How about having a small xml file for each 3d model, telling at what
offset the tip of the nose is?
Then, you could use the same aircraft definition file with a different
3d model without messing around with offsets too much...
--Brandon
___
Jim Wilson wrote:
Besides in my flight modeling methodology deficient mind, it kind of makes
sense that position data is tied to a fixed location on the aircraft.
Working relative to a fixed location (whcihc could be inside the
airframe, but doesn't need to be) works quite will I must say.
Erik Hofman writes:
But then again, how about the aero refference point? This is
single the location in the aircraft that can be used to describe
the aircrafts flightpath because all other locations will rotate
around it in flight. This point has to be known by 3D modellers
already
David Megginson wrote:
Erik Hofman writes:
But then again, how about the aero refference point? This is
single the location in the aircraft that can be used to describe
the aircrafts flightpath because all other locations will rotate
around it in flight. This point has to be known by 3D
On Mon, 2002-12-16 at 04:07, Erik Hofman wrote:
David Megginson wrote:
Erik Hofman writes:
But then again, how about the aero refference point? This is
single the location in the aircraft that can be used to describe
the aircrafts flightpath because all other locations will
Tony Peden wrote:
To the best of my knowledge (whatever that might be ;-) ) the CG moves
around, but the aero refference point is steady? Jon, Tony?
No, it doesn't, but you can't exactly walk up to the aircraft and point
at it either.
Hmm, maybe I've been busy with JSBSim too much lately.
Do
To the best of my knowledge (whatever that might be ;-) ) the CG moves
around, but the aero reference point is steady? Jon, Tony?
yawn ... wow lots of email this morning ... I just woke up and already it
looks like I am going to have to *think*
Erik is right. The aero reference point is the
On Mon, 2002-12-16 at 04:29, Erik Hofman wrote:
Tony Peden wrote:
To the best of my knowledge (whatever that might be ;-) ) the CG moves
around, but the aero refference point is steady? Jon, Tony?
No, it doesn't, but you can't exactly walk up to the aircraft and point
at it either.
David wrote:
As others have mentioned, though, that point moves around during
flight depending on how the plane is loaded, how much fuel you've
burned, whether you're subsonic or supersonic, whether the flaps
are extended, whether you've just dropped skydivers or a bomb,
etc. etc. In a
Jon Berndt writes:
We all know that we can rotate the 3D model correctly, but the issue is
the translation. JSBSim reports the location of the CG, which is NOT the
translation for any point on the aircraft, but ONLY the CG.
So, the solution is that JSBSim (and other FDMs) could report the
On Mon, 16 Dec 2002 13:29:18 +0100,
Erik Hofman [EMAIL PROTECTED] wrote in message
[EMAIL PROTECTED]:
Tony Peden wrote:
To the best of my knowledge (whatever that might be ;-) ) the CG
moves around, but the aero refference point is steady? Jon, Tony?
No, it doesn't, but you can't
Right. In other words if the nose is the 3D model origin, it's
altitude is
made that of the CG (as reported by JSBSim). The aircraft is angled up
for takeoff and the nose is way down near where the wheels should be and
the
rest of the model is below the surface.
To throw another wrench
On Mon, 16 Dec 2002 07:14:59 -0600,
Jon Berndt [EMAIL PROTECTED] wrote in message
[EMAIL PROTECTED]:
David wrote:
As others have mentioned, though, that point moves around during
flight depending on how the plane is loaded, how much fuel you've
burned, whether you're subsonic or
--- Norman Vine [EMAIL PROTECTED] wrote:
Jon Berndt writes:
We all know that we can rotate the 3D model correctly, but the
issue is
the translation. JSBSim reports the location of the CG, which is
NOT the
translation for any point on the aircraft, but ONLY the CG.
So, the
FWIW, I still think the location should be configurable by the 3D
modeler in the FG xml files. FG would pass that info to the FDM and
it would return the appropriate position or FG would do the calcs
itself. The wind doesn't seem to be blowing that way, however ...
Actually, I thought of
Tony Peden wrote:
The point we pick need not have any particular signifigance (we can
calculate a lat/lon/alt for anyplace relative to the aircraft), so why
should we pick a point which requires explanation and/or instruction on
our part and more work on the part of the 3D modeler.
The nose
Jon Berndt [EMAIL PROTECTED] said:
Right. In other words if the nose is the 3D model origin, it's
altitude is
made that of the CG (as reported by JSBSim). The aircraft is angled up
for takeoff and the nose is way down near where the wheels should be and
the
rest of the model is below
Well, to rotate the aircraft realistically the refference point should
be known by the 3D modellers, but that aside.
