CGTalk - Xpresso JibCAM

akport

11-03-2007, 03:55 PM

I created my own camera rig a while back using Xpresso and now revisiting it. Overall it works well but I'm having two issues. First, when I tilt 90 or 270 degrees, the camera goes into a spin. Second, the camera gets a little wonky when it comes to updating in the viewport. This is especially noticeable when rewinding. I usually have to refresh by moving off a frame and back to get it to the right position. I've tried adjusting the priority of the Xpresso to no avail.

The file is attached if anyone wants to look at it or use it.

Thanks,
Adam

flingster

11-03-2007, 05:34 PM

cheers for sharing..:thumbsup:

C.Smith

11-05-2007, 01:42 PM

You may be running into the same problem I had when making MoCam. Where the camera will loop around when past 180degrees of motion.

Lennart helped me solve this. Open a COFFEE node inside of Xpresso and use the 'minimizeAngle' function. (Check the SDK for details).

If you want to see how it's done in MoCam, download here:

http://sugarfilmproduction.com/CSTools.zip

You will have to look inside any one of the "MoBlend" nodes and you'll see a COFFEE node there using 'minimizeAngle'.

akport

11-06-2007, 03:33 AM

Thanks for the tip on COFFEE. I'll have to dig a little deeper to figure out where it all goes. I've been a big fan of your tools. Any idea why my screen updating is often out of whack and not smooth?

Thanks,
Adam

C.Smith

11-06-2007, 10:22 PM

unless i missed it, this forum needs a delete messages function. Read post below.

C.Smith

11-06-2007, 10:23 PM

I only had a few moments to play with it. I don't remember it being laggy for me. But I did see your camera flipping.

As a small side note. May I suggest using a 2D vector box for your cam pan and tilt as well as your gimble X and Z. It may be more intuitive to the user than individual sliders.

I also just noticed you use a target. I'm pretty sure that's where the flipping is coming from. You may want to kill the target all together. If all it's doing is keeping the camera from rotating with the arm, then just link the position to the null at the end of the arm rather than parenting the cam to the arm. Then it will keep the same rotation you left it in all the time from your pan/tilt controls.

Although it's minor, if you're trying to simulate a jib, I would call it "Z Axis" instead of "up vector". Because when you rent a jib and you want the camera to bank/roll/dutch you ask for a 'Z Axis' head.

akport

11-07-2007, 01:18 AM

I'm starting to think that the z-axis issue is responsible for all the issues. In the viewport axis in the camera view, I see the z flipping around even when the camera isn't doing much and it is responding correctly. There is probably some wonky math going on it there.

Thanks a million for the time and tips.

- Adam

C.Smith

11-08-2007, 01:29 AM

I decided to bang a quick jib out to show what I speak of:

http://sugarfilmproduction.com/jib.zip

CGTalk Moderation

11-08-2007, 01:29 AM

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.