<HTML><BODY DEFANGED_STYLE="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><DIV DEFANGED_STYLE="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">John, </DIV><DIV DEFANGED_STYLE="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Thanks for the response. By center, I did not mean the geometric centroid, rather the center of intensity based on pixel values. For reference, if you've ever used IDRISI, something like their CENTER module:</DIV><DIV DEFANGED_STYLE="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">"<FONT class="Apple-style-span" face="Arial" size="3"><SPAN class="Apple-style-span" DEFANGED_STYLE="font-size: 13px;"><B>center</B></SPAN></FONT><FONT class="Apple-style-span" face="Arial"> </FONT></DIV><DIV DEFANGED_STYLE="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Arial" size="3"><SPAN class="Apple-style-span" style="font-size: 13px;">Compute mean center (weighted or not) of a point distribution and standard radius (the two dimensional equivalent of a standard deviation)."</SPAN></FONT></DIV><DIV DEFANGED_STYLE="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Arial; min-height: 15px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Arial" size="3"><SPAN class="Apple-style-span" DEFANGED_STYLE="font-size: 13px;">I have worked with folks in the Geography department, and I know that this sort of thing is relatively easy mathematically, I just wanted to know if it was possible with GRASS 6.0 as it is.</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Arial; min-height: 15px; "><BR></DIV><DIV DEFANGED_STYLE="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Arial" size="3"><SPAN class="Apple-style-span" style="font-size: 13px;">- Jason</SPAN></FONT></DIV><DIV DEFANGED_STYLE="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Arial" size="3"><SPAN class="Apple-style-span" DEFANGED_STYLE="font-size: 13px;"><BR class="khtml-block-placeholder"></SPAN></FONT></DIV><BR><DIV><DIV>On Jun 2, 2005, at 3:51 PM, Jonathan Greenberg wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"> <FONT face="Verdana, Helvetica, Arial"><SPAN style="font-size:12.0px">Jason:<BR> <BR> What do you mean by center? Are you referring to a geometric centroid, or the brightest pixel value falling within a poly, or something else? Have you chatted with any of the RS people at BU? BU has one of the best remote sensing programs in the country (its also my alma mater). <BR> <BR> --j<BR> <BR> <BR> On 6/2/05 12:42 PM, "Jason Horn" <<A href="mailto:jhorn@bu.edu">jhorn@bu.edu</A>> wrote:<BR> <BR> </SPAN></FONT><BLOCKQUOTE type="cite"><FONT face="Verdana, Helvetica, Arial"><SPAN DEFANGED_STYLE="font-size:12.0px">Does anyone know of a way to calculate the center of a shape in a raster file based on shape and pixel values? For example, imagine a NEXRAD RADAR image showing a storm cloud. Could GRASS be used to calculate the center of the cloud? I'm not having any luck finding a grass raster function to do this.<BR> <BR> Thanks, <BR> <BR> - Jason<BR> <BR> <BR> <BR> <BR> </SPAN></FONT><FONT size="4"><FONT face="Helvetica, Verdana, Arial"><SPAN DEFANGED_STYLE="font-size:14.0px">Jason Horn<BR> </SPAN></FONT></FONT><FONT face="Verdana, Helvetica, Arial"><SPAN style="font-size:12.0px"> <BR> <BR> </SPAN></FONT><FONT size="4"><FONT face="Helvetica, Verdana, Arial"><SPAN style="font-size:14.0px">Boston University Department of Biology<BR> </SPAN></FONT></FONT><FONT face="Verdana, Helvetica, Arial"><SPAN style="font-size:12.0px"> <BR> <BR> </SPAN></FONT><FONT size="4"><FONT face="Helvetica, Verdana, Arial"><SPAN DEFANGED_STYLE="font-size:14.0px">5 Cumington Street </SPAN></FONT></FONT><FONT face="Helvetica, Verdana, Arial"><SPAN DEFANGED_STYLE="font-size:12.0px">Boston, MA 02215<BR> </SPAN></FONT><SPAN DEFANGED_STYLE="font-size:12.0px"><FONT face="Verdana, Helvetica, Arial"> <BR> <BR> <BR> <BR> <BR> </FONT></SPAN><FONT size="4"><FONT face="Helvetica, Verdana, Arial"><SPAN style="font-size:14.0px"><A href="mailto:jhorn@bu.edu">jhorn@bu.edu</A><BR> </SPAN></FONT></FONT><FONT face="Verdana, Helvetica, Arial"><SPAN style="font-size:12.0px"> <BR> <BR> </SPAN></FONT><FONT size="4"><FONT face="Helvetica, Verdana, Arial"><SPAN style="font-size:14.0px">office: 617 353 6987<BR> </SPAN></FONT></FONT><FONT face="Verdana, Helvetica, Arial"><SPAN style="font-size:12.0px"> <BR> <BR> </SPAN></FONT><FONT size="4"><FONT face="Helvetica, Verdana, Arial"><SPAN DEFANGED_STYLE="font-size:14.0px">cell: 401 588 2766<BR> </SPAN></FONT></FONT><FONT face="Verdana, Helvetica, Arial"><SPAN DEFANGED_STYLE="font-size:12.0px"> <BR> <BR> <BR> <BR> </SPAN></FONT></BLOCKQUOTE><FONT face="Verdana, Helvetica, Arial"><SPAN DEFANGED_STYLE="font-size:12.0px"><BR> <BR> <BR> -- <BR> Jonathan A. Greenberg, PhD<BR> NRC Research Associate<BR> NASA Ames Research Center<BR> MS 242-4<BR> Moffett Field, CA 94035-1000<BR> 650-604-5896<BR> AIM: jgrn307<BR> MSN: <A href="mailto:jgrn307@hotmail.com">jgrn307@hotmail.com</A><BR> </SPAN></FONT> </BLOCKQUOTE></DIV><BR></BODY></HTML>