shrug-l: Question du jour
Nonie Castro
nonie_castro@coxtarget.com
Fri, 30 Sep 2005 13:17:16 -0400
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If we are taking a vote - I don't mind the back and forth in real time.=20
________________________________
From: shrug-l-admin@lists.dep.state.fl.us =
[mailto:shrug-l-admin@lists.dep.state.fl.us] On Behalf Of Joe Noble
Sent: Friday, September 30, 2005 1:06 PM
To: Sykes, John; Geographic Systems LLC; shrug-L@lists.dep.state.fl.us
Subject: RE: shrug-l: Question du jour
=09
=09
I would like to suggest some sort of protocol that folks post their =
question, once, then those that have a possible solution contact the =
person directly not numerous e-mails to the entire user list. After a =
solution has been decided, the original person posting the question =
could sum the solutions in one e-mail back to the board. Sorry but my =
e-mail has been looking like a GIS chat room as of late. Joe
=20
Joe Noble=20
GIS/IS Coordinator=20
Tall Timbers Research Station
850-893-4153 x-232
=20
=09
________________________________
From: shrug-l-admin@lists.dep.state.fl.us =
[mailto:shrug-l-admin@lists.dep.state.fl.us] On Behalf Of Sykes, John
Sent: Friday, September 30, 2005 12:41 PM
To: Geographic Systems LLC; shrug-L@lists.dep.state.fl.us
Subject: RE: shrug-l: Question du jour
=20
That's a good website. From it I gather that if I want BOTH the =
distances and azimuths to my sampling locations from the site center to =
be the most accurate, the Azimuthal Equidistant projection is the best =
solution.
=20
I came up with part of the rest of your solution on my own, however, =
I'm having trouble rotating it through 360=B0.
=20
Another solution I thought of, is setting up the sector lines in an =
AutoCad file, then importing it into my map with a world file using the =
center point and the intersection of the first radial with the 10 mile =
buffer ring as the two points.
-- John=20
=20
=20
=09
________________________________
From: Geographic Systems LLC [mailto:info@geographicsystems.com]=20
Sent: Friday, September 30, 2005 12:19 PM
To: Sykes, John
Subject: RE: shrug-l: Question du jour
Hi John,
=20
I will try to address the first part of your question (drawing lines =
out 10 miles at 11.25 degree increments) and the last part =
(projections). The second part of your question (rhumb line from site =
point to sampling location) may require more research.
=20
Projections - definitely play a part in spatial accuarcy. My guess is =
you want a projection that preserves direction and distance. A good =
place to start is the summary tables at the bottom of the map projection =
poster, http://erg.usgs.gov/isb/pubs/MapProjections/projections.html.=20
=20
Drawing lines of specific distance and angle. You can do this manually =
when you sketch a line. With Task set to Create New Feature and Target =
your line feature class, click the sketch tool (pencil) and click on the =
first point of your line. Then right click away from the sketch and =
select "Direction" (or CTRL-A) specify an angle (0 being horizontal - ie =
"11.25") and then right click away from sketch again and select "Length" =
(or CTRL-L) ie "2mi" ("mi" for miles). Or you can enter both the first =
time you right click by selecting "Direction/Length" (or CTRL-G). Check =
out online help for "Creating segments using angles and lengths".
=20
Miguel Garriga
Geographic Systems, LLC
www.geographicsystems.com
407-261-0451
cel 321-279-6019
=09
________________________________
From: shrug-l-admin@lists.dep.state.fl.us =
[mailto:shrug-l-admin@lists.dep.state.fl.us] On Behalf Of Sykes, John
Sent: Friday, September 30, 2005 10:21 AM
To: shrug-L@lists.dep.state.fl.us
Subject: shrug-l: Question du jour
=20
Since we (collectively) solved the question I had yesterday, here's a =
new one (put on your thinking caps - this one's tougher!).
Problem=20
When establishing environmental sampling locations around a site, we =
like to ensure that the various distance buffer rings are evenly covered =
(e.g., in this case: "site boundary" to 2 miles, 2 - 5 miles and 5 - 10 =
miles. This is simple to create and check with the standard multiple =
buffer tool in ArcToolbox.