The rigid body rotates about the CG, not the aero ref. pt.
smime.p7s
Description: application/pkcs7-signature
Jon Berndt [EMAIL PROTECTED] said:
When I think about this for long enough, I keep coming back to this: that
if the nose is taken to be a common reference point between the FDM and
the 3D model, then we (FDM) can simply provide the location of the Nose
Reference Point (NRP) and the FGFS side
Jon Berndt wrote:
Well, to rotate the aircraft realistically the refference point should
be known by the 3D modellers, but that aside.
The rigid body rotates about the CG, not the aero ref. pt.
Even when in motion?
It seems to me there would otherwise be no need for a refference point.
Erik
On 12/16/02 at 9:36 AM Jon Berndt wrote:
Well, to rotate the aircraft realistically the refference point should
be known by the 3D modellers, but that aside.
The rigid body rotates about the CG, not the aero ref. pt.
What about rotation (the taking-off one)? Surely in that case it rotates
--- Erik Hofman [EMAIL PROTECTED] wrote:
Jon Berndt wrote:
Well, to rotate the aircraft realistically the refference point
should
be known by the 3D modellers, but that aside.
The rigid body rotates about the CG, not the aero ref. pt.
Even when in motion?
In the FDM's (all of
On Mon, 16 Dec 2002 15:56:13 +
David Luff [EMAIL PROTECTED] wrote:
What about rotation (the taking-off one)? Surely in that
case it rotates about the axles?
Cheers - Dave
Well ... sort of. In real life, yes, the gear is a pivot
point. However, in the FDM sense, the ground isn't really
On Mon, 16 Dec 2002 15:30:31 -
Jim Wilson [EMAIL PROTECTED] wrote:
Yes and we already have that capability. What we don't
have yet is a way to
offset what the chase view is looking at, but that won't
be a problem.
So, being supplied with the Nose Ref Pt. lat/lon/alt won't
give you
Rex du Pont wrote:
I've been watching this discussion for about a week. I am using the JSBSim
model on a
real airplane development project, to give you some background.
Seems to me that the question is about how to make a 3D model look right
from outside,
probably from a distance of several
On Mon, 16 Dec 2002 11:43:11 -0500
Rex [EMAIL PROTECTED] wrote:
Rex du Pont wrote:
Seems to me that the question is about how to make a 3D
model look right from outside,
probably from a distance of several wingspans away. In
that case, you do not have to be precise
about the congruence of
Arnt Karlsen writes:
..I like David M's proposal on FAA type datum points, those are
available for all FAA-certified planes, and as we learn more,
likely a good starting point for a datum FAQ for aero and 3D modellers
of the not-yet/no-way!/non-FAA aircraft.
In the end, it doesn't
Jon Berndt wrote:
Also, Andy: which point does YASim provide to FGFS? Is it the CG, or
some other point?
It provides the coordinates of the origin, be that the nose or
centroid or FAA reference point or whatever.
Going back into hiding now; wake me up if you need me to move the
origins. :)
Tony Peden wrote:
--- Erik Hofman [EMAIL PROTECTED] wrote:
Jon Berndt wrote:
Well, to rotate the aircraft realistically the refference point
should
be known by the 3D modellers, but that aside.
The rigid body rotates about the CG, not the aero ref. pt.
Even when in motion?
In the
Erik Hofman wrote:
Jon Berndt wrote:
Well, to rotate the aircraft realistically the refference point should
be known by the 3D modellers, but that aside.
The rigid body rotates about the CG, not the aero ref. pt.
Even when in motion?
It seems to me there would otherwise be no need
David Luff wrote:
Jon Berndt wrote:
Well, to rotate the aircraft realistically the refference point should
be known by the 3D modellers, but that aside.
The rigid body rotates about the CG, not the aero ref. pt.
What about rotation (the taking-off one)? Surely in that case it rotates
Jon S Berndt [EMAIL PROTECTED] said:
On Mon, 16 Dec 2002 15:30:31 -
Jim Wilson [EMAIL PROTECTED] wrote:
Yes and we already have that capability. What we don't
have yet is a way to
offset what the chase view is looking at, but that won't
be a problem.
So, being supplied with
Andy Ross [EMAIL PROTECTED] said:
It is true that there is an *illusion* that happens when you look at
a point far from the aircraft's c.g. which makes the airplane look
like it is not rotating correctly. But this is an illusion; what is
really happening is that the *viewpoint* is moving.
