Struggling with IPO Curve

I’ve set up a simple scene and have a camera following a path through it.

I want to have the camera slow down and speed up at various points throughout the scene and so have been trying to work with the IPO curve.

Unfortunately, I can’t understand the curve. Can anybody point me to some information on the meanings of the values of the curve graph and how to place keypoints on the curve so they appear in the places I want them to appear on the camera path?

All my attempts so far have resulted in erratic speed changes and the camera sometimes not reaching the end of the path.

Thank you.

http://wiki.blender.org/index.php/Manual/Ipo_Types

Thank you for the information. I must still be misunderstanding this idea.

When I select a path and switch to the IPO screen, a curve exists between two points. The point on the far right is at 230, which I believe means I have 230 frames in the animation.

If I move that last point beyond 230, the camera on the path never reaches the end.

As I understand it, the default curve is the speed set for a smooth animation.

If I set the curve to linear and decrease the angle of the line for a slower animation, the end of the line no longer reaches the 1 mark and so the camera does not travel to the end of the line.

The only way I have gotten a slower animation is to allow the line to suddenly ascend at the end of the animation to meet the end point. This obviously makes the camera move very quickly at the end.

How can I control how many frames I have and the speed of animation between the start and end points?

If the IPO is a Speed IPO a 45 degree slope will give you a constant speed. A zero degree slope no speed at all and a -45 degree (minus 45 degrees, sloping downwards from left to right) will put the path in reverse.

You need to add Points (CV’s) to your curve. Say you want a constant speed from frame 1 to frame 30, it will slope upward at 45 deg from L to R from frame1 to 30. Then you want it to stop at 30 and stay there till frame 50. Add a Point (Select Curve and Tab into Edit Mode then Ctrl-LMB on the curve at frame 30 and then again at frame 50. Grab the point at 50 and drag it to the same Y height as tat on frame 30. And so on.

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Thank you for your help, but I thought some screen shots might better illustrate exactly what I’m struggling with.

This is what I have after setting a standard path’s IPO curve to linear:
http://img148.imageshack.us/img148/9691/screenshotblenderhomedayi5.png

You can see there’s a line at 230 frames and I’m given a rate of ascent that controls the animation speed.

If I modify that angle to slow the animation down, it can no longer reach the end:
http://img132.imageshack.us/img132/7527/screenshotblenderhomedavc2.png

And if I add another keypoint, the animation can only be the speed I want until the end, where it needs to meet up with the end point:
http://img148.imageshack.us/img148/8019/screenshotblenderhomedawx0.png

That’s what I’m having difficulty with.

How also would I tell where the camera is on any particular frame?

http://uploader.polorix.net//files/111/FlighPathPause.blend

See if that .blend helps at all. Experiment by moving the 3rd Point from the left up and down a touch.

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