shrug-l: Question du jour
lance.peterson@dot.state.fl.us
lance.peterson@dot.state.fl.us
Fri, 30 Sep 2005 13:21:13 -0400
This is a multipart message in MIME format.
--=_alternative 005F4BDA8525708C_=
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: quoted-printable
I like the back and forth also. This is really the best GIS newsgroup I=20
belong too.
At least we don't have a problem with spam.
Lance Peterson
"Nonie Castro" <nonie=5Fcastro@coxtarget.com>=20
Sent by: shrug-l-admin@lists.dep.state.fl.us
09/30/2005 01:17 PM
To
<shrug-L@lists.dep.state.fl.us>
cc
Subject
RE: shrug-l: Question du jour
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=20
[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
I would like to suggest some sort of protocol that folks post their=20
question, once, then those that have a possible solution contact the=20
person directly not numerous e-mails to the entire user list. After a=20
solution has been decided, the original person posting the question could=20
sum the solutions in one e-mail back to the board. Sorry but my e-mail=20
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
From: shrug-l-admin@lists.dep.state.fl.us=20
[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=20
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=20
having trouble rotating it through 360=B0.
=20
Another solution I thought of, is setting up the sector lines in an=20
AutoCad file, then importing it into my map with a world file using the=20
center point and the intersection of the first radial with the 10 mile=20
buffer ring as the two points.
-- John=20
=20
=20
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=20
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=20
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=20
start is the summary tables at the bottom of the map projection poster,=20
http://erg.usgs.gov/isb/pubs/MapProjections/projections.html.=20
=20
Drawing lines of specific distance and angle. You can do this manually=20
when you sketch a line. With Task set to Create New Feature and Target=20
your line feature class, click the sketch tool (pencil) and click on the=20
first point of your line. Then right click away from the sketch and=20
select ?Direction? (or CTRL-A) specify an angle (0 being horizontal ? ie=20
?11.25?) and then right click away from sketch again and select ?Length?=20
(or CTRL-L) ie ?2mi? (?mi? for miles). Or you can enter both the first=20
time you right click by selecting ?Direction/Length? (or CTRL-G). Check=20
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
From: shrug-l-admin@lists.dep.state.fl.us=20
[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=20
one (put on your thinking caps - this one's tougher!).
Problem=20
When establishing environmental sampling locations around a site, we like=20
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.=20
This is simple to create and check with the standard multiple buffer tool=20
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,=
=20
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=20
drawing a line from the origin (an arbitrary "center" point on the site)=20
out to 10 miles starting at 11-1/4=B0 compass heading, then rotate around=20
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=20
this in AutoCad, I used a radial copy command. I haven't noticed a=20
similar command in ArcGIS.
Finally, once the sampling location is selected (and the lat/long of that=20
location determined), we need to be able to determine and list the=20
distance and azimuth (rhumb line) from that arbitrary "center" point on=20
the site to the sampling location and put it into the sampling location=20
attributes table (in the past, I've done this using the NGS "Inverse"=20
program [fudging the rhumb line from the great circle azimuths] using a=20
batch file input/output) for atmospheric dispersion modeling. However, I=20
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=20
(which gives the most accurate rhumb lines), but is there a better=20
projection to use to obtain accurate distances & azimuths? I understand=20
from the reading I've done that these functions may be rather=20
projection-sensitive.
-- John=20
*Sometimes if there is a prevailing wind bias, we'll bias our sampling=20
locations to that prevailing wind direction, but in the current case there =
is no strong prevailing wind direction - the annual wind rose shows an=20
almost random 360=B0pattern.