However, we also like to check that the 16 compass sectors around the =
site have also been evenly covered*. These 22-1/2=B0 sectors are =
centered on N, NNE, NE, ENE, E, ESE, SE, SSE, S, SSW, SW, WSW, W, WNW, =
NW and NNW.
So, what I would like to do is to create these sectors visually, by =
drawing a line from the origin (an arbitrary "center" point on the site) =
out to 10 miles starting at 11-1/4=B0 compass heading, then rotate =
around 22-1/2=B0 and draw a line, until the 16 sectors are visually =
defined.
Any suggestions as how this can be done (easily)? Previously, when =
doing this in AutoCad, I used a radial copy command. I haven't noticed =
a similar command in ArcGIS.
Finally, once the sampling location is selected (and the lat/long of =
that location determined), we need to be able to determine and list the =
distance and azimuth (rhumb line) from that arbitrary "center" point on =
the site to the sampling location and put it into the sampling location =
attributes table (in the past, I've done this using the NGS "Inverse" =
program [fudging the rhumb line from the great circle azimuths] using a =
batch file input/output) for atmospheric dispersion modeling. However, =
I don't see any easy way to do this with ArcInfo (especially on a batch =
file basis). Any suggestions?
Finally, food for thought -- How does the projection being used effect =
the accuracy of all of this? Normally we use Albers (equal area) or =
Mercator (which gives the most accurate rhumb lines), but is there a =
better projection to use to obtain accurate distances & azimuths? I =
understand from the reading I've done that these functions may be rather =
projection-sensitive.
-- John=20
*Sometimes if there is a prevailing wind bias, we'll bias our sampling =
locations to that prevailing wind direction, but in the current case =
there is no strong prevailing wind direction - the annual wind rose =
shows an almost random 360=B0pattern.
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<DIV dir=3Dltr align=3Dleft><FONT face=3D"Trebuchet MS" size=3D2><SPAN=20
class=3D405321617-30092005>If we are taking a vote - I don't mind the =
back and=20
forth in real time. </SPAN></FONT></DIV><BR>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px =
solid; MARGIN-RIGHT: 0px">
<DIV class=3DOutlookMessageHeader lang=3Den-us dir=3Dltr align=3Dleft>
<HR tabIndex=3D-1>
<FONT face=3DTahoma size=3D2><B>From:</B> =
shrug-l-admin@lists.dep.state.fl.us=20
[mailto:shrug-l-admin@lists.dep.state.fl.us] <B>On Behalf Of </B>Joe=20
Noble<BR><B>Sent:</B> Friday, September 30, 2005 1:06 PM<BR><B>To:</B> =
Sykes,=20
John; Geographic Systems LLC; =
shrug-L@lists.dep.state.fl.us<BR><B>Subject:</B>=20
RE: shrug-l: Question du jour<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=3DSection1>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">I would =
like to=20
suggest some sort of protocol that folks post their question, once, =
then those=20
that have a possible solution contact the person directly not numerous =
e-mails=20
to the entire user list. After a solution has been decided, the =
original=20
person posting the question could sum the solutions in one e-mail back =
to the=20
board. Sorry but my e-mail has been looking like a GIS chat room =
as of=20
late. Joe<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<DIV>
<P class=3DMsoAutoSig><FONT face=3D"Times New Roman" color=3Dnavy =
size=3D3><SPAN=20
style=3D"FONT-SIZE: 12pt; COLOR: navy">Joe Noble =
<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoAutoSig><FONT face=3D"Times New Roman" color=3Dnavy =
size=3D3><SPAN=20
style=3D"FONT-SIZE: 12pt; COLOR: navy">GIS/IS Coordinator=20
<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoAutoSig><FONT face=3D"Times New Roman" color=3Dnavy =
size=3D3><SPAN=20
style=3D"FONT-SIZE: 12pt; COLOR: navy">Tall Timbers Research=20
