[x3d-public] projective texture mapping (PTM) review

Roy Walmsley roy.walmsley at ntlworld.com
Fri Jul 24 02:43:52 PDT 2015


Thanks for the details below. Would it be possible, please, to have the
latest version of the slides. I am interested in following your discussions
and have considered joining your meeting. However, they occur about
0200-0300 hours for me in the UK so are not practical.

Regards,

Roy

-----Original Message-----
From: x3d-public [mailto:x3d-public-bounces at web3d.org] On Behalf Of Don
Brutzman
Sent: 23 July 2015 03:05
To: Kwan-Hee Yoo
Cc: 'Myeong Won Lee'; 'X3D Graphics public mailing list'
Subject: Re: [x3d-public] projective texture mapping (PTM) review

Thanks for discussion during today.

Comments:

a. fix slide 12 to match slides 13, 14, 15

b. near, far -> nearDistance, farDistance

c. no default value for aspectRatio since it is an output field

d. add common fields to X3DTextureProjectorNode:  aspectRatio, nearDistance,
farDistance

I think:

e. add textureTransform to allow modification of image texture.

f. aspectRatio is an output value that describes the width/height ratio of
the texture image (not the projection volume).

g. fieldOfView relates to projection volume, and does not warp texture.
This similar functionality to Viewpoint/OrthoViewpoint fieldOfView, which
define extents and do not warp anything.

Also: please add a slide about the maturity/availability of your FreeWrl
implementation.  Then we can add these draft nodes to the "wish list" for
X3DOM implementation, perhaps someone at SIGGRAPH will want to help.

Also: if possible please provide a url to your demo video.  Alternatively we
can post it online for you.

Thank you for your steady excellent progress.


On 7/22/2015 8:34 AM, Kwan-Hee Yoo wrote:
> Hi, Don
>
> The updated content according to last meeting results is in an attached
file.
> We would like to have tomorrow meeting at July 23, 10:00 AM Korean Time.
>
> See you.
>
> Best Regards,
> Kwan-Hee Yoo
>
>
> -----Original Message-----
> From: Don Brutzman [mailto:brutzman at nps.edu]
> Sent: Thursday, June 25, 2015 11:39 AM
> To: khyoo at chungbuk.ac.kr
> Cc: 'Myeong Won Lee'; 'Richard F. Puk'; X3D Graphics public mailing list
> Subject: Re: projective texture mapping (PTM) review
>
> PTM review meeting today.  Attendees Kwan Hee Yoo, Dick Puk, Don Brutzman.
>
> Getting closer for sure.  Minutes:
>
> 1. slide 11.  Rename X3DProjetiveTextureNode (in green area) to
X3DTextureProjectorNode for consistency with the other nodes, and the rest
of the slide.
>
> =======================================
>
> 2. slides 11-13.
>
> 2.a. We discussed whether to align field names with those defined for
X3DViewpointNode, Viewpoint, and OrthoViewpoint.
>
> For example, this might change location -> position, direction ->
orientation, etc.
>
> However, DirectionalLight use SFVec3f direction and PointLight uses
SFVec3f location.  Spotlight uses direction and location.
>
> We discussed how these projector nodes are most similar to lights, not as
much with viewpoints.
>
> So suggested field naming would be to stay the same as lights: location
and direction.
>
> =======================================
>
> 2.b. Next fields:
>
> - TextureProjectorPerspective fieldOfView should similar to Viewpoint
SFFloat fieldOfView, and
>
> - TextureProjectorParallel width/height should change instead to match
OrthoViewpoint MFFloat (4-tuple) fieldOfView.
>
> Rationale: we match fieldOfView for each node to be similar to the
corresponding Viewpoint nodes.  This is simpler both for computation, and
also simpler for authors to view the projector results.  For example:
>
> - Viewpoint node could accompany a TextureProjectorPerspective, and
>
> - OrthoViewpoint node could accompany TextureProjectorParallel.
>
> =======================================
>
> 2.c. Next field:
>
> aspectRatio not needed per se, because it is implicit in the definition of
the texture node (ImageTexture/MovieTexture/PixelTexture).  Each of these
nodes has a width and height built into the texture already.
>
> We discussed how there are many ways to transform a texture; upVector and
perhaps some field for warping are complicated possibilities.
>
> View volume is independent of texture being applied.
>
> We discussed how simplest approach may be to add a TextureTranform (center
rotation scale translation, all in U-V texture coordinates).  This would
eliminate upVector and aspectRatio.  It would also likely make use of the
contained texture simpler for both players and authors since it would be
consistent with other texture use.
>
> In other words, a texture node in combination withTextureTransform results
in another texture.   So it remains simple.
>
> =======================================
>
> 3.  slide 14:
>
> "How do we reflect lighting information into projective texture mapping
nodes?"
>
> The fields above seem to align the texture in some ways similar to a light
source.
>
> We do not need to adjust the lighting equations in the specification to
include projector contributions, because they are not lights per se.  Rather
they are applying textures to materials, which are later lit separately by
the lights.
>
> =======================================
>
> 4.  Meanwhile, possibly aspectRatio (or maybe SFVec2f imageSize) ought to
be an outputOnly field... this might benefit authors using any of the
texture nodes.
>
> =======================================
>
> 5. References:
>
> 17 Lighting component
> (X3DLightNode DirectionalLight PointLight Spotlight)
http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components
/lighting.html
>
>
> 18 Texturing component
> (X3DTexture2DNode X3DTextureTransformNode ImageTexture MovieTexture
TextureTransform)
http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components
/texturing.html
>
>
> 23 Navigation component
> (X3DViewpointNode, Viewpoint, and OrthoViewpoint)
http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components
/navigation.html
>
> =======================================
>
> 6. We plan to meet again via teleconference on July 22, and hopefully
again at SIGGRAPH.
>
> 	http://www.web3d.org/calendar/month/2015-07
>
> Excellent progress today... kam sa hab ni da, thank you!
>
> 	https://translate.google.com/#en/ko/thank%20you
>
> all the best, Don
>


all the best, Don
-- 
Don Brutzman  Naval Postgraduate School, Code USW/Br       brutzman at nps.edu
Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA   +1.831.656.2149
X3D graphics, virtual worlds, navy robotics http://faculty.nps.edu/brutzman

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