parallel projection 
Author Message
 parallel projection

Hi group,

As I understand, the orthographic camera that was present in vrml 1.0
was removed in vrml 2.0 / vrml 97. For my project I have to do
parallel projections... is there a way to achieve this?

Thanks,

Mark.



Mon, 22 Aug 2005 06:31:44 GMT  
 parallel projection

Quote:

> Hi group,

> As I understand, the orthographic camera that was present in vrml 1.0
> was removed in vrml 2.0 / vrml 97. For my project I have to do
> parallel projections... is there a way to achieve this?

Have you tried setting the fieldOfView of a Viewpoint to a very small
value? This is approximately parallel projection. The world then looks
like if viewed through a telescope. You should set the position of
the Viewpoint to be far away from the object, otherwise the small
fieldOfView makes you see only a very small spot of the object.

try the following file.

Herbert

#VRML V2.0 utf8

NavigationInfo
{
     type ["EXAMINE" "ANY"]

Quote:
}

Transform
{
     translation -3 0 0

     children Shape
     {
         appearance Appearance {
             material Material {
                 diffuseColor .02 .24 .53
                 specularColor .32 .4 .4
                 emissiveColor .01 .12 .27
                 ambientIntensity .0333
                 shininess .54
             }
         }

         geometry Sphere
         {

         }
     }

Quote:
}

Transform
{
     translation 3 0 0

     children Shape
     {
         appearance Appearance {
             material Material {
                 diffuseColor .24 .53 .02
                 specularColor .4 .4 .32
                 emissiveColor .12 .27 .01
                 ambientIntensity .0333
                 shininess .54
             }
         }

         geometry Sphere
         {
         }
     }

Quote:
}

Viewpoint
{
     fieldOfView .1
     position 0 0 100

     description "parallel"

Quote:
}

Viewpoint
{
     description "normal"

Quote:
}

# end of file.


Tue, 06 Sep 2005 06:29:36 GMT  
 parallel projection

Quote:

> Hi group,

> As I understand, the orthographic camera that was present in vrml 1.0
> was removed in vrml 2.0 / vrml 97. For my project I have to do
> parallel projections... is there a way to achieve this?

Have you tried setting the fieldOfView of a Viewpoint to a very small
value? This is approximately parallel projection. The world then looks
like if viewed through a telescope. You should set the position of
the Viewpoint to be far away from the object, otherwise the small
fieldOfView makes you see only a very small spot of the object.

try the following file.

Herbert

#VRML V2.0 utf8

NavigationInfo
{
     type ["EXAMINE" "ANY"]

Quote:
}

Transform
{
     translation -3 0 0

     children Shape
     {
         appearance Appearance {
             material Material {
                 diffuseColor .02 .24 .53
                 specularColor .32 .4 .4
                 emissiveColor .01 .12 .27
                 ambientIntensity .0333
                 shininess .54
             }
         }

         geometry Sphere
         {

         }
     }

Quote:
}

Transform
{
     translation 3 0 0

     children Shape
     {
         appearance Appearance {
             material Material {
                 diffuseColor .24 .53 .02
                 specularColor .4 .4 .32
                 emissiveColor .12 .27 .01
                 ambientIntensity .0333
                 shininess .54
             }
         }

         geometry Sphere
         {
         }
     }

Quote:
}

Viewpoint
{
     fieldOfView .1
     position 0 0 100

     description "parallel"

Quote:
}

Viewpoint
{
     description "normal"

Quote:
}

# end of file.


Tue, 06 Sep 2005 06:32:30 GMT  
 parallel projection
Hi Herbert,

Thanks for your answer. After I posed my question I searched the
archives of this group (should have done that before, I guess). This
question has been asked before and all the answers are the same as
yours, except for one, which I didn't understand... I'll try and find
that post again.
So setting the field of view to a small value seems to be the only way
to achieve my goal. But it only approximates parallel projection, in
some cases this is not good enough. And setting the FOV to a very
small value (say 0.001) seems to induce rendering problems (flickering
polygons). Well hopefully in the next version of VRML the orthographic
camera will return.

Mark.

On Thu, 20 Mar 2003 23:32:30 +0100, Herbert Stocker

Quote:


>> Hi group,

>> As I understand, the orthographic camera that was present in vrml 1.0
>> was removed in vrml 2.0 / vrml 97. For my project I have to do
>> parallel projections... is there a way to achieve this?

>Have you tried setting the fieldOfView of a Viewpoint to a very small
>value? This is approximately parallel projection. The world then looks
>like if viewed through a telescope. You should set the position of
>the Viewpoint to be far away from the object, otherwise the small
>fieldOfView makes you see only a very small spot of the object.

>try the following file.

>Herbert

>#VRML V2.0 utf8

>NavigationInfo
>{
>     type ["EXAMINE" "ANY"]
>}

>Transform
>{
>     translation -3 0 0

>     children Shape
>     {
>         appearance Appearance {
>             material Material {
>                 diffuseColor .02 .24 .53
>                 specularColor .32 .4 .4
>                 emissiveColor .01 .12 .27
>                 ambientIntensity .0333
>                 shininess .54
>             }
>         }

>         geometry Sphere
>         {

>         }
>     }
>}

>Transform
>{
>     translation 3 0 0

>     children Shape
>     {
>         appearance Appearance {
>             material Material {
>                 diffuseColor .24 .53 .02
>                 specularColor .4 .4 .32
>                 emissiveColor .12 .27 .01
>                 ambientIntensity .0333
>                 shininess .54
>             }
>         }

>         geometry Sphere
>         {
>         }
>     }
>}

>Viewpoint
>{
>     fieldOfView .1
>     position 0 0 100

>     description "parallel"
>}

>Viewpoint
>{
>     description "normal"
>}

># end of file.



Wed, 07 Sep 2005 06:44:00 GMT  
 
 [ 4 post ] 

 Relevant Pages 

1. Orthographic/Parallel Projection with Layer2D in Blaxxun Contact

2. Projection in Clarion

3. 3D->2D perspective projection

4. Orhogonal Projection

5. 3D rotation and projection in Assembler

6. Ada-based design analysis tool needed (SLOC projections)

7. Axometric projection in VRML?

8. Need map projection algorithms

9. Looking for map projection algorithms/code

10. AN ENROLMENT PROJECTION PROBLEM

11. Help: Increased Lagrange algorithm with projection

12. CFP: ACPC'96 - parallel DBs and parallel I/O

 

 
Powered by phpBB® Forum Software