--=_alternative 005F4BDA8525708C_=
Content-Type: text/html; charset="ISO-8859-1"
Content-Transfer-Encoding: quoted-printable
<br><font size=3D2 face=3D"sans-serif">I like the back and forth also. This
is really the best GIS newsgroup I belong too.</font>
<br>
<br><font size=3D2 face=3D"sans-serif">At least we don't have a problem with
spam.</font>
<br><font size=3D2 face=3D"sans-serif"><br>
Lance Peterson<br>
</font>
<br>
<br>
<br>
<table width=3D100%>
<tr valign=3Dtop>
<td width=3D40%><font size=3D1 face=3D"sans-serif"><b>"Nonie Castro&qu=
ot;
<nonie=5Fcastro@coxtarget.com></b> </font>
<br><font size=3D1 face=3D"sans-serif">Sent by: shrug-l-admin@lists.dep.sta=
te.fl.us</font>
<p><font size=3D1 face=3D"sans-serif">09/30/2005 01:17 PM</font>
<td width=3D59%>
<table width=3D100%>
<tr>
<td>
<div align=3Dright><font size=3D1 face=3D"sans-serif">To</font></div>
<td valign=3Dtop><font size=3D1 face=3D"sans-serif"><shrug-L@lists.dep.s=
tate.fl.us></font>
<tr>
<td>
<div align=3Dright><font size=3D1 face=3D"sans-serif">cc</font></div>
<td valign=3Dtop>
<tr>
<td>
<div align=3Dright><font size=3D1 face=3D"sans-serif">Subject</font></div>
<td valign=3Dtop><font size=3D1 face=3D"sans-serif">RE: shrug-l: Question du
jour</font></table>
<br>
<table>
<tr valign=3Dtop>
<td>
<td></table>
<br></table>
<br>
<br>
<br><font size=3D2 face=3D"Trebuchet MS">If we are taking a vote - I don't
mind the back and forth in real time. </font>
<br>
<br>
<hr><font size=3D2 face=3D"Tahoma"><b>From:</b> shrug-l-admin@lists.dep.sta=
te.fl.us
[mailto:shrug-l-admin@lists.dep.state.fl.us] <b>On Behalf Of </b>Joe Noble<=
b><br>
Sent:</b> Friday, September 30, 2005 1:06 PM<b><br>
To:</b> Sykes, John; Geographic Systems LLC; shrug-L@lists.dep.state.fl.us<=
b><br>
Subject:</b> RE: shrug-l: Question du jour</font><font size=3D3><br>
</font>
<br><font size=3D2 color=3D#000080 face=3D"Arial">I would like to suggest s=
ome
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 origi=
nal
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</font>
<br><font size=3D2 color=3D#000080 face=3D"Arial"> </font>
<br><font size=3D3 color=3D#000080 face=3D"Times New Roman">Joe Noble </fon=
t>
<br><font size=3D3 color=3D#000080 face=3D"Times New Roman">GIS/IS Coordina=
tor
</font>
<br><font size=3D3 color=3D#000080 face=3D"Times New Roman">Tall Timbers Re=
search
Station</font>
<br><font size=3D3 color=3D#000080 face=3D"Times New Roman">850-893-4153 &n=
bsp;x-232</font>
<br><font size=3D2 color=3D#000080 face=3D"Arial"> </font>
<div align=3Dcenter>
<br>
<hr></div>
<br><font size=3D2 face=3D"Tahoma"><b>From:</b> shrug-l-admin@lists.dep.sta=
te.fl.us
[mailto:shrug-l-admin@lists.dep.state.fl.us] <b>On Behalf Of </b>Sykes,
John<b><br>
Sent:</b> Friday, September 30, 2005 12:41 PM<b><br>
To:</b> Geographic Systems LLC; shrug-L@lists.dep.state.fl.us<b><br>
Subject:</b> RE: shrug-l: Question du jour</font>
<br><font size=3D3 face=3D"Times New Roman"> </font>
<br><font size=3D4 color=3Dblue face=3D"Arial">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 Equid=
istant
projection is the best solution.</font>
<br><font size=3D3 face=3D"Times New Roman"> </font>
<br><font size=3D4 color=3Dblue face=3D"Arial">I came up with part of the r=
est
of your solution on my own, however, I'm having trouble rotating it through
360=B0.</font>
<br><font size=3D3 face=3D"Times New Roman"> </font>
<br><font size=3D4 color=3Dblue face=3D"Arial">Another solution I thought o=
f,
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.</font>
<p><font size=3D5 face=3D"Monotype Corsiva"><b>-- John</b></font><font size=
=3D3 face=3D"Times New Roman">
</font>
<br><font size=3D3 face=3D"Times New Roman"> </font>
<br><font size=3D3 face=3D"Times New Roman"> </font>
<div align=3Dcenter>
<br>
<hr></div>
<br><font size=3D2 face=3D"Tahoma"><b>From:</b> Geographic Systems LLC [mai=
lto:info@geographicsystems.com]
<b><br>
Sent:</b> Friday, September 30, 2005 12:19 PM<b><br>
To:</b> Sykes, John<b><br>
Subject:</b> RE: shrug-l: Question du jour</font>
<br><font size=3D2 color=3D#000080 face=3D"Arial">Hi John,</font>
<br><font size=3D2 color=3D#000080 face=3D"Arial"> </font>
<br><font size=3D2 color=3D#000080 face=3D"Arial">I will try to address the=
first
part of your question (drawing lines out 10 miles at 11.25 degree increment=
s)
and the last part (projections). The second part of your question
(rhumb line from site point to sampling location) may require more research=
.</font>
<br><font size=3D2 color=3D#000080 face=3D"Arial"> </font>
<br><font size=3D2 color=3D#000080 face=3D"Arial">Projections – defin=
itely 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, </font><a href=3Dhttp://=
erg.usgs.gov/isb/pubs/MapProjections/projections.html><font size=3D2 color=
=3Dblue face=3D"Arial"><u>http://erg.usgs.gov/isb/pubs/MapProjections/proje=
ctions.html</u></font></a><font size=3D2 color=3D#000080 face=3D"Arial">.
