"MichaelJF" <mi-### [at] t-onlinede> wrote:
> clipka <ano### [at] anonymousorg> wrote:
> > Am 15.12.2012 20:51, schrieb MichaelJF:
> > > clipka <ano### [at] anonymousorg> wrote:
> > >> Am 12.12.2012 14:56, schrieb gregjohn:
> > >>> Hi. I was starting to experiment with the use of povray to make a single-image
> > >>> sprite sheet.  It would of course be useful to make it using an orthographic
> > >>> camera.  But my figures are getting cut off.   Is there a way around this?
> > >>> TIA.
> > >>
> > >> Move the camera further away, maybe?
> > >
> > > Moving away an orthographic camera? What should be achieved from this?
> >
> > Making the figures not getting cut off.
> >
> > Even in an orthographic render, the cameria position determines what you
> > see: Everything "in front" of the camera is viwithsible, everiything "behind"
> > is not.
>
> With the orthographic camera the up and right vectors determines the visible
> scene and nott
> the distance of the camera  to the desired objects. As far as i experienced.
>
> Best regards,
> michael

Sorry, Clipka was right as ever. I use the orthographic camera only as an
auxilliary tool to view objects which are within or very close to a plane (e.g.
for creating hight_fields) and look perpendicular to this plane, so I didn't
came up with the idea to use the this camera within the middle of a complete
(real) 3d scene. There it cuts of all behind the camera with explains the broken
legs above.

One is influenced by one's habits sometimes too much..

Best regards,
Michael

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James Holsenback <nom### [at] nonecom> wrote:
>
> You guys come up with something and I'll make sure it finds it's way
> into the docs ...

Not sure if it's docworthy or not, but here's one I whipped up in MegaPOV...

The blue rectangle represents the camera (origin, orientation, size) and within
it lies an actual view of the scene. The yellow lines indicate the portion of
the scene the camera is viewing. The red figures march through the orthographic
camera's plane, becoming purple (image 1), or clipped (image 2).

Sam

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Attachments:
Download 'orthocam.png' (135 KB)

Preview of image 'orthocam.png'

"gregjohn" <pte### [at] yahoocom> wrote:
> May I say that this whole thread supports my claim that the camera docs, notably
> the diagram, don't explain what it the orthographic camera does?  I presume
> everyone posting in this thread has in fact RTFM.

I've gone back to the docs on occasion when I'm doing something unusual with the
perspective camera, but I don't recall the last time I did it for the
orthographic camera; it may have been as long ago as February of 2004.

What is clear to me now is that "angle" makes no physical sense with the
orthographic camera, so I never use that keyword.  I just use the right and up
vectors to describe the viewport and be done with it.

I do recall having trouble with the orthographic camera in the misty, distant
past, but whatever the trouble was, my brain didn't see the value in retaining
it.  It may have been foolish attempts to use the sky sphere with this camera;
or it may have been an abortive attempt to make the angle keyword behave before
discovering that the right and up keywords do exactly what I needed done. (Come
to think of it, the sky sphere episodes might be recurring, ending with me
slapping my forehead every time.)

Sam's illustration conveys the camera much better than the existing diagram in
the docs, although Sam's illustration doesn't have a place for the angle.  I
have made no attempt to verify whether the angle keyword in fact does what the
diagram in the docs implies.

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"Cousin Ricky" <rickysttATyahooDOTcom> wrote:
> Sam's illustration conveys the camera much better than the existing diagram in
> the docs, although Sam's illustration doesn't have a place for the angle.

Yes, indeed. But for a documentation or tutorial it needs more explanation (e.g.
meaning of up and right). The problem with writing a doc or tut is, that one has
to know which parameters are used by a special type of camera and which are not.
Angle seems to make no sense, but is it ignored completelly when specified in
the orthographic camera?

Best regards,
Michael

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Le 18/12/2012 08:38, MichaelJF a écrit :
> "Cousin Ricky" <rickysttATyahooDOTcom> wrote:
>> Sam's illustration conveys the camera much better than the existing diagram in
>> the docs, although Sam's illustration doesn't have a place for the angle.
> 
> Yes, indeed. But for a documentation or tutorial it needs more explanation (e.g.
> meaning of up and right). The problem with writing a doc or tut is, that one has
> to know which parameters are used by a special type of camera and which are not.
> Angle seems to make no sense, but is it ignored completelly when specified in
> the orthographic camera?

No, it is not ignored. Thanks to "upward compatibility", when angle is
specified, it change the specification of the orthographic camera to
have a view similar to the one with the perspective camera (it ignore
then the length of the right & up vector to define the area of the image
plane, and recompute them based on angle & direction & the ratio between
up and right... because angle only apply to the width of the picture).

And yet, when angle is not present, the actual lengths of right & up are
very significant, whereas the length of direction is not!

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I think the whole problem is that up and right are best thought of as scalars,
the length in x and y of the image.

