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Jason,<br>
<br>
Not that I have the best answer for you (although I am interested in
what you are doing with your reference to <font
face="Verdana, Helvetica, Arial"><span DEFANGED_STYLE="font-size: 12px;">'NEXRAD
RADAR</span></font>'); it seems to me that you may need to set some
threshold to the raster to identify the cells and then do a raster to
vector conversion from which you can identify the polygon centroids.
Just a thought…<br>
<br>
Regards,<br>
Tom<br>
<br>
<br>
Jason Horn wrote:<br>
<blockquote type="cite"
cite="mid72AF1BAC-39C2-4DF1-AED7-6D8D7A5A5C38@bu.edu">
<div DEFANGED_STYLE="margin: 0px;">John, </div>
<div
DEFANGED_STYLE="margin: 0px; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; font-size: 12px; line-height: normal; font-stretch: normal; font-size-adjust: none; min-height: 14px;"><br>
</div>
<div DEFANGED_STYLE="margin: 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: 0px; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; font-size: 12px; line-height: normal; font-stretch: normal; font-size-adjust: none; min-height: 14px;"><br>
</div>
<div DEFANGED_STYLE="margin: 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: 0px;"><font class="Apple-style-span" face="Arial"
size="3"><span class="Apple-style-span" DEFANGED_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: 0px; font-family: Arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 13px; line-height: normal; font-stretch: normal; font-size-adjust: none; min-height: 15px;"><br>
</div>
<div DEFANGED_STYLE="margin: 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
DEFANGED_STYLE="margin: 0px; font-family: Arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 13px; line-height: normal; font-stretch: normal; font-size-adjust: none; min-height: 15px;"><br>
</div>
<div DEFANGED_STYLE="margin: 0px;"><font class="Apple-style-span" face="Arial"
size="3"><span class="Apple-style-span" DEFANGED_STYLE="font-size: 13px;">-
Jason</span></font></div>
<div DEFANGED_STYLE="margin: 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
DEFANGED_STYLE="font-size: 12px;">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
style="font-size: 12px;">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: 14px;">Jason
Horn<br>
</span></font></font><font face="Verdana, Helvetica, Arial"><span
DEFANGED_STYLE="font-size: 12px;"> <br>
<br>
</span></font><font size="4"><font
face="Helvetica, Verdana, Arial"><span DEFANGED_STYLE="font-size: 14px;">Boston
University Department of Biology<br>
</span></font></font><font face="Verdana, Helvetica, Arial"><span
DEFANGED_STYLE="font-size: 12px;"> <br>
<br>
</span></font><font size="4"><font
face="Helvetica, Verdana, Arial"><span DEFANGED_STYLE="font-size: 14px;">5
Cumington Street </span></font></font><font
face="Helvetica, Verdana, Arial"><span DEFANGED_STYLE="font-size: 12px;">Boston,
MA 02215<br>
</span></font><span DEFANGED_STYLE="font-size: 12px;"><font
face="Verdana, Helvetica, Arial"> <br>
<br>
<br>
<br>
<br>
</font></span><font size="4"><font
face="Helvetica, Verdana, Arial"><span DEFANGED_STYLE="font-size: 14px;"><a
href="mailto:jhorn@bu.edu">jhorn@bu.edu</a><br>
</span></font></font><font face="Verdana, Helvetica, Arial"><span
DEFANGED_STYLE="font-size: 12px;"> <br>
<br>
</span></font><font size="4"><font
face="Helvetica, Verdana, Arial"><span DEFANGED_STYLE="font-size: 14px;">office:
617 353 6987<br>
</span></font></font><font face="Verdana, Helvetica, Arial"><span
DEFANGED_STYLE="font-size: 12px;"> <br>
<br>
</span></font><font size="4"><font
face="Helvetica, Verdana, Arial"><span DEFANGED_STYLE="font-size: 14px;">cell:
401 588 2766<br>
</span></font></font><font face="Verdana, Helvetica, Arial"><span
DEFANGED_STYLE="font-size: 12px;"> <br>
<br>
<br>
<br>
</span></font></blockquote>
<font face="Verdana, Helvetica, Arial"><span
DEFANGED_STYLE="font-size: 12px;"><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>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Thomas E Adams
National Weather Service
Ohio River Forecast Center
1901 South State Route 134
Wilmington, OH 45177
EMAIL: <a class="moz-txt-link-abbreviated" href="mailto:thomas.adams@noaa.gov">thomas.adams@noaa.gov</a>
VOICE: 937-383-0528
FAX: 937-383-0033</pre>
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