Lighting problems 
Author Message
 Lighting problems

Well, all I know is what I have read. I believe that the book "Core Web3D" (I
think that's where I read it) states that most vrml applets/plugins can
effectively render only 8 light sources at a time. My guess is that your 15
light sources are part of your problem. Try doing it with 8 and make sure you
turn off your headlight as well. Also the more polygons that you have in your
ice surface the more realistically it will reflect light. a giant sheet of ice
created from just one polygon will look like {*filter*}compared to a sheet of ice
divided up into 200 or more. The same will go for your rink boards and
anything else. Of course, you'll always want to keep your frame rate in mind
when adding more polygons to your ice arena.

Aaron

Quote:

> Hi

> I wonder if anyone can help solve my lighting problems. I have created a
> virtual ice rink and I am trying to light the rink from 15 lights that
> are contained above the ice surface. But I can't seem to acheive the
> effect that I want. I have tried the lights in every available position
> and the rink still looks dark and patchy!!!!

> I have attached a zip file of the ice rink and the main file is
> main5.wrl and that is also the file that contains the lights that I have
> added. I know that the lights are in the correct place as they are in
> the same place as the shapes that are meant to represent the lights.

> Any help would be grately appreciated, even some harsh critacism of the
> design!!!!!

> Bryan

>   ------------------------------------------------------------------------
>                Name: rink.zip
>    rink.zip    Type: Zip Compressed Data (application/x-zip-compressed)
>            Encoding: base64

--
Aaron Bergstrom

WWW Site Developer
Plant Sciences - http://www.*-*-*.com/
Virtual Cell - http://www.*-*-*.com/
Archaeology Technologies Lab - http://www.*-*-*.com/
North Dakota State University


Sun, 17 Aug 2003 23:30:35 GMT  
 Lighting problems
I also took a look a your vrml code. I notice that for most things you used
extrusions.  Extrusions, especially the inside, are funny light reflectors. I
would model it using indexed face sets. Also, all the parts of your ice rink,
the lines, the dots, etc... are at the same Y translation. If you'd like them
to show up better, you should put them slightly above the level of the ice.

--
Aaron Bergstrom

WWW Site Developer
Plant Sciences - http://www.ndsu.edu/ndsu/abergstr/
Virtual Cell - http://vcell.ndsu.edu/
Archaeology Technologies Lab - http://atl.ndsu.edu/
North Dakota State University



Sun, 17 Aug 2003 23:44:58 GMT  
 Lighting problems

I checked your model and there is a number of problems with it; otherwise the
model is nice and desserve more little fix-up.
1 - you have *WAY TOO MUCH* lights... Even, you use only SpotLight, which are
the most expensive one... and most of them do not contribute to the lighting..
:-)
To acheive the result you want, you'll better with only *one*
directionnalLight over the rink and have some more around. Or you can fake
them by "burning" them into the indexed face set itself trough a Color node -
radiosity like method.
2 - for the rink ice, it is composed from a multitude of polygons around the
curved corner while all the center is made from only two triangle: even with
hundreds of lights, it wont show any "spotted" halo - to have a distinct light
beam on a shape, this shape must contain many facets so each facet get lit
differently to acheive the effect.
3 - the stripes have to be over the ice; at same level it give zbuffering
problems - the rendering engine wobble between one or another geometry.
Another solution is to "cut" the ice geometry and replace with stripe geometry
but that will lead to too many polygons for nothing. Another way is to use
texture with transparent background or divide the ice in sub section and use
different transparent texture mapped element that you'll reuse according to
rink symmetry. Can divide by center, blue zone, corner zone and blue & corner
reused the other side.
I suggest a "sandwich" approach; the external brown floor should stay below in
one big piece, then, a few centimeter up, the ice + texture *or* since the
stripe & cicle are nice, here a more expensive way - although less than what
you acually have - 3 part ice:
below, white sheet made of big pieces, up, the stripes & circle geometry, and
on top, a sheet of almost transparent glossy (high specular) sheet made of
more polygons - a mesh. That would simulate more ice aspect.

Lastly, since there is lot of geometry inside, maybe you could do a bit of
management; some visibility sensor could be very well appropriate here to
switch out part of the scene that is assured not to be seen. Navigation will
be easier. Talking about navigation, I noticed that your dimention are very
big so you have to adjust navigation info to navigate more faster.

Also, there is seem a "roof" over the rink but its face are transparent from
under.

I can give a bit of help for the geometry of the rink. But I'll have to sleep
before...

Sylvain Carette
VRML designer-composer

Quote:

> Hi

> I wonder if anyone can help solve my lighting problems. I have created a
> virtual ice rink and I am trying to light the rink from 15 lights that
> are contained above the ice surface. But I can't seem to acheive the
> effect that I want. I have tried the lights in every available position
> and the rink still looks dark and patchy!!!!

> I have attached a zip file of the ice rink and the main file is
> main5.wrl and that is also the file that contains the lights that I have
> added. I know that the lights are in the correct place as they are in
> the same place as the shapes that are meant to represent the lights.

> Any help would be grately appreciated, even some harsh critacism of the
> design!!!!!

> Bryan

>   ------------------------------------------------------------------------
>                Name: rink.zip
>    rink.zip    Type: Zip Compressed Data (application/x-zip-compressed)
>            Encoding: base64



Mon, 18 Aug 2003 06:29:17 GMT  
 Lighting problems


I checked your model and there is a number of problems with it; otherwise
the model is nice and desserve more little fix-up.
1 - you have *WAY TOO MUCH* lights... Even, you use only SpotLight, which
are the most expensive one... and most of them do not contribute to the
lighting.. :-)
To acheive the result you want, you'll better with only *one*
directionnalLight over the rink and have some more around. Or you can fake
them by "burning" them into the indexed face set itself trough a Color
node - radiosity like method.

To add to what Sylvain has said:

you might also try making the ice up of two semitranparent sheets with color
fields.
set transparency to 0.5 on each.
you coul also try putting a white sheet underneath the layers. Also put the
stipes in one of the layers. Also the layers should be 0.02 appart.

This is the lighting set up I use. Alter the intensity values as needed.

DEF Front DirectionalLight {
 intensity 0.9

Quote:
}

DEF Rear DirectionalLight {
 intensity 0.7
 direction 0 0 1
Quote:
}

DEF Top DirectionalLight {
 intensity 5
 direction 0 -1 0
Quote:
}

DEF UnderSide DirectionalLight {
 intensity 0.4
 direction 0 1 0
Quote:
}

DEF Right DirectionalLight {
 intensity 1
 direction 1 0 0
Quote:
}

DEF Left DirectionalLight {
 intensity 0.6
 direction -1 0 0
Quote:
}

DEF Sun SpotLight {
 location -50 100 -25
 direction 0.3 -1 0
 intensity 2
 radius 200
Quote:
}



Tue, 19 Aug 2003 01:10:12 GMT  
 Lighting problems

[...]

Quote:
> Lastly, since there is lot of geometry inside, maybe you could do a
> bit of management; some visibility sensor could be very well
> appropriate here to switch out part of the scene that is assured not
> to be seen.

Just a question about this. Do you mean it is possible to tell the
plugin not to render parts of the scene, which are defined by whatever
for conditions??
If I understand this right, maybe you could explain it a little bit
further?

Thanx in advance
bye
Matthias



Mon, 18 Aug 2003 23:09:06 GMT  
 Lighting problems

Quote:


> [...]

> > ... switch out part of the scene that is assured not
> > to be seen.

> Just a question about this. Do you mean it is possible to tell the
> plugin not to render parts of the scene, which are defined by whatever
> for conditions??

Someone else might take the time to go into detail for you, but you can
find out about this for yourself by checking out the "Switch" node in
the VRML97 specification. Your geometry variants are stored as children
of the Switch node in its "choice" MFNode exposedField. You use it under
control of a Script. The Script would have an integer eventOut which
would be ROUTEd to the whichChoice exposedField of the Switch node.

See the Annotated VRML97 Reference Manual:
http://www.best.com/~rikk/Book/

- Paul
***********************************
Paul S. Hoffman
Senior Interface Designer, Cognetics Corporation

Company URL - http://www.cognetics.com
Personal URL - http://pluto.njcc.com/~paulsam
609-799-5005 ext.237 - FAX 609-799-8555



Tue, 19 Aug 2003 07:19:10 GMT  
 
 [ 7 post ] 

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