On Mon, 16 Dec 2002 18:41:50 -
Jim Wilson [EMAIL PROTECTED] wrote:
Yes and no. It should greatly improve the situation as far as keeping the
gear above the pavement in an external view. The other issue is the one
I described before where it looks odd because the camera tracks the nose
On Mon, 16 Dec 2002 14:19:16 -0500
Norman Vine [EMAIL PROTECTED] wrote:
Erik Hofman writes:
The nose is something that everyone can instantly
understand and
locate.
coughUFO, helicopter, balloon, parachutecough
he he :-)
Smart a$$e$. ;-)
So, where's the bounding box for these items,
Tony Peden writes:
The point we pick need not have any particular signifigance (we can
calculate a lat/lon/alt for anyplace relative to the aircraft), so why
should we pick a point which requires explanation and/or instruction on
our part and more work on the part of the 3D modeler.
The
--- Andy Ross [EMAIL PROTECTED] wrote:
Erik Hofman wrote:
Jon Berndt wrote:
Well, to rotate the aircraft realistically the refference point
should
be known by the 3D modellers, but that aside.
The rigid body rotates about the CG, not the aero ref. pt.
Even when in motion?
--- Norman Vine [EMAIL PROTECTED] wrote:
Tony Peden writes:
The point we pick need not have any particular signifigance (we can
calculate a lat/lon/alt for anyplace relative to the aircraft), so
why
should we pick a point which requires explanation and/or
instruction on
our part and
Jon S Berndt [EMAIL PROTECTED] said:
This is exactly the issue: as we all know, the rotations
are fine (a rotation is a rotation - the *orientation* of
the vehicle always ends up correct). It's the translation
issue that is cloudy. I think what we will do (and I think
Tony is agreeable
On Mon, 16 Dec 2002 20:17:43 -
Jim Wilson [EMAIL PROTECTED] wrote:
coordinate system is:
X positive aft
Y positive right
Z positive up
Sounds good.
Good.
Not sure what visual cues you are looking for. I would be hesitant to do a
translation that would have the pilot's head bouncing
Norman Vine [EMAIL PROTECTED] said:
xorig = fuselage length / 2
What if tail surfaces extend beyond the fueselage?
yorig = wingspan / 2
Ok got that.
zorig = highest point / 2 usually top of tail
Is that with gear up or down?
obvious enough for me :-)
Main Entry: 1cen·ter
Jon S Berndt [EMAIL PROTECTED] said:
main gear touchdown, but the cockpit sure will. Again -
this may be already being done correctly, but I worry
because you say that the pilot eyepoint information is not
being used.
Ah ok. Yes, that probably is a problem now because we are using the
Jon S Berndt wrote:
Well, with proper agreement and reference point, we can make this
perfect. There's just some communication and cooperation needed for a
little while, and I think we are nearly there.
Yes. I think several people are unclear about how this will work, and
have concerns like
On Mon, 2002-12-16 at 07:24, Jon Berndt wrote:
FWIW, I still think the location should be configurable by the 3D
modeler in the FG xml files. FG would pass that info to the FDM and
it would return the appropriate position or FG would do the calcs
itself. The wind doesn't seem to be
Julian Foad [EMAIL PROTECTED] said:
- Someone would modify the function that updates the Flight Gear scene
graph so that it puts the model geometry at the right position, by
transforming from position of nose to origin of geometry (which will
be different for each aircraft geometry model).
On Mon, 2002-12-16 at 10:26, Erik Hofman wrote:
Tony Peden wrote:
--- Erik Hofman [EMAIL PROTECTED] wrote:
Jon Berndt wrote:
Well, to rotate the aircraft realistically the refference point
should
be known by the 3D modellers, but that aside.
The rigid body rotates about the
Jon Berndt [EMAIL PROTECTED] said:
JSBSim reports the lat/lon/alt of the current CG. We know the relative
locations of other points, but do not calculate the lat/lon/alt of those. I
don't know who should calculate those things.
Ah ooo..hmmm...see the cg related message I just sent. This
I really don't understand the requirement as to having the origin
at the same location for all the FDMs.
That's not necessarily true. The requirement would be that the FDMs use the
coordinate system that they need to use, but publish a known point on the
aircraft in its (the FDMs) frame.
Jon Berndt
I really don't understand the requirement as to having the origin
at the same location for all the FDMs.
That's not necessarily true. The requirement would be that the FDMs use the
coordinate system that they need to use, but publish a known point on the
aircraft in its (the
Jon Berndt wrote:
I really don't understand the requirement as to having the origin
at the same location for all the FDMs.
That's not necessarily true. The requirement would be that the FDMs use the
coordinate system that they need to use, but publish a known point on the
aircraft in its (the
Jon Berndt [EMAIL PROTECTED] said:
This is exactly what I've been pushing for in that last day or two.
FWIW it makes the most sense to me to have the origin at the center of
the bounding sphere of the model
I'm not arguing that this doesn't make sense, BTW, just that it is ambiguous
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