ArcGIS9.0为何不能创建泰森多边形？

<P>  <FONT face=宋体>如题，我在ArcMap9.0中调用ArcToolbox模块，希望创建泰森多边形(thiessen polygon)，点状coverage文件我已经准备好，但是在ArcMap9.0的命令窗口(command windows)中试图输入函数：thiessen <input_coverage>   <output_coverage> 时，系统却没有提供该函数！我曾经在ArcGIS8.x中实现过泰森多边形的创建，其方法是调用ArcToolbox的现成菜单：<FONT size=2>analysis tools/proximity/create thiessen polygons，可以成功。   为何在ArcGIS9.0中既没有现成的菜单，也没有相应的函数？惑。。。</FONT></FONT></P>

<P>好象在ArcInfo ws中才有了</P><P>帮助中说：</P><P>Command line syntax</P><P>Thiessen_arc <in_cover> <out_cover> {proximal_tolerance}

<B>Parameters</B>
<TABLE cellPadding=5 width="100%" border=0><TR><TH width="40%"><B>Expression</B></TH><TH width="60%"><B>Explanation</B></TH></TR><TR><TD class=info><in_cover></TD><TD class=info align=left><P>The <a>coverage</A> which must have a point feature attribute table created by BUILD with the POINT option.</P></TD></TR><TR><TD class=info><out_cover></TD><TD class=info align=left><P>The polygon coverage in which the Thiessen proximal polygons will be produced.</P></TD></TR><TR><TD class=info>{proximal_tolerance}</TD><TD class=info align=left><P>Tolerance used to eliminate <B>Input Coverage</B> points that fall within the specified distance of other <B>Input Coverage</B> points. The default <B>Proximal Tolerance</B> is the machine precision of the computer.</P></TD></TR></TABLE><B>Command Line Example</B>

</P><PRE>thiessen  buildings_pt  out_buildings  2</PRE>

是的，我看帮助也是这样写的，但是系统没有提供该函数