line in 3d in direction of eigen vector

• To: mathgroup at smc.vnet.net
• Subject: [mg84062] line in 3d in direction of eigen vector
• From: vicky Al Aisa <vickyisai at gmail.com>
• Date: Sat, 8 Dec 2007 05:44:56 -0500 (EST)

```Hello everyone

I was able to a 3d plot  of an  image using this (suggested by someone
of u)

pic=Graphics3D[
Map[{RGBColor @@ (#/255), Point[#]} &, img[[1, 1]], {2}]
]
Show[pic]

Now I was able  to get a line in the direction of eigen vctor by doing
the following
-------------------------------------------------------
ColorDot=Table[0,{ImgSize},{3}];
For[i=1,i<=ImgSize,i++,
ColorDot[[i]]=MeanVector+EigenVectorsColoumn[[1]]*stept[[i]]
]

Graphics3D[Line[ColorDot]]

---------------------------------------------------------

I was able to get a line with this  , but that was black, I wanted a
colored line...color depending on the coordinate( taken as RGB)

So I did the following

---------------------------------------------
pic=Graphics3D[
Map[{RGBColor @@ (#/255), Point[#]} &, ColorDot]
]
Show[pic]
------------------------------------------------

But problem with this is that, to compute ColorDot vector .,,I started
from mean, and took a positive and negative step( taken as stept
above)  to go forward and backward from mean,,,,,,,so ColorDot table
has coordinates but some of those are negative..and

So the above gives me half line and tat too just blue colored....
i get error
Graphics::realu: Argument in expr is not a real number between 0 and
1.

Thank You

vicky  Al Aisa

```

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