</font>
<br><font size=3D2 color=3D#000080 face=3D"Arial"> </font>
<br><font size=3D2 color=3D#000080 face=3D"Arial">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. T=
hen
right click away from the sketch and select “Direction” (or CTR=
L-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 on=
line help
for “Creating segments using angles and lengths”.</font>
<br><font size=3D2 color=3D#000080 face=3D"Arial"> </font>
<br><font size=3D2 color=3D#000080 face=3D"Arial"><i>Miguel Garriga</i></fo=
nt>
<br><font size=3D2 color=3D#000080 face=3D"Arial">Geographic Systems, LLC</=
font>
<br><a href=3Dhttp://www.geographicsystems.com/><font size=3D2 color=3Dblue=
face=3D"Arial"><u>www.geographicsystems.com</u></font></a>
<br><font size=3D2 color=3D#000080 face=3D"Arial">407-261-0451</font>
<br><font size=3D2 color=3D#000080 face=3D"Arial">cel 321-279-6019</font>
<div align=3Dcenter>
<br>
<hr></div>
<br><font size=3D2 face=3D"Tahoma"><b>From:</b> shrug-l-admin@lists.dep.sta=
te.fl.us
[mailto:shrug-l-admin@lists.dep.state.fl.us] <b>On Behalf Of </b>Sykes,
John<b><br>
Sent:</b> Friday, September 30, 2005 10:21 AM<b><br>
To:</b> shrug-L@lists.dep.state.fl.us<b><br>
Subject:</b> shrug-l: Question du jour</font>
<br><font size=3D3 face=3D"Times New Roman"> </font>
<p><font size=3D4 face=3D"Arial">Since we (collectively) solved the question
I had yesterday, here's a new one (put on your thinking caps - this one's
tougher!).</font>
<p><font size=3D4 face=3D"Arial">Problem</font><font size=3D3 face=3D"Times=
New Roman">
</font>
<p><font size=3D4 face=3D"Arial">When establishing environmental sampling l=
ocations
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.</font>
<p><font size=3D4 face=3D"Arial">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.</font>
<p><font size=3D4 face=3D"Arial">So, what I would like to do is to create t=
hese
sectors visually, by drawing a line from the origin (an arbitrary "cen=
ter"
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 visu=
ally
defined.</font>
<p><font size=3D4 face=3D"Arial">Any suggestions as how this can be done (e=
asily)?
Previously, when doing this in AutoCad, I used a radial copy command.
I haven't noticed a similar command in ArcGIS.</font>
<p><font size=3D4 face=3D"Arial">Finally, once the sampling location is sel=
ected
(and the lat/long of that location determined), we need to be able to deter=
mine
and list the distance and azimuth (rhumb line) from that arbitrary "ce=
nter"
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?</font>
<p><font size=3D4 face=3D"Arial">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.</font>
<p><font size=3D5 face=3D"Monotype Corsiva"><b>-- John</b></font><font size=
=3D3 face=3D"Times New Roman">
</font>
<p><font size=3D4 face=3D"Arial">*Sometimes if there is a prevailing wind b=
ias,
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.</font>
<p>
--=_alternative 005F4BDA8525708C_=--