<div class="gmail_quote">On Thu, Nov 26, 2009 at 10:04 AM, renlishen <span dir="ltr"><<a href="mailto:renlishen@gmail.com">renlishen@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
David, thanks~<br>
I find the key point to my question...<br>
If I don't use the vtkPolyDataNormals' SplittingOff()<br>
I get more points and normals like this<br>
pic1:<br>
<a href="http://old.nabble.com/file/p26530678/11.png" target="_blank">http://old.nabble.com/file/p26530678/11.png</a><br>
<br>
but when I use SplittingOff()<br>
I get the correct number of points and normals<br>
pic2:<br>
<a href="http://old.nabble.com/file/p26530678/22.png" target="_blank">http://old.nabble.com/file/p26530678/22.png</a><br>
<br>
<br>
but I don't know why vtkPolyDataNormals need to "splitting" the edge.....<br>
anyway~thanks again for your replying...^^<br>
<br>
<br>
p.s. my data has 5 points and 6 cell(face)<br>
After using SplittingOff() ----> 5 points and 5 normals(pic2)<br>
If no use SplittingOff() ----> 16 points and 16 normals(pic1)<br>
<font color="#888888"><br></font></blockquote><div><br>It looks to me like SplittingOff() is finding the average normal at each point. You can see this by looking at the tip of your pyramid - the normal that exists in 22.png does not exist in 11.png - it is the average of the 4 vectors. With SplittingOn() - it looks like it is simply using the normal of the face. Since each point is connected to multiple faces, there are multiple normals.<br>
<br>Hope that helps.<br><br clear="all">Thanks,<br><br>David <br></div></div><br>