Station<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoAutoSig><FONT face=3D"Times New Roman" color=3Dnavy =
size=3D3><SPAN=20
style=3D"FONT-SIZE: 12pt; COLOR: navy">850-893-4153 =20
x-232<o:p></o:p></SPAN></FONT></P></DIV>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<DIV>
<DIV class=3DMsoNormal style=3D"TEXT-ALIGN: center" =
align=3Dcenter><FONT=20
face=3D"Times New Roman" size=3D3><SPAN style=3D"FONT-SIZE: 12pt">
<HR tabIndex=3D-1 align=3Dcenter width=3D"100%" SIZE=3D2>
</SPAN></FONT></DIV>
<P class=3DMsoNormal><B><FONT face=3DTahoma size=3D2><SPAN=20
style=3D"FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: =
Tahoma">From:</SPAN></FONT></B><FONT=20
face=3DTahoma size=3D2><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Tahoma">=20
shrug-l-admin@lists.dep.state.fl.us=20
[mailto:shrug-l-admin@lists.dep.state.fl.us] <B><SPAN=20
style=3D"FONT-WEIGHT: bold">On Behalf Of </SPAN></B>Sykes, =
John<BR><B><SPAN=20
style=3D"FONT-WEIGHT: bold">Sent:</SPAN></B> Friday, September 30, =
2005 12:41=20
PM<BR><B><SPAN style=3D"FONT-WEIGHT: bold">To:</SPAN></B> Geographic =
Systems=20
LLC; shrug-L@lists.dep.state.fl.us<BR><B><SPAN=20
style=3D"FONT-WEIGHT: bold">Subject:</SPAN></B> RE: shrug-l: Question =
du=20
jour</SPAN></FONT><o:p></o:p></P></DIV>
<P class=3DMsoNormal><FONT face=3D"Times New Roman" size=3D3><SPAN=20
style=3D"FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dblue size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; COLOR: blue; FONT-FAMILY: Arial">That's a =
good=20
website. From it I gather that if I want BOTH the distances and =
azimuths=20
to my sampling locations from the site center to be the most accurate, =
the=20
Azimuthal Equidistant projection is the best=20
solution.</SPAN></FONT><o:p></o:p></P>
<P class=3DMsoNormal><FONT face=3D"Times New Roman" size=3D3><SPAN=20
style=3D"FONT-SIZE: 12pt"> <o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dblue size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; COLOR: blue; FONT-FAMILY: Arial">I came up =
with part=20
of the rest of your solution on my own, however, I'm having trouble =
rotating=20
it through 360=B0.</SPAN></FONT><o:p></o:p></P>
<P class=3DMsoNormal><FONT face=3D"Times New Roman" size=3D3><SPAN=20
style=3D"FONT-SIZE: 12pt"> <o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dblue size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; COLOR: blue; FONT-FAMILY: Arial">Another =
solution I=20
thought of, is setting up the sector lines in an AutoCad file, then =
importing=20
it into my map with a world file using the center point and the =
intersection=20
of the first radial with the 10 mile buffer ring as the two=20
points.</SPAN></FONT><o:p></o:p></P>
<P><B><FONT face=3D"Monotype Corsiva" size=3D5><SPAN=20
style=3D"FONT-WEIGHT: bold; FONT-SIZE: 18pt; FONT-FAMILY: 'Monotype =
Corsiva'">--=20
John</SPAN></FONT></B> <o:p></o:p></P>
<DIV>
<P class=3DMsoNormal><FONT face=3D"Times New Roman" size=3D3><SPAN=20
style=3D"FONT-SIZE: 12pt"> <o:p></o:p></SPAN></FONT></P></DIV>
<P class=3DMsoNormal><FONT face=3D"Times New Roman" size=3D3><SPAN=20
style=3D"FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P>
<DIV class=3DMsoNormal style=3D"TEXT-ALIGN: center" =
align=3Dcenter><FONT=20
face=3D"Times New Roman" size=3D3><SPAN style=3D"FONT-SIZE: 12pt">
<HR tabIndex=3D-1 align=3Dcenter width=3D"100%" SIZE=3D2>
</SPAN></FONT></DIV>
<P class=3DMsoNormal style=3D"MARGIN-BOTTOM: 12pt"><B><FONT =
face=3DTahoma=20
size=3D2><SPAN=20
style=3D"FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: =
Tahoma">From:</SPAN></FONT></B><FONT=20
face=3DTahoma size=3D2><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Tahoma">=20
Geographic Systems LLC [mailto:info@geographicsystems.com] =
<BR><B><SPAN=20
style=3D"FONT-WEIGHT: bold">Sent:</SPAN></B> Friday, September 30, =
2005 12:19=20
PM<BR><B><SPAN style=3D"FONT-WEIGHT: bold">To:</SPAN></B> Sykes,=20
