My first question, a tricky one!?

[Signal2Noise]

Well, I'll have to recreate your scenario to see what a possible solution could be for your specific problem. However, off the top of my head I can offer an alternate way of handling the camera.

Use two cameras. You have the one you created up to frame 36. Then create a second camera to handle the vertical section. This way you don't have to worry about the camera "flipping" on you unexpectedly. In order to render the scene out with two cameras you would render them separately then use Video Post to stitch them together seamlessly. I believe this will still achieve the effect you're after.

Thinking as I was typing the above suggestion: You could also create a Dummy Helper to attach the one camera to and animate the Dummy to follow the path which in turn will move the camera. This process should also prevent the camera from flipping on the vertical.

Hope this helps! If I think of anything else I'll get back to ya :thumbsup:

[halo]

first i'd look at your path closely because it may be you have a twisted spline or not enough points, which is why it may work with the path cut.

attaching a dummy then attaching a camera to that is good practice and allows more flexability

[Ls3D]

Isn't this that old quaternion (kw-tûrn-n) math issue,..

Seems the Euler controller can handle this, but I'm short on sleep at the moment so don't bet the farm on it. I may have used a dummy on the path a few frames ahead and a look at controller to fix this problem as well.

Anybody not half asleep got the fix?

-Shea
www.Ls3D.com

;)

Any number of the form a + bi + cj + dk where a, b, c, and d are real numbers, ij = k, i2 = j2 = -1, and ij = -ji. Under addition and multiplication, quaternions have all the properties of a field, except multiplication is not commutative.

[and3x]

Thank you so much for trying to figure this one out!

I have tried to link the camera to a dummy with the path constraint applied to it, but with no luck. This tip regarding the Euler controller is something that i honestly dont know anything about since i am quite new to max.

If someone would go so far as wanting to have a quick look at the file you can find it here:

http://w1.874.telia.com/~u87412770/track3.max

Take care // and3x

[Ls3D]

OK, so I've had some dinner and fixed your problem...

Just enable 'allow upside down' on the path parameters.

Here is an R3 file should you wish to have a peek:

http://www.ls3d.com/FTP/Ls3D-cam-upside-down.zip

-Shea
www.Ls3D.com

:applause:

[and3x]

Hi Shea, It is a little more complicated i am afraid. I have had "allow upside down" on and off from time to time, but it just wount do it on this type of path. I looked at your file and found the same kind of testing that i also managed to get working.

It is just that my loop is not intersecting itself when it its done, it is an "open" loop, not a circle if you know what i mean (starting on the left and finishing a bit to the right from the cam view)?
Last but not least you must try adding some turns after the loop, thats where the real hassle starts. ;)

Here is your file (re-saved in 5.1) with some adjustments to resemble what it is i am trying to do more.

http://w1.874.telia.com/~u87412770/camera-upside-down._2.zip

[Signal2Noise]

Did you try the multi-camera method yet? I'm sure that'll work.

[ivan iliev]

Hi and3x,

Rotate the camera 1° on it’s local ‘x’ or ‘y’ axis, and try again.
Sometimes this helps.

ivan

[Ls3D]

Hi &3x,

I tried creating a new roller coaster path and I see what you are talking about, really it is a reminder of a familier problem - one that exist across the various 3D apps. For example search 'quaternion' or gimble lock here and on other 3D forums and you will get some results.

Sig2Noise's workaround is sounding more resonable,.. could have a problem with motion blur though.

So I've got to bail - and work on my sound effects - goog luck and let us know what you work out.

-Shea
www.Ls3D.com

:cool:

[EricChadwick]

Weird. Follow and Allow Upside Down work great here. Didn't download your file, but made an open path and a free camera, and it works fine. v5.1

[and3x]

Thank you guys, this forum has really proved itself in being really helpful, altough my problem still exist. It isnt the end of the world tough, i was just fooling around while practicing max, so it is not going to spoil any 10 000 $ worth of work. I will either have a go at signal to noise´s double camera solution, or just skip the loop.

It is however kind of frustrating to let it go, since solving a (so seemingly easy?) problem always leave you in some sort of comforting sensation. ;)

posm:

It is really cool that you gave it a go, and maybe you just didnt encounter any problems. What i mean regarding the "open loop" is that when the camera enters the loop it is not supposed to be in the same position (x-wise) as when it exits the loop. The loop is supposed to go in a kind of spiral. I dont really know how to explain it better, but anyhow that is (in addition to having more curves after the loop) when the problems start.


Thank you again.

[gaggle]

It sounds to me like you could use an "up node" for the camera. I'm not sure how to do it in MAX, but with Maya you can create a camera that has a target and an up node, so you can tell the cam not just where to look but also what z-rotation it should keep.

Maybe you can add an Orientation constraint to your cam? Play with the settings and see if you can constrain the camera only to which way it rotates around itself, but without also constraining where you want the camera to look.
OR.. or, you make a Targeted Camera, and add an Orientation constraint, and that might do the trick since that might not mess up what the camera looks at (what it looks at should be the purpose of the target-dummy)

Hm.
I'll stop rambling now :)

[TapioKa]

Could be Gimbal lock, if your camera target passes almost vertically downwards. There are several solutions if that is the case.

The best approach is to make a target camera, and link the camera and target to the dummy. Let the dummy handle the path.
If your camera flips anywhere along the way you can keyframe the target to remove the gimbal lock flipping. You will recognize Gimbal lock because it usually flips 180 degrees.

Also make sure you have high steps in your path spline. It will make the animation path smoother.

Hope that helps.

[magicm]

TapioKa : Raising the number of steps makes the path smoother, but the path animation stays exactly the same..
Path controllers always use optimal interpolation, so the 'steps' value is ignored.

and3x : Are you using a Free Camera on the path? I think a Target cam won't work.. My tests work fine:
- draw path in front view ( just a line with a loop in it )
- create a free camera
- assign a path-controller and pick the path
- check 'Allow Upside Down'

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