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View Full Version : Strange Pitch Movement in Camera Path



thracker
09-20-2015, 12:18 AM
Hi Everyone. I hope someone can help. I'm animating a camera to fly around a word like in the Marvel Studios fanfare intro. It seemed straightforward enough. However, I get this weird pitch change in between keyframes. The camera dramatically looks increasingly down until the midpoint between the keyframes, then looks back up, ending where I've set it at the second keyframe. If I place an additional keyframe in between, then I just get the same problem twice. I've looked at all the settings under Motion Options and everything seems fine. I've tried targeting the camera to a null, but it still happens. I've parented the camera to a null, then keyframed the null to travel around the word. The same thing happens and continues to happen even if I try to correct the weird pitch movement by keyframing the pitch of the camera. I've tried adjusting the curves in the Graph Editor. I've tried + and - values for tension, continuity, and bias (all three because I was desparate). I've tried changing all incoming curves to Hermite and then Bezier and adjusting, with no luck. The odd thing is, when using Bézier curves, when I select Pitch and adjust the handles, it changes the camera's banking. When I select Bank and adjust the handles, it also adjusts the camera's banking. Adjusting the Heading handles adjusts the heading. Nothing seems to adjust the pitch using Bezier handles. What is going on? It doesn't happen between all keyframes, just some. Is this some kind of gimbal lock situation? I didn't think it was as when I choose Rotate, all the circles around the camera are oriented differently. (Sorry for my lack of Lightwave vocabulary.). I couldn't find anything about this searching through the archives. Any ideas on what's going on? Using LW 11.6.

lertola2
09-20-2015, 09:35 AM
I am having a hard time picturing what you are talking about. Could you attach a scene that demos the problem? Are you animating the camera so that it passes close to looking directly down or up? If so the camera is going to flip over as it passes that point. You can parent your camera to a null and use the null to animate the pitch to avoid that I think.

thracker
09-20-2015, 11:28 AM
Thanks for replying lertola2. I'll try and post a scene file later today. The camera never comes close to looking directly up and down, so that's not it. Basically, think of it like this: the camera is just supposed to look straight ahead, for the most part, as it travels to the left from one keyframe to another. Instead, it increasingly looks down until it reaches the midpoint between keyframes then increasingly looks back up until it reaches the second keyframe. For example, imagine that the camera was going to fly in front of a person going from right to left, pointing ahead at the person's midsection the whole time. Well, it does that, except halfway through, the camera is looking down at the person's shoes, then looks back up to the midsection by the end. I already tried parenting my camera to a null and it didn't help. I'm so stuck here!

RebelHill
09-20-2015, 12:52 PM
its the key interpolation...


https://www.youtube.com/watch?v=jHdU9SYS7_U&list=PLTds3QePYrWGUd7fMuNAivIsORvpnKDqX&index=38

MonroePoteet
09-20-2015, 01:43 PM
If you hadn't targetted the camera at a Null, I'd say it was the overshoot settling and anticipation built into TCB splines. If the keys before and after the range where you have the problem do significant pitch changes, then the camera will overshoot from the prior key and settle, and then anticipate the subsequent key. I'd recommend that you select all the camera keys in the Pitch channel and set the Tension to 1.0.

For example, if your keys for H,P,B are (-45,-45,0), (0,0,0), (0,0,0) and (45,-45,0), between the two 0,0,0 keys it will dip down from the overshoot and anticipation. The heading will also do the same. Attached a sample scene, and if you examine the P and H channels in the Graph Editor, you'll see the phenomenon.

mTp

thracker
09-20-2015, 02:25 PM
Thanks RebelHill. I'll try FlattenHold although I'm not to hopeful. I've tried editing the pitch channel for the camera directly with no success. Again, the Bezier handles for Pitch and the handles for Bank both alter the camera's Bank for some reason. It won't allow me to edit the Pitch. But again, who knows? FlattenHold might surprise me. I'll post my results. Thanks again!

thracker
09-20-2015, 02:35 PM
Thanks for replying MonroePoteet. Yeah, I already tried TCB curves, setting tension to 1.0 with no luck. Thanks for attaching your scene. I'll take a look at it and see what I can learn. Thanks again.

thracker
09-21-2015, 01:49 AM
I've tried adjusting the curves in the Graph Editor. I've tried + and - values for tension, continuity, and bias (all three because I was desparate). I've tried changing all incoming curves to Hermite and then Bezier and adjusting, with no luck. The odd thing is, when using Bézier curves, when I select Pitch and adjust the handles, it changes the camera's banking. When I select Bank and adjust the handles, it also adjusts the camera's banking. Adjusting the Heading handles adjusts the heading. Nothing seems to adjust the pitch using Bezier handles.

RebelHill, I agree it's key interpolation. However, as I mentioned, the curves don't seem to be behaving. Why would the Bezier handle for Pitch affect the Bank of the camera. The Bezier handle for Bank also affects the Bank of the camera. Heading affects the heading of the camera. Why will no Bezier handles affect the Pitch?

MonroePoteet
09-21-2015, 07:27 PM
RebelHill, I agree it's key interpolation. However, as I mentioned, the curves don't seem to be behaving. Why would the Bezier handle for Pitch affect the Bank of the camera. The Bezier handle for Bank also affects the Bank of the camera. Heading affects the heading of the camera. Why will no Bezier handles affect the Pitch?

Sounds like gimbal lock to me. Trying to reproduce the Marvel motion path myself with the text modeled down the Z axis (MARVIN in my case, no copyright issues here! :)), I got gimbal lock as the camera moves past the top of the "M" toward the "A". So, I'd guess you have the overshoot / anticipation on the Pitch channel, but can't fix it due to gimbal lock. Here's a sample scene. If you use Perspective view ("4") with the Camera selected ("C") and its Rotation channels selected ("y"), you'll see the gimbal lock at frame 60. Trying to change the Pitch only affects the Bank.

If you modeled your text down the Z axis, you may have the same problem. Maybe try rotating your text so it points up the Y axis to see if you can avoid the gimbal lock.

mTp