John VanSickle <evi### [at] KOSHERhotmailcom> wrote:

>
> I do however note that the moon is rotating much faster than any
> spherical body will in real life.  The earth, for instance, rotates one
> degree every four minutes.

Just a fanciful depiction, to give a bit more life to the scene. But it makes me
wonder if there are physical laws preventing such a body (Earth's moon, for
example) from rotating that fast. Would it fly apart?

Neutron stars are known to rotate extremely rapidly. But then again, they are
extremely dense, with tremendous gravitational forces holding them together.

Off topic: It would be interesting to know what a neutron star 'looks like' if
we could actually see one CU through a telescope. Since it's only neutrons (no
full atoms with electrons), and since light is an electromagnetic phenomenon,
what happens when a photon impinges on it? Light needs electrons to 'react' with
when it hits an object, AFAIU. An interesting 'thought experiment.'

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John VanSickle <evi### [at] KOSHERhotmailcom> wrote:

>
> ...the 180 degree blurring has
> one benefit:  You only have to render half as many frames to achieve the
> same level of blurring.
>

Yes indeed. My animation code block is set up to do that as well; but for this
animation I originally rendered *all* the motion, as I didn't think of posting a
'180-deg version' until later. Then it was just a simple matter of skipping
frames during the averaged re-rendering. BTW, the re-rendering process goes
*fast*, as it can be run at POV-Ray's lowest-quality setting. Just images
projected on the front of a box, with ambient 1.0.  Not very *elegant*, but
extremely useful.

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Alain <kua### [at] videotronca> wrote:

>
> That's how they did all realistic space explosions, those where you
> don't see smoke going up and debrits going down...
> Some samples:
> The original Star war trilogy.
> The original StarTreck.
> The original Battlestar Galactica.

When I was a kid, I made lots of 8mm home movies--nutty science-fiction stuff
and animation--and the funny thing is, this technique never occurred to me at
the time! Yet it's so simple.

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John VanSickle <evi### [at] KOSHERhotmailcom> wrote:

>
> Actually you can get away without collision detection on a fly-through
> like this by simply having each asteroid stay in place, and have the
> camera take a more winding route.  The spinning of the asteroids and the
> motion of the camera will help hide the cheating.

I think I may have used the phrase 'collision detection' by mistake. The
meteoroids in my scene actually *are* static, BTW (except for rotations); the
camera just flies through 'em. What I meant earlier was that I was trying to
find a method to keep them from simply 'overlapping.' But I forgot the correct
term for that. :-[  Uh, obviously, I still can't remember it...

I actually did run a different kind of test animation, just for fun, with the
meteors all zipping through space in random directions. The result was total
chaos! The camera's point of view couldn't really lock onto anything, no real
reference. (You would think that the moon and the background would have served
that purpose; but all those flying objects made the scene way too disorienting.)

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> John VanSickle <evi### [at] KOSHERhotmailcom> wrote:
>
>>
>> I do however note that the moon is rotating much faster than any
>> spherical body will in real life.  The earth, for instance, rotates one
>> degree every four minutes.
>
> Just a fanciful depiction, to give a bit more life to the scene. But it makes me
> wonder if there are physical laws preventing such a body (Earth's moon, for
> example) from rotating that fast. Would it fly apart?
>
> Neutron stars are known to rotate extremely rapidly. But then again, they are
> extremely dense, with tremendous gravitational forces holding them together.
>
> Off topic: It would be interesting to know what a neutron star 'looks like' if
> we could actually see one CU through a telescope. Since it's only neutrons (no
> full atoms with electrons), and since light is an electromagnetic phenomenon,
> what happens when a photon impinges on it? Light needs electrons to 'react' with
> when it hits an object, AFAIU. An interesting 'thought experiment.'
>
>
>

If a body spin to fast, it won't be able to condense into a planet or 
moon. There is a point where it can, theoreticaly, form into an almost 
pancake shape...
If it get accelerated, by some obscure mean, it can fly apart.

For the neutron star, you'll see the incandecent gaz cloud that could be 
called it's athmosphere, or have degenerated into a solid crust but 
still stay "normal" matter.
If you where to remove that outer layer to reveal the all neutron core, 
well, it may be perfectly transparent, only detectable by the 
gravitational bending of light... There is also the possibility that 
there is not enough place for the photons to squeeze through. What appen 
when a photon hit a neutron square on? There could be some reflection...



Alain

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Alain <kua### [at] videotronca> wrote:

>
> If a body spin to fast, it won't be able to condense into a planet or
> moon. There is a point where it can, theoreticaly, form into an almost
> pancake shape...


Ah, I didn't think of that: At such a fast rotation rate, there would have been
no Moon to begin with! (The only thing I can think of that would cause a Moon to
spin faster *once it was formed* would be, say, a near-miss from some other,
bigger object, with a much larger gravitational field. But that would have torn
the Moon apart again, probably.)
>
> For the neutron star, you'll see the incandecent gaz cloud that could be
> called it's athmosphere, or have degenerated into a solid crust but
> still stay "normal" matter.
> If you where to remove that outer layer...

Ah, right again. The neutron star, with its huge gravitational and magnetic
fields, would obviously attract all the other loose matter in it's
vicinity--forming a crust. So it may never be possible to see a 'naked' neutron
star. And the photon question becomes merely a hypothetical one.