John<BR><B><SPAN style=3D"FONT-WEIGHT: bold">Subject:</SPAN></B> RE: =
shrug-l:=20
Question du jour</SPAN></FONT><o:p></o:p></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Hi=20
John,<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">I will try =
to address=20
the first part of your question (drawing lines out 10 miles at 11.25 =
degree=20
increments) and the last part (projections). The second part of =
your=20
question (rhumb line from site point to sampling location) may require =
more=20
research.<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Projections =
=96=20
definitely play a part in spatial accuarcy. My guess is you want =
a=20
projection that preserves direction and distance. A good place =
to start=20
is the summary tables at the bottom of the map projection poster, <A=20
=
href=3D"http://erg.usgs.gov/isb/pubs/MapProjections/projections.html">htt=
p://erg.usgs.gov/isb/pubs/MapProjections/projections.html</A>.=20
<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Drawing =
lines of=20
specific distance and angle. You can do this manually when you =
sketch a=20
line. With Task set to Create New Feature and Target your line =
feature=20
class, click the sketch tool (pencil) and click on the first point of =
your=20
line. Then right click away from the sketch and select =
=93Direction=94 (or=20
CTRL-A) specify an angle (0 being horizontal =96 ie =9311.25=94) and =
then right=20
click away from sketch again and select =93Length=94 (or CTRL-L) ie =
=932mi=94 (=93mi=94=20
for miles). Or you can enter both the first time you right click =
by=20
selecting =93Direction/Length=94 (or CTRL-G). Check out online =
help for=20
=93Creating segments using angles and =
lengths=94.<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<DIV>
<DIV>
<P class=3DMsoNormal><EM><I><FONT face=3DArial color=3Dnavy =
size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Miguel=20
Garriga</SPAN></FONT></I></EM><FONT color=3Dnavy><SPAN=20
style=3D"COLOR: navy"><o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Geographic =
Systems,=20
LLC</SPAN></FONT><FONT color=3Dnavy><SPAN=20
style=3D"COLOR: navy"><o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><A=20
=
href=3D"http://www.geographicsystems.com">www.geographicsystems.com</A></=
SPAN></FONT><FONT=20
color=3Dnavy><SPAN style=3D"COLOR: navy"><o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: =
Arial">407-261-0451</SPAN></FONT><FONT=20
color=3Dnavy><SPAN style=3D"COLOR: navy"><o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial color=3Dnavy size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">cel=20
321-279-6019</SPAN></FONT><o:p></o:p></P></DIV></DIV>
<DIV>
<DIV class=3DMsoNormal style=3D"TEXT-ALIGN: center" =
align=3Dcenter><FONT=20
face=3D"Times New Roman" size=3D3><SPAN style=3D"FONT-SIZE: 12pt">
<HR tabIndex=3D-1 align=3Dcenter width=3D"100%" SIZE=3D2>
</SPAN></FONT></DIV>
<P class=3DMsoNormal><B><FONT face=3DTahoma size=3D2><SPAN=20
style=3D"FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: =
Tahoma">From:</SPAN></FONT></B><FONT=20
face=3DTahoma size=3D2><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Tahoma">=20
shrug-l-admin@lists.dep.state.fl.us=20
[mailto:shrug-l-admin@lists.dep.state.fl.us] <B><SPAN=20
style=3D"FONT-WEIGHT: bold">On Behalf Of </SPAN></B>Sykes, =
John<BR><B><SPAN=20
style=3D"FONT-WEIGHT: bold">Sent:</SPAN></B> Friday, September 30, =
2005 10:21=20
AM<BR><B><SPAN style=3D"FONT-WEIGHT: bold">To:</SPAN></B>=20
shrug-L@lists.dep.state.fl.us<BR><B><SPAN=20
style=3D"FONT-WEIGHT: bold">Subject:</SPAN></B> shrug-l: Question du=20
jour</SPAN></FONT><o:p></o:p></P></DIV>
<P class=3DMsoNormal><FONT face=3D"Times New Roman" size=3D3><SPAN=20
style=3D"FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P>
<P><FONT face=3DArial size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; FONT-FAMILY: Arial">Since we =
