#Weird camera roll?
10 messages in this thread
I'm moving a camera in the keyframer and at a point where the camera and the
target are lined up, I get a 180 degree flip that I can't control! This is
driving me nuts….any solutions? Brent Bonet – POP! Multimedia Atlanta
Brent, You're problem with camera roll is due to something known as Quaternion
mathematics, which nearly all 3D programs use. You are experiencing what's
known as a singularity – the poles of 3D space. Ask GaryY for a more indepth
explanation of what that really means. 🙂 You can fix it by either adjusting
your camera slightly so that it's not directly over the target. I believe the
only time that will happen is when the camera is directly over it's target as
seen from the top view. If you can't do that you can link you're entire scene
to a dummy and rotate it 90 degrees (damn what's the Alt combo for a degree
sign). This should work also, but I've had problems with it. I think it's
simplest to adjust your camera, but you can experiment.
DM
Yeah, I thought it must have something to do with the way 3DS handles it's
world…I just ended up keyframing the hell out of the roll setting in that
area. Not good for nice ease in and outs but…..
Brent Bonet – POP! Multimedia Atlanta
Brent:
Man, I hate this one, too. You've fallen into the quaternion abyss. If it is
possible you can avoid this problem (forced camera roll at the poles) by
rotating your whole model and camera, et. al. 90 degrees. Link them all to a
dummy in the keyframer and then rotate. This problem is a killer in lots of
architectural work when you want to be poised directly over a site plan and
then swing down to a view which would be almost equatorial. Allowing a camera
to ignore this roll has made it to the wish list several times. Hope you can
work around it.
Bob
Suppose you could eliminate it, though. Consider facing an object, and then
flying over it and looking down. If you continue over the azimuth, your camera
is now upside down — and you hit your head on the ground when you land!!
At some point you need to roll to remain upright. This is the whole purpose of
quaterions (all of this I'm sure you already know). My point is, how would you
handle the "landing upside down situation?". And why not just let 3DS handle
it by keeping the camera about 3o – 5o from the vertical. BTW, ALT 167 for
that degree symbol. 😉
— James — Choreo Motion —
>> BTW, ALT 167 for that degree symbol. 😉
James, I was actually looking for 90x not 90' (Alt 248) 🙂 So which one is
right?
DM
> James, I was actually looking for 90x not 90' (Alt 248) 🙂 So which one is
right? <
I think you are right. ALT 167 works in Ariel (True Type), but ALT 248 seems
more consistent across most fonts.
. . . learn something every day . . .
— James — Choreo Motion —
James:
/_______________________From your message________________________\\
Suppose you could eliminate it, though. Consider facing an object, and then
flying over it and looking down. If you continue over the azimuth, your camera
is now upside down — and you hit your head on the ground when you land!!
__________________________________________________________________
This is exactly the PREDICTABLE behavior that I desire!!!!!!
/_______________________From your message________________________\\
At some point you need to roll to remain upright.
__________________________________________________________________
No way, this may be true for some but I want to override this 'feature' all the
time.
I want the camera to move ONLY when I tell it to and ONLY in the manner that I
ascribe. Forcing this roll may be a desired effect in some circumstances but
NOT in all. I am just asking for the ability to lock the effect for the times
when it could be desired.
Bob
I certainly understand your request for an override. But do you realize how
difficult keyframing would be without this automated roll caused by
quaternions?
Any relative angular rotation of CameraN.target about CameraN would create an
abnormal tilt to the view, except for when both the camera and target remain
contained in the horizontal plane xz (in other words, almost always).
Still, a simple override would be nice at times. I guess that it's such a rare
problem for me that the "rotate the whole scene" workaround is OK for me.
— James — Choreo Motion —
Title: Camera flips 180 degrees; Workaround for Gimbal lock…
Description:
Tthe 3D Studio camera will occasionally appear to turn everything upside down,
as if the camera has been suddenly flipped 180 degrees. The view in the camera
viewport will suddenly display images that are upside down and the camera does
not have any keyframe information which would explain this flip. The
workaround for this is simple.
In the keyframer, link everything in your scene to a dummy object on frame 0.
Rotate the dummy object 90 degrees. This will shift the entire animation to an
orientation in which the camera will never pass over a singularity at the
poles.
Note: This singularity is an artifact of quaternion mathematics which was
originally developed in the 1800's. All high end animation systems use this
form of math for smooth keyframe motion. Quaternion mathematics is discussed
in John Vince's book, 3D-Computer Animation, published by Addison-Wesley.