTED] > http://mail.flightgear.org/mailman/listinfo/flightgear-devel -- Tony Peden <[EMAIL PROTECTED]> _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