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On 1/27/2013 10:29 PM, Kenneth wrote:
> John VanSickle <evi### [at] KOSHERhotmailcom> wrote:
>
>>
>> ...the 180 degree blurring has
>> one benefit:  You only have to render half as many frames to achieve the
>> same level of blurring.
>>
>
> Yes indeed. My animation code block is set up to do that as well; but for this
> animation I originally rendered *all* the motion, as I didn't think of posting a
> '180-deg version' until later. Then it was just a simple matter of skipping
> frames during the averaged re-rendering. BTW, the re-rendering process goes
> *fast*, as it can be run at POV-Ray's lowest-quality setting. Just images
> projected on the front of a box, with ambient 1.0.  Not very *elegant*, but
> extremely useful.

POV-Ray is a rather flexible post-processing tool.  I've done fades, 
wipes, masking, and titling.

For instance, in a few of my IRTC animations I have a warp gate open up 
in space, revealing the yes-it-was-stolen-from-Babylon-5 hyperspace, and 
then ships use the gate to transit from one space to the other.  I have 
one rendering of the ship and the gate in normal space, another 
rendering of the ship and the gate in hyperspace, another rendering that 
is just a mask, and then a final rendering to transition from the normal 
space view where the mask is black to the hyperspace view where the mask 
is totally white.

You can see the two animations where I do this here:

http://www.irtc.org/anims/2004-10-15.html
http://tc-rtc.co.uk/imagenewdisplay/animation/index92.html

Regards,
John

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John VanSickle <evi### [at] KOSHERhotmailcom> wrote:

>
> You can see the two animations where I do this here:
>
> http://www.irtc.org/anims/2004-10-15.html

Is this one supposed to be so short? The file is only a couple of seconds long;
looks like it has been truncated.

> http://tc-rtc.co.uk/imagenewdisplay/animation/index92.html

Very cool. Some nice effects there; the wormhole/hyperspace thing is really
good. And I do like your acceleration/deceleration of the camera pan. My own way
of doing that is kind of cumbersome (and not wholly effective.) For the
acceleration, something like

#if(clock >= .2)
and using
pow(ceil(..multiplier.. *(clock - .2),0,1),2)  (...I *think* this is right...)

but also having to figure out what this block should be to smoothly reverse the
process, for the deceleration. The pow(...) thing is needed for the smoothness
of course, but it also makes it difficult to figure out the right value to use.
Do you have a more elegant and controllable means to do this, that you simply
plug in whenever it's needed?  Maybe one that I could steal?  ;-)

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> John VanSickle <evi### [at] KOSHERhotmailcom> wrote:
>
>>
>> You can see the two animations where I do this here:
>>
>> http://www.irtc.org/anims/2004-10-15.html
>
> Is this one supposed to be so short? The file is only a couple of seconds long;
> looks like it has been truncated.
>
>> http://tc-rtc.co.uk/imagenewdisplay/animation/index92.html
>
> Very cool. Some nice effects there; the wormhole/hyperspace thing is really
> good. And I do like your acceleration/deceleration of the camera pan. My own way
> of doing that is kind of cumbersome (and not wholly effective.) For the
> acceleration, something like
>
> #if(clock >= .2)
> and using
> pow(ceil(..multiplier.. *(clock - .2),0,1),2)  (...I *think* this is right...)
>
> but also having to figure out what this block should be to smoothly reverse the
> process, for the deceleration. The pow(...) thing is needed for the smoothness
> of course, but it also makes it difficult to figure out the right value to use.
> Do you have a more elegant and controllable means to do this, that you simply
> plug in whenever it's needed?  Maybe one that I could steal?  ;-)
>

Why don't you use a spline to move the camera. You set the control 
points according to where you want the camera to be at a given time. If 
the control points are far apart, the amera move fast, if they are close 
toggeder, the movment is slow, and if there are coincident points, the 
camera stops.

You can use a second spline for the look_at point, with possibly a 
control for the zooming or banking...
A direction length or angle can be included as a fourth vector component.


Alain

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Alain <kua### [at] videotronca> wrote:

>
> Why don't you use a spline to move the camera. You set the control
> points according to where you want the camera to be at a given time. If
> the control points are far apart, the amera move fast, if they are close
> toggeder, the movment is slow, and if there are coincident points, the
> camera stops.
>

Yes, a spline is useful for doing as you say, and produces nice smooth movement.
In most of my own animations, though, I use clock values (or frame numbers) with
some math.  Just a personal preference, I guess. It seems easier to control, in
a more precise way. With a spline (an easy-to-use natural spline, for example)
if you change or move a control point, it causes the curve there to change in a
not-so-intuitive way (based on the control points to either 'side' of it.) Which
may or may not produce the exact effect you're trying to get. Using just clock
values instead, I can start a camera movement precisely where I want in the
animation, without wondering if the movement is actually going to start several
frames behind or ahead (as might be the case with a smooth spline.)

However, I do imagine that adding several identical spline points close together
could probably solve that--'breaking' the curve there, or uncoupling it from the
previous control point. It's not as 'intuitive' as I would like, but I'll give
it a try.

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