Anyway, here's my proposal for a doc/ wiki to explain the orthographic camera.
I'd be delighted if anyone took this and explained it better, made it prettier,
or even explained the regular camera.

In Linux circles, they spoke of a "girlfriend test," whether someone's
non-Linux-enthusiast SO could but up the OS and use it right away. My version of
this for povray is that someone with basic smarts in computers (say a FORTRAN or
BASIC- educated person) could pick up the docs, and on first sitting, make an
image with spheres perfectly in all four corners of the screen.  That I believe
would be a "Holy Grail" goal for the docs.

Four views:  Orthographic up too close, Orthographic sufficiently far away,
"Diagram" of Ortho up too close, "Diagram of Ortho far away.   White plane is
the camera's viewing plane.

#include"transforms.inc"

///-------------------------------------
//  1 means take image with orthographic camera
//  0 means look at scene as a very early draft for diagram
#declare your_orthographicness=1;
///-------------------------------------
///-------------------------------------
//  1 means a view where the camera plane cuts off figures
//  0 means a view where camera plane a healthy distance away
#declare your_too_closedness=0;
///-------------------------------------

#if(your_too_closedness)
        #declare your_location = 3.5*< 0,pow(2,0.5),-pow(2,0.5)> ;
#else
        #declare your_location = 15*<0,pow(2,0.5),-pow(2,0.5)> ;
#end




#declare your_up = 10;
#declare your_right = 10;
#declare your_look_at = 0;
#declare your_look_dirn = your_look_at-your_location;



#if(your_orthographicness)
        camera {orthographic
                location your_location
                look_at your_look_at         up your_up     right your_right
                }


#else
        camera{location <80,80,-25> look_at 0    angle 45}

        box{<-your_right,-your_up,-0.01>,<your_right,your_up,0>
                pigment{rgbt <.9,.9,1,0.5>}
                Reorient_Trans(<0,0,1>,your_look_dirn)
                translate your_location
                }
        sphere   {your_location, 0.5 pigment {rgb 0.1}}
        cylinder {your_location,0.25*(your_look_at-your_location)+your_location,
0.5 pigment {rgb 0.1}}

cone{0.25*(your_look_at-your_location)+your_location,1.5,0.35*(your_look_at-your_location)+your_location,
0  pigment {rgb 0.1}}

#end


sphere {your_look_at,1 pigment {rgb 0.1}}


background {rgb 1}

light_source{<-31010,250000.0,-250000> color rgb 1}
light_source{<12220,500,40000> color rgb 2 shadowless}



//cylinder

sphere{<-10,0,-10*pow(2,0.5)>,3.2 pigment {green 1}}
sphere{< 10,0,-10*pow(2,0.5)>,3.2 pigment {green 1}}
sphere{<-10,0, 10*pow(2,0.5)>,3.2 pigment {green 1}}
sphere{< 10,0, 10*pow(2,0.5)>,3.2 pigment {green 1}}

cylinder{<-10,0,-10*pow(2,0.5)>,<-10,0,-10*pow(2,0.5)>+100*<
0.00,10*pow(2,0.5),-10*pow(2,0.5)> ,.2 pigment {green 1}}
cylinder{< 10,0,-10*pow(2,0.5)>,< 10,0,-10*pow(2,0.5)>+100*<
0.00,10*pow(2,0.5),-10*pow(2,0.5)> ,.2 pigment {green 1}}
cylinder{<-10,0, 10*pow(2,0.5)>,<-10,0, 10*pow(2,0.5)>+100*<
0.00,10*pow(2,0.5),-10*pow(2,0.5)> ,.2 pigment {green 1}}
cylinder{< 10,0, 10*pow(2,0.5)>,< 10,0, 10*pow(2,0.5)>+100*<
0.00,10*pow(2,0.5),-10*pow(2,0.5)> ,.2 pigment {green 1}}

cylinder{0,100*< 0.00,10*pow(2,0.5),-10*pow(2,0.5)> ,.2 pigment {green 1}}





#declare nx=0;
#while(nx<16)
        #declare nz=0;
        #while(nz<16)

        sphere{0,1. pigment {red 1} translate <(nx-6.5)*2,0,(nz-6.5)*2> rotate
30*y}

        #declare nz=nz+1;
        #end
#declare nx=nx+1;
#end

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Attachments:
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"MichaelJF" <mi-### [at] t-onlinede> wrote:
> "Cousin Ricky" <rickysttATyahooDOTcom> wrote:
> > Sam's illustration conveys the camera much better than the existing diagram in
> > the docs, although Sam's illustration doesn't have a place for the angle.
>
> Yes, indeed. But for a documentation or tutorial it needs more explanation (e.g.
> meaning of up and right).

Oookay.... I thought you guys just wanted a portrayal of the problem, not a
complete camera diagram :P For such, I would've adhered to the documentation's
style. Perhaps sometime later I'll throw something together in Illustrator.

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