hello,

i have a question but i'm not exactly sure of the terminology.  i've
got a scene looking out a window to a sky plane.  i've carpetted a
lot of the ground, the x/z plane, with gilles's grass, but i want the
horizon line higher than what it is.  isn't the horizon line something
similar to a vanishing point in a perspective drawing?  can't it be
adjusted up or down without tilting or repositioning the camera?
maybe not.

i looked in the pov docs under sky, plane, horizon, and vanishing,
but i didn't have any luck.

thank you, miker

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On Mon, 12 Nov 2001 12:42:34 -0500, MR wrote:
> hello,
> 
> i have a question but i'm not exactly sure of the terminology.  i've
> got a scene looking out a window to a sky plane.  i've carpetted a
> lot of the ground, the x/z plane, with gilles's grass, but i want the
> horizon line higher than what it is.  isn't the horizon line something
> similar to a vanishing point in a perspective drawing?  can't it be
> adjusted up or down without tilting or repositioning the camera?

Sure.  You can move the plane up, which is pretty much the same thing
as moving the camera down.  

-- 
#macro R(L P)sphere{L F}cylinder{L P F}#end#macro P(V)merge{R(z+a z)R(-z a-z)R(a
-z-z-z a+z)torus{1F clipped_by{plane{a 0}}}translate V}#end#macro Z(a F T)merge{
P(z+a)P(z-a)R(-z-z-x a)pigment{rgbf 1}hollow interior{media{emission 3-T}}}#end 
Z(-x-x.2x)camera{location z*-10rotate x*90normal{bumps.02scale.05}}

Post a reply to this message

hahaha.  ok.  thanks ron.  that wasn't exactly what i had in
mind but i think it comes close to answering my question.
i wished for the plane to stay right where it was on the x/z
plane... i just wanted the line where it vanished into the
horizon to be higher, without juggling the camera.  i am
going to assume now that the horizon line can only be
adjusted by either adjusting the camera or the plane.

thanks, miker


"Ron Parker" <ron### [at] povrayorg> wrote in message
news:slr### [at] fwicom...
> On Mon, 12 Nov 2001 12:42:34 -0500, MR wrote:
> > hello,
> >
> > i have a question but i'm not exactly sure of the terminology.  i've
> > got a scene looking out a window to a sky plane.  i've carpetted a
> > lot of the ground, the x/z plane, with gilles's grass, but i want the
> > horizon line higher than what it is.  isn't the horizon line something
> > similar to a vanishing point in a perspective drawing?  can't it be
> > adjusted up or down without tilting or repositioning the camera?
>
> Sure.  You can move the plane up, which is pretty much the same thing
> as moving the camera down.
>
> --
> #macro R(L P)sphere{L F}cylinder{L P F}#end#macro P(V)merge{R(z+a z)R(-z
a-z)R(a
> -z-z-z a+z)torus{1F clipped_by{plane{a 0}}}translate V}#end#macro Z(a F
T)merge{
> P(z+a)P(z-a)R(-z-z-x a)pigment{rgbf 1}hollow interior{media{emission
3-T}}}#end
> Z(-x-x.2x)camera{location z*-10rotate x*90normal{bumps.02scale.05}}

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Your job is now that of the photographer: You've got a world and a camera. Try
to find the best shot. Unlike your average photographer however, if that tree is
in your way you 'can' move it. :)

Batronyx ^"^

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not just the photographer, bat... i'm god now.  i'm not just
taking pictures... i CREATED the world.  and i'll tell you, the
difficulty of the job has given me a lot more respect for the
man upstairs.  ;-)

miker


"Batronyx" <bat### [at] alliancecablenet> wrote in message
news:3bf0ab20$1@news.povray.org...
> Your job is now that of the photographer: You've got a world and a camera.
Try
> to find the best shot. Unlike your average photographer however, if that
tree is
> in your way you 'can' move it. :)
>
> Batronyx ^"^
>
>

Post a reply to this message

"MR" <a### [at] bnet> wrote in message news:3bf171a0@news.povray.org...
> not just the photographer, bat... i'm god now.  i'm not just
> taking pictures... i CREATED the world.  and i'll tell you, the
> difficulty of the job has given me a lot more respect for the
> man upstairs.  ;-)
>

AMEN!

Post a reply to this message

"MR" <a### [at] bnet> wrote in message news:3bf00a23$1@news.povray.org...
> hello,
>
> i have a question but i'm not exactly sure of the terminology.  i've
> got a scene looking out a window to a sky plane.  i've carpetted a
> lot of the ground, the x/z plane, with gilles's grass, but i want the
> horizon line higher than what it is.  isn't the horizon line something
> similar to a vanishing point in a perspective drawing?  can't it be
> adjusted up or down without tilting or repositioning the camera?
> maybe not.

Widen the field of view of the camera (lower direction or higher angle or
change right & up) and crop the image in a drawing software. If you are sure
you won't reconsider the left-right borders, you can change only the up
vector and the +h output option. To gain some more speed (if the render is
slow) do not render the added image part on top (partial image rendering
with +sr).

For example :
if your camera is the default 4/3 one and you currently render in 800*600 ;
if you want to raise the horizon by 150 pixels :
To raise the horizon by 150 pixels, you need to render 150 more pixels in
the bottom of the image. As the horizon won't really move, it means you will
also need to add 150 pixels in the top of the image. In other words, you
have to extend the image symetrically. So the total height of the image has
to gain 2*150 pixels = 300 pixels.

+h900 ;instead of +h600

Now you have to change your pov code (if you render with just the +h change
all you will get is a stretched image). You have to tell pov you want to see
more in the vertical direction :

up 1/600*900*y // instead of the default 1*y


I know it isn't very clear... I hope it helps,
If it doesn't, questions will help me to explain ;-)


Povingly,

Philippe

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Knew I was forgoting something in the example :

You do not want to render the 150 lines you added in the top of the images,
so you add in the options :

+sr150

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New solution : see my "Sheared camera" post in p.b.i


Povingly,


Philippe

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Vanishing points come from 3D geometry:

If you cast a ray from the camera in a given direction, it will cross your
screen in one point V.

That means that the line that sart at the camera location and that pass at
this point is seen as a unique point : V.

Any other parallel line D will draw a segment on the screen, but as you are
considering farther points belonging to D, the image of these points is
getting closer to point V: the distance from D to the first line is
constant, and this distance look smaller and smaller when tyou are looking
farther and farther.

So, if you want to control the vanishing point of an horizontal plane, it is
worthless to move the camera up and down, this will affect only the
foreground. You must control the look_at parameter, or rotate the plane.

Chaps.


"Batronyx" <bat### [at] alliancecablenet> wrote in message
news:3bf1f0b8@news.povray.org...
>
> "MR" <a### [at] bnet> wrote in message news:3bf171a0@news.povray.org...
> > not just the photographer, bat... i'm god now.  i'm not just
> > taking pictures... i CREATED the world.  and i'll tell you, the
> > difficulty of the job has given me a lot more respect for the
> > man upstairs.  ;-)
> >
>
> AMEN!
>
>

Post a reply to this message