Keying animations?

Xsi
1

scenerio:
in a 100 frame animation i am animating glow intensity for the following effect:
set key at frame 1 intensity = 0
set key at frame 10 intensity = 0
set key at frame 15 intensity = 8
set key at frame 85 intensity = 8
set key at frame 90 intensity = 0

the desired effect:
is that there should be a glow that fades in to intensity 8 by frame 15; intensity stays at 8 until frame 86 where it fades out.

the actual effect:
the glow fades in and continues to intensifiy until around frame 50. then it gradually comes back done so that by frame 85 it's back at 8. then it fades out the rest of the way.

the question(s):
why does it arch light that? how do i achieve the desired result? this happens whenever i key things (parameters, transformations, etc).

thanks,
pd.

2

hi!
this has to make with the interpolation between the keys..
when u have 2 keys that have the same value the nature of the spline interpolation makes that "segment" a curved one instead of a linear one, so your animation "accelarates" or the opposite between these 2 keyframes.
if u have XSI 2.0 go to file>user preferences and go to the animation part of the window that pops up..
on the right side under the "default slope orientation constraint" check the plateau radio button..
now when u have 2 keys with the same value the segment between thhese keyes will always be linear..
u can always change the interpolation manually by selecting the key and changing it's interpolation to linear , or using the slope handles..
hope this helps
george

3

excellent, excellent, excellent!

thanks