View Full Version : Urgent advise on Motion Path

03-03-2007, 03:05 PM
Can someone please tell me why my motion path gets all knoted up? I am not kidding, the path has these little loops in it when I load into layout. I tried increasing the number of frames, scaling keys in scene editor. I have spent way to long on this. I am doing a simulated aerial flyover of a proposed roadway approx. 30 miles long. I just want the camera target null to follow the roadway. My path created in modeler has approx 200 points. Is this to many points to use in a lw curve for export as motion path? Folks, I am really getting desperate. I really dont want to manually key-frame each incremental segment of my intended path but that is what it is about to come down to.

03-03-2007, 03:30 PM
i don't know exactly but perhaps have to do with the number of frames and number of control points in the path...
seem to recall number of control points corresponds either to number of frames or seconds and you have to make the conversion correctly...
ie consider rebuilding your motion path using rail extrude using a single point poly and number of knots corresponding to the number of frames(or seconds) of animation


03-03-2007, 03:45 PM
Thanks katsuy for the fast response. I am gratefull. Is'nt rail extrude for creating a surface along a path? and I believe that path would be made up from a spline. I dont know what a single point poly is. A poly to me is a line segment or a polygon surface. Thanks though, if you have any other idea please let me know. I will try again using the info in modeler or statistics, I forget which one told me that I have 200 points in my path curve. I will try the control points must equal frame number method you suggest.

03-03-2007, 07:36 PM
ok sorry not to be more clear
i just did a quick check and seems like every control point in the path(spline) gets divided into 5 frames so if you have a spline motion path with 3 control points it will be 10 frames long...
if you rail extrude a point poly(ie one point poly) you can use it to build your spline from it.

03-03-2007, 08:36 PM
katsuy, I cant try it right now but when I get back to my work I will. Could I use the lw spline draw to do this, Im thinking I could use info button in modeler to let me know how many control points there are in my spline, then set the frames acordingly ie: say my spline or curve has 100 control points, then I would need to have 500 frames set in layout to complete the 5 frames per control point criteria. Thank you very much for helping me on this, I will let you know how it comes out.

03-03-2007, 08:38 PM
Each point on your spline represents 5 frames in layout. Its easier IMO to determine how long the animation needs to be and then create a spline with the appriate # of knots.
Ive had to scale motion paths created this way without things messing up so its hard to say whats causing it.
You could also just load the spline into layout and use the curve constraint plugin.
You can rail extrude a single point polygon along a spline. Then select a couple of the point and use the select loop command to select all the points. Use the make spline command (ctrl + p) to make a new spline and delete everything else.

03-05-2007, 06:23 PM
Everything is fine except for jerkiness. My camera is parented to my target null which is useing the curve constraint. Curve constraint is applied to my target null, camera is also targeted at the target null. I need a more fluid spline I believe. Is this why you were telling me to create a one point poly useing rail extrude? Would that create a spline with knot to knot distance being equal throughout the length of the spline?

03-05-2007, 07:54 PM
if by jerkyness you mean it accelerates and decelerates, yes you can do the extrude the one point poly as clearly explained by splinegod....it will ensure that the camera/null will move in constant speed along the curve
are your little loops gone?? becaue that would be the first thing to sort out


03-05-2007, 10:04 PM
Yes Katsuy, those blasted little loops are gone thanks to you and Splinegod. I went ahead and used curve constraint on the camera as well, it just works out a lot better to have a designated path for camera and another for camera target. The one point poly works great for spline path. Again, thanks to both you and Splinegod for taking the time to share your expertise. :thumbsup: