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 CAD / Ray-Tracing / 1876
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Subject: 
Re: Can anyone help by suggesting some lighting tips?
Newsgroups: 
lugnet.cad.ray
Date: 
Sun, 13 Jul 2003 00:49:52 GMT
Viewed: 
2039 times
  
In lugnet.cad.ray, Will Hess wrote:
In lugnet.cad.ray, Allan Bedford wrote:
Interestingly, the image above does have one light that is not shadowless.
However, there are only shadows on the engine, not below it.  Is that
because I have removed the reference to the floor include file?

You got it.

So.... is there a way to create an invisible floor?  One that you don't see (as
in it's the same white color as the background) but will allow you to project a
shadow of the vehicle?

But wait... your renders (which I am trying hard to copy the style of) don't use
a floor either, is that right?  :)

Two things concern me.

1)  The graininess seen on things like the controls for the pump panel. (The
1x2 printed tile near the center of the pumper).  And things like the front
headlights.  Is this effect a result of collisions?  Or problems with LGEO parts
not being available for these pieces?  Or a bit of both?

You might want to check your DAT / LDR file, as it looks like the part is
rendered in a transparent-gray instead of a solid gray.

I think I fixed it.  I think it's caused by part collision.  I find that little
1x2 grille piece tricky.  It looks like it's far enough out from the pieces it's
attached to, but I keep forgetting about the groove on the bottom edge.  I think
the middle strip keeps colliding with the studs below.  By moving it out just a
fraction of an inch, it seems to improve the quality greatly.

2)  The angle or perspective of the engine bothers me.  It is a short vehicle,
but the render really makes it look really stubby.  I've read about the
'orthographic' setting, but must admit to not understanding it.  Is there some
way to alter the 'look' of the image, so the engine looks a bit more realistic
in its proportions?

This is where I'll continue our discussion from lugnet.town :-)

The 'orthographic' setting eliminates the sense of perspective from the
rendering.  L3P-generated POV files have this turned off, but enabling it is
a piece of cake.  Your camera code will have a line like this:

//orthographic

Just remove the slashes and render.  You'll notice that your camera has
appeared to move and is no longer looking at the center of your model.  This
is what  use the translate commands for.  I'll describe those in a minute,
but there's one more camera setting you might want to play with.

Tried removing the slashes, but it came back with one of those 'expecting you to
be smarter' error messages.  So I put the slashes back in and it stopped
complaining.  :)

If you want to zoom in or away from your model, adjust numerical portion of
the following setting:

#declare PCT = -20; // Percentage further away

Negative numbers zoom in while positive numbers zoom out.

Now, about model positioning.  Moving cameras and lights is a serious pain
in the rear to me, as you need to adjust both positions and angles.  Moving
the model is MUCH easier, but you'll have to insert some code to do so.
Don;t worry...it's not hard :-)

For this example... which is the one I'm currently struggling with... I simply
allowed LPub to send the position of the model and the camera to POV-Ray.  I
find I can understand the parameters better in LPub.  I'm happy with this
particular angle, but have a couple problems I can't seem to fix:

http://www.apotome.com/lego/misc/ladder110-sun.jpg

1)  The 'sun' effect is very evident.  However, it's so strong coming in from
the top right, that it casts a nasty shadow over the front of the cab, plunging
it into darkness.  I've tried numerous times to add a low powered light, coming
in from the left, parallel with truck, but I can't seem to correct this problem.

2)  What's with the jagged lines running between the bricks?  Sometimes I get
them (such as here) and sometimes I don't, which makes things look much more
realistic.  Problem is, I can't seem to figure out what does or does not cause
them.

3)  The white of the ladder still looks bleached out to me.  You should be able
to see the inner sections of the ladder (two plates high, of pieces) through the
lattice pieces.  In some versions, I've been able to brighten them, but at the
expense of scorching the white ladder even worse.  In some versions, I've had it
so bad that the back end of the ladder simply blends into the white background.

Any thoughts or suggestions are once again greatly appreciated.

Move to the bottom of your POV file and start scrolling up until you see a
line that starts with "object."  This will be just above the floor code (if
you have one) or the background code (if there's no floor).  Paste the
following just inside the bracket at the end of the line:

<translate 0,0,0>

The end of the line should look like this:

#else texture #end { Color7 } translate <0, 0, 0>}

Moving the model is a matter of plugging values in to replace the zeros in
the translate command.  The first number adjusts the horizontal position of
the model.  Negative values move the model towards the lower right of the
scene, positive ones move towards the upper left.  The second number adjusts
the vertical position.  Negative numbers move the model up, positive numbers
move it down.  The last number affects the depth of the model, and works
much like the first one.  In this case, positive numbers move the model
towards the upper right while negative ones move to the lower left.

Another neat trick is the rotate command, but we can cover that one later

I'm going to try all that.... once I get a better handle on the lighting issues.
:)

Thanks!!!

Allan B.



Message has 1 Reply:
  Re: Can anyone help by suggesting some lighting tips?
 
(...) see (as (...) project a (...) Make a white floor and use the translate commands to move your model away from the seam where the floor and background meet. (...) don't use (...) Nope. A bare floor doesn't do much for me, so I leave it out. (...) (21 years ago, 13-Jul-03, to lugnet.cad.ray)

Message is in Reply To:
  Re: Can anyone help by suggesting some lighting tips?
 
(...) You got it. (...) (The (...) front (...) parts (...) You might want to check your DAT / LDR file, as it looks like the part is rendered in a transparent-gray instead of a solid gray. (...) vehicle, (...) some (...) realistic (...) This is (...) (21 years ago, 12-Jul-03, to lugnet.cad.ray)

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