(collectively) solved=20
the question I had yesterday, here's a new one (put on your thinking =
caps -=20
this one's tougher!).</SPAN></FONT><o:p></o:p></P>
<P><FONT face=3DArial size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; FONT-FAMILY: Arial">Problem</SPAN></FONT>=20
<o:p></o:p></P>
<P><FONT face=3DArial size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; FONT-FAMILY: Arial">When establishing =
environmental=20
sampling locations around a site, we like to ensure that the various =
distance=20
buffer rings are evenly covered (e.g., in this case: "site =
boundary" to=20
2 miles, 2 - 5 miles and 5 - 10 miles. This is simple to create =
and=20
check with the standard multiple buffer tool in=20
ArcToolbox.</SPAN></FONT><o:p></o:p></P>
<P><FONT face=3DArial size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; FONT-FAMILY: Arial">However, we also like =
to check=20
that the 16 compass sectors around the site have also been evenly=20
covered*. These 22-1/2=B0 sectors are centered on N, NNE, NE, =
ENE, E, ESE,=20
SE, SSE, S, SSW, SW, WSW, W, WNW, NW and =
NNW.</SPAN></FONT><o:p></o:p></P>
<P><FONT face=3DArial size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; FONT-FAMILY: Arial">So, what I would like =
to do is=20
to create these sectors visually, by drawing a line from the origin =
(an=20
arbitrary "center" point on the site) out to 10 miles starting at =
11-1/4=B0=20
compass heading, then rotate around 22-1/2=B0 and draw a line, until =
the 16=20
sectors are visually defined.</SPAN></FONT><o:p></o:p></P>
<P><FONT face=3DArial size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; FONT-FAMILY: Arial">Any suggestions as how =
this can=20
be done (easily)? Previously, when doing this in AutoCad, I used =
a=20
radial copy command. I haven't noticed a similar command in=20
ArcGIS.</SPAN></FONT><o:p></o:p></P>
<P><FONT face=3DArial size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; FONT-FAMILY: Arial">Finally, once the =
sampling=20
location is selected (and the lat/long of that location determined), =
we need=20
to be able to determine and list the distance and azimuth (rhumb line) =
from=20
that arbitrary "center" point on the site to the sampling location and =
put it=20
into the sampling location attributes table (in the past, I've done =
this using=20
the NGS "Inverse" program [fudging the rhumb line from the great =
circle=20
azimuths] using a batch file input/output) for atmospheric dispersion=20
modeling. However, I don't see any easy way to do this with =
ArcInfo=20
(especially on a batch file basis). Any=20
suggestions?</SPAN></FONT><o:p></o:p></P>
<P><FONT face=3DArial size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; FONT-FAMILY: Arial">Finally, food for =
thought -- How=20
does the projection being used effect the accuracy of all of =
this? =20
Normally we use Albers (equal area) or Mercator (which gives the most =
accurate=20
rhumb lines), but is there a better projection to use to obtain =
accurate=20
distances & azimuths? I understand from the reading I've =
done that=20
these functions may be rather=20
projection-sensitive.</SPAN></FONT><o:p></o:p></P>
<P><B><FONT face=3D"Monotype Corsiva" size=3D5><SPAN=20
style=3D"FONT-WEIGHT: bold; FONT-SIZE: 18pt; FONT-FAMILY: 'Monotype =
Corsiva'">--=20
John</SPAN></FONT></B> <o:p></o:p></P>
<P><FONT face=3DArial size=3D4><SPAN=20
style=3D"FONT-SIZE: 13.5pt; FONT-FAMILY: Arial">*Sometimes if there is =
a=20
prevailing wind bias, we'll bias our sampling locations to that =
prevailing=20
wind direction, but in the current case there is no strong prevailing =
wind=20
direction - the annual wind rose shows an almost random=20
=
360=B0pattern.</SPAN></FONT><o:p></o:p></P></DIV></BLOCKQUOTE></BODY></HT=
ML>
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