Understanding x, y, z, zoom, and focus interaction.

[Gregory Sogorka]

I am trying to wrap my head around the relevance and interaction of
these values.  So it seems to me there are a number of values
affecting a Camera3D object which when insulated I think I understand.
 But when these values begin to interact with dimension passed to
constructors such as cubes my understanding becomes a bit hazy.



Let me be a bit more descriptive:

1. I have a cube that I am creating with constant dimensions 100x100x100

:::: new Cube ( _ml, 100, 100, 100 )

2. I have read through the classes for the Camera3D object and think I
understand the differences between zoom and focus. As the class
states, the zoom is the scale at which the 3D objects are rendered;
and the focus is the closest a camera can be to any object.


Now I have run some tests and rendered the cube and measured it
dimensions with a pixel ruler tool from Art Directors Toolkit.

constants throughout my experiment were:

camera3d.x = 0;
camera3d.y = 0;
camera3d.zoom = 2; ( as set by the constructor )
camera3d.focus = 100; ( as set by the constructor );






with those constant values I altered the z value of the camera3d
object and measured the width of the resulting cube:

z = 50 width = 200;
z = 75 width = 165;
z= 100 width = 142;
z = 125 width = 125;
z = 150 width = 112;
z = 175 width = 100;


So my question is  why does the z of 175 result in the actual pixel
width sent to the cube constructor being rendered on teh screen.  I am
looking for some sort of pattern in the changes but  cant seem to
grasp it. Could anyone help me out with some illumination to this
simple concept and the broader picture of how all these values
interact with one another ? or point me to a tutorial that maps these
things out clearly.


All the best.
G

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[o renken]

hm... focus is the focal length of the camera-lens. think about an objective for a normal camera. around 28 youve got a fisheye-lens. around 155 youve got a tele-objective (its the german name for it, i dont know in english) . as smaller the angle, as wider the field-of-view, the visible area you will se throught your lens. as smaller the angle, as more perspective.
use more than one cube and try
focus=100
focus=5000 or more (gets close to isometric displaying)

and the zoom makes the things look bigger. think again at the ordinary digital-camera. the most of them has zoom.

maybe this may help you a little bit... ?

olee

2007/11/2, Gregory Sogorka <blackberryoctopus@...>:

I am trying to wrap my head around the relevance and interaction of
these values.  So it seems to me there are a number of values
affecting a Camera3D object which when insulated I think I understand.
But when these values begin to interact with dimension passed to
constructors such as cubes my understanding becomes a bit hazy.



Let me be a bit more descriptive:

1. I have a cube that I am creating with constant dimensions 100x100x100

:::: new Cube ( _ml, 100, 100, 100 )

2. I have read through the classes for the Camera3D object and think I
understand the differences between zoom and focus. As the class
states, the zoom is the scale at which the 3D objects are rendered;
and the focus is the closest a camera can be to any object.


Now I have run some tests and rendered the cube and measured it
dimensions with a pixel ruler tool from Art Directors Toolkit.

constants throughout my experiment were:

camera3d.x = 0;
camera3d.y = 0;
camera3d.zoom = 2; ( as set by the constructor )
camera3d.focus = 100; ( as set by the constructor );






with those constant values I altered the z value of the camera3d
object and measured the width of the resulting cube:

z = 50 width = 200;
z = 75 width = 165;
z= 100 width = 142;
z = 125 width = 125;
z = 150 width = 112;
z = 175 width = 100;


So my question is  why does the z of 175 result in the actual pixel
width sent to the cube constructor being rendered on teh screen.  I am
looking for some sort of pattern in the changes but  cant seem to
grasp it. Could anyone help me out with some illumination to this
simple concept and the broader picture of how all these values
interact with one another ? or point me to a tutorial that maps these
things out clearly.


All the best.
G

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[Gregory Sogorka]

If this is the fact, I am interested to know what unit is used to
measure focal length.  For instance, you state that a focus value of
28 is a fisheye lens when is terms of miillimeters a 10-15mm lens is a
fisheye lens.  How do mm values of real lens translate in the
papervision world ?

G

On 11/3/07, o renken <renkster@...> wrote:

> hm... focus is the focal length of the camera-lens. think about an objective
> for a normal camera. around 28 youve got a fisheye-lens. around 155 youve
> got a tele-objective (its the german name for it, i dont know in english) .
> as smaller the angle, as wider the field-of-view, the visible area you will
> se throught your lens. as smaller the angle, as more perspective.
> use more than one cube and try
> focus=100
> focus=5000 or more (gets close to isometric displaying)
>
> and the zoom makes the things look bigger. think again at the ordinary
> digital-camera. the most of them has zoom.
>
> maybe this may help you a little bit... ?
>
> olee
>
> 2007/11/2, Gregory Sogorka <blackberryoctopus@...>:
> >
> > I am trying to wrap my head around the relevance and interaction of
> > these values.  So it seems to me there are a number of values
> > affecting a Camera3D object which when insulated I think I understand.
> > But when these values begin to interact with dimension passed to
> > constructors such as cubes my understanding becomes a bit hazy.
> >
> >
> >
> > Let me be a bit more descriptive:
> >
> > 1. I have a cube that I am creating with constant dimensions 100x100x100
> >
> > :::: new Cube ( _ml, 100, 100, 100 )
> >
> > 2. I have read through the classes for the Camera3D object and think I
> > understand the differences between zoom and focus. As the class
> > states, the zoom is the scale at which the 3D objects are rendered;
> > and the focus is the closest a camera can be to any object.
> >
> >
> > Now I have run some tests and rendered the cube and measured it
> > dimensions with a pixel ruler tool from Art Directors Toolkit.
> >
> > constants throughout my experiment were:
> >
> > camera3d.x = 0;
> > camera3d.y = 0;
> > camera3d.zoom = 2; ( as set by the constructor )
> > camera3d.focus = 100; ( as set by the constructor );
> >
> >
> >
> >
> >
> >
> > with those constant values I altered the z value of the camera3d
> > object and measured the width of the resulting cube:
> >
> > z = 50 width = 200;
> > z = 75 width = 165;
> > z= 100 width = 142;
> > z = 125 width = 125;
> > z = 150 width = 112;
> > z = 175 width = 100;
> >
> >
> > So my question is  why does the z of 175 result in the actual pixel
> > width sent to the cube constructor being rendered on teh screen.  I am
> > looking for some sort of pattern in the changes but  cant seem to
> > grasp it. Could anyone help me out with some illumination to this
> > simple concept and the broader picture of how all these values
> > interact with one another ? or point me to a tutorial that maps these
> > things out clearly.
> >
> >
> > All the best.
> > G
> >
> > _______________________________________________
> > Papervision3D mailing list
> > Papervision3D@...
> >
> http://osflash.org/mailman/listinfo/papervision3d_osflash.org
> >
>
>
>
> --
>  http://www.renkster.de/#/about/
> _______________________________________________
> Papervision3D mailing list
> Papervision3D@...
> http://osflash.org/mailman/listinfo/papervision3d_osflash.org
>
>

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[Jon Bradley-2]

On Nov 3, 2007, at 2:39 PM, Gregory Sogorka wrote:

If this is the fact, I am interested to know what unit is used to

measure focal length.

The metric system. Of course, that can also depend on who you talk to. I'm a stickler about optics terms (at least, that's what I went to school for - physics/optical engineering).

It's measured in meters, but often printed in mm because it's easier to read than say, .0XX. 

For instance, you state that a focus value of

28 is a fisheye lens when is terms of miillimeters a 10-15mm lens is a

fisheye lens.

A fisheye lens is a wide angle lens. There are two types. Circular and Full-Frame .

Circular fisheye lenses usually the focal length is somewhere between 8-10mm. For a full-frame it's around 15-16mm.

A 28mm lens is not a 'fisheye' lens. It's just a normal wide angle lens.

How do mm values of real lens translate in the

papervision world ?

Oof. Who knows. :)

- jon

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[Noah Aronsson-Brown]

from a video tutorial that John Grden (one of the core PV3D developers) did, i found out this magical nugget of info: using the default focal length of 100, and setting the zoom value to 11 will result in a one to one ratio of display object size to displayed object size.

It helped me, hope it helps you too!

.n

Gregory Sogorka wrote:

I am trying to wrap my head around the relevance and interaction of
these values.  So it seems to me there are a number of values
affecting a Camera3D object which when insulated I think I understand.
 But when these values begin to interact with dimension passed to
constructors such as cubes my understanding becomes a bit hazy.



Let me be a bit more descriptive:

1. I have a cube that I am creating with constant dimensions 100x100x100

:::: new Cube ( _ml, 100, 100, 100 )

2. I have read through the classes for the Camera3D object and think I
understand the differences between zoom and focus. As the class
states, the zoom is the scale at which the 3D objects are rendered;
and the focus is the closest a camera can be to any object.


Now I have run some tests and rendered the cube and measured it
dimensions with a pixel ruler tool from Art Directors Toolkit.

constants throughout my experiment were:

camera3d.x = 0;
camera3d.y = 0;
camera3d.zoom = 2; ( as set by the constructor )
camera3d.focus = 100; ( as set by the constructor );






with those constant values I altered the z value of the camera3d
object and measured the width of the resulting cube:

z = 50 width = 200;
z = 75 width = 165;
z= 100 width = 142;
z = 125 width = 125;
z = 150 width = 112;
z = 175 width = 100;


So my question is  why does the z of 175 result in the actual pixel
width sent to the cube constructor being rendered on teh screen.  I am
looking for some sort of pattern in the changes but  cant seem to
grasp it. Could anyone help me out with some illumination to this
simple concept and the broader picture of how all these values
interact with one another ? or point me to a tutorial that maps these
things out clearly.


All the best.
G

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