I'm having (again) a little trouble wrapping my mind around a specific homemade
probelm.
I'm animating a camera along a complicated path with hundreds of nodes. My nodes
are hand generated and therefore have not equal distances to each other. This is
why I use a spreadsheet program to generate time indexes dependent on the
distance between nodes in order to smoothen the overall speed. I wrote a
unix(awk) script that converts my csv file to a povray natural spline.
Everything works well. I can fine-tune my path by changing the coordinates in
the spreadsheet and then quickly convert the new spline to povray using my
script.

Now I would like to alter the speed of my traveling camera while it is on the
way. This is where my trouble starts. I want my camera to slow down in certain
places and then speed up again.I know how to use Chris's ClockMod for camera
animation with smooth start and stop at the very beginning and end of the
complete spline (using S-Curve) but I don't want to tear my animation path
apart.

Does anybody have any idea how I could use C. Colefax's clockmod in a way that I
can choose between what time indexes a S-Curve will be applied several times in
succession? I tried clock_start and clock_finish but with no success.

THANX!
Andi

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CAD-Andi wrote:

> Now I would like to alter the speed of my traveling camera while it is on the
> way.

I don't know about the ClockMod macro, but given your process,
wouldn't it be easiest to specify the desired speed at each node
in your spreadsheet and interpolate that in your script too (so,
instead of generating an equidistant distribution, make the
distances larger where the speed is higher)?

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I think I have the solution. I simply add the product of mclock with the
difference of start and end clock to the current clock and specify a camera per
section using this altered clock value. It Works for me!

#declare take1_clock = take1_start+((take1_end-take1_start)*mclock);

Thanks for considering though ...
:-)

Andi

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Thanks Christian for your input.
Unfortunately that is exactly what I would like to avoid. The path is very
complicated with a lot of objects in the way that I have to navigate around. At
the same time I'm controlling the camera heading with a separate spline. It
would be extremely cumbersome if not impossible within the given timeframe to
program the path and adjust the distances between the nodes so that speed is
smoothly controlled. Luckily I found the solution already (See post below).
Thanks for your answer though! This is what makes Povray great, active users
that are willing to help each other! Way to go!

Andi

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> I'm having (again) a little trouble wrapping my mind around a specific homemade
> probelm.
> I'm animating a camera along a complicated path with hundreds of nodes. My nodes
> are hand generated and therefore have not equal distances to each other. This is
> why I use a spreadsheet program to generate time indexes dependent on the
> distance between nodes in order to smoothen the overall speed. I wrote a
> unix(awk) script that converts my csv file to a povray natural spline.
> Everything works well. I can fine-tune my path by changing the coordinates in
> the spreadsheet and then quickly convert the new spline to povray using my
> script.
>
> Now I would like to alter the speed of my traveling camera while it is on the
> way. This is where my trouble starts. I want my camera to slow down in certain
> places and then speed up again.I know how to use Chris's ClockMod for camera
> animation with smooth start and stop at the very beginning and end of the
> complete spline (using S-Curve) but I don't want to tear my animation path
> apart.
>
> Does anybody have any idea how I could use C. Colefax's clockmod in a way that I
> can choose between what time indexes a S-Curve will be applied several times in
> succession? I tried clock_start and clock_finish but with no success.
>
> THANX!
> Andi
>
>

You have a spline for the location of the camera and another for it's 
look_at point. Why not another for it's speed?

You follow that last one linearly, and you get the instantaneous speed 
of the camera. It can also include the speed of the look_at point and, 
if you want, the angle of view so that you can have the camera smoothly 
zoom in and out at specific moments.



Alain

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Alain <aze### [at] qwertyorg> wrote:
>
> You have a spline for the location of the camera and another for it's
> look_at point. Why not another for it's speed?
>
> You follow that last one linearly, and you get the instantaneous speed
> of the camera. It can also include the speed of the look_at point and,
> if you want, the angle of view so that you can have the camera smoothly
> zoom in and out at specific moments.
>
>
>
> Alain

Thanks Alain for your input Alain. Great idea! Maybe I'll try to figure out how
to do this during my next project. For now I finished this one with my rather
un-elegant solution applying "clock mod" over parts of the animation.

Check out the final product on youtube:
http://www.youtube.com/watch?v=prUzhi9mER4&hd=1

Thanks again!
Andi

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