<html dir="ltr">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style id="owaParaStyle">P {
MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px
}
</style>
</head>
<body fPStyle="1" ocsi="0">
<div style="direction: ltr;font-family: Times New Roman;color: #000000;font-size: x-small;">
<p>I have not looked at your macro in detail other than to comment that I thought the Michigan RSO used a different value for the semi-major axis of the ellipsoid in order to take into account the average elevation of the State. I see you are using GRS80 exactly,
which may be your problem.</p>
<div>
<p> </p>
<div style="FONT-FAMILY: Tahoma; FONT-SIZE: 13px">
<p><font face="Copperplate Gothic Bold">Clifford J. Mugnier, c.p., c.m.s.</font></p>
<p><font face="Copperplate Gothic Bold">Chief of Geodesy</font></p>
<p><font face="Copperplate Gothic Bold">LSU Center for GeoInformatics (ERAD 266)</font></p>
<p><font face="Copperplate Gothic Bold">Dept. of Civil Engineering (P.F. Taylor 3531)</font></p>
<p><font face="Copperplate Gothic Bold">LOUISIANA STATE UNIVERSITY</font></p>
<p><font face="Copperplate Gothic Bold">Baton Rouge, LA 70803</font></p>
<p><font face="Copperplate Gothic Bold">Academic: (225) 578-8536</font></p>
<p><font face="Copperplate Gothic Bold">Research: (225) 578-4578</font></p>
<p><font face="Copperplate Gothic Bold">Cell: (225) 328-8975</font></p>
<p><font face="Copperplate Gothic Bold">honorary lifetime member, lsps</font></p>
<p><font face="Copperplate Gothic Bold">fellow emeritus, asprs</font></p>
<p><font face="Copperplate Gothic Bold">member, apsg</font></p>
</div>
</div>
<div style="FONT-FAMILY: Times New Roman; COLOR: #000000; FONT-SIZE: 16px">
<hr tabindex="-1">
<div style="DIRECTION: ltr" id="divRpF364714"><font color="#000000" size="2" face="Tahoma"><b>From:</b> proj-bounces@lists.maptools.org [proj-bounces@lists.maptools.org] on behalf of Rick Graves [gravesricharde@yahoo.com]<br>
<b>Sent:</b> Sunday, July 22, 2012 11:41 AM<br>
<b>To:</b> proj@lists.maptools.org<br>
<b>Subject:</b> [Proj] does proj.4 work with Hotine Oblique Mercator?<br>
</font><br>
</div>
<div></div>
<div>
<div style="BACKGROUND-COLOR: #fff; FONT-FAMILY: arial,helvetica,sans-serif; COLOR: #000; FONT-SIZE: 12pt">
<div style="FONT-FAMILY: arial,helvetica,sans-serif; FONT-SIZE: 12pt">Hey,</div>
<div style="FONT-FAMILY: arial,helvetica,sans-serif; FONT-SIZE: 12pt"><br>
</div>
<div style="FONT-FAMILY: arial,helvetica,sans-serif; FONT-SIZE: 12pt">I am not sure that proj.4 is converting latitude and longitude into Hotine Oblique Mercator <span style="FONT-SIZE: 12pt">coordinates correctly. (But I am a newbie at cartography and such,
so please bear with me, I could be making a mistake.)</span></div>
<div style="FONT-FAMILY: arial,helvetica,sans-serif; FONT-SIZE: 12pt"><br>
</div>
<div style="FONT-FAMILY: arial,helvetica,sans-serif; FONT-SIZE: 12pt">As a result of the 2010 census in the USA, many states have redrawn their congressional districts. Michigan is one, and the shapefiles for their new districts were created using the Hotine
Oblique Mercator projection to get the whole state onto one map with a minimum of overall distortion. There is a map and explanation here:</div>
<div style="FONT-FAMILY: arial,helvetica,sans-serif; FONT-SIZE: 12pt"><br>
</div>
<div><font face="arial, helvetica, sans-serif">http://www.michigan.gov/documents/DNR_Map_Proj_and_MI_Georef_Info_20889_7.pdf</font><br>
</div>
<div style="FONT-FAMILY: arial,helvetica,sans-serif; FONT-SIZE: 12pt"><br>
</div>
<div style="FONT-FAMILY: arial,helvetica,sans-serif; FONT-SIZE: 12pt">One can download Michigan's new Congressional district shapefiles from here:</div>
<div style="FONT-FAMILY: arial,helvetica,sans-serif; FONT-SIZE: 12pt"><br>
</div>
<div><font face="arial, helvetica, sans-serif">http://www.mcgi.state.mi.us/mgdl/?rel=thext&action=thmname&cid=9&cat=Legislative+Districts+2010+US+Congress</font><br>
</div>
<div><font face="arial, helvetica,
sans-serif"><br>
</font></div>
<div><font face="arial, helvetica, sans-serif">The included prj file has this info:</font></div>
<div><font face="arial, helvetica, sans-serif"><br>
</font></div>
<div><font face="arial, helvetica, sans-serif">
<div>PROJCS["NAD83 / Michigan Oblique Mercator",</div>
<div>GEOGCS["NAD83",</div>
<div> DATUM["North_American_Datum_1983",</div>
<div><span style="WHITE-SPACE: pre" class="Apple-tab-span"></span>SPHEROID["GRS 1980",6378137,298.257222101,</div>
<div><span style="WHITE-SPACE: pre" class="Apple-tab-span"></span> AUTHORITY["EPSG","7019"]],</div>
<div><span style="WHITE-SPACE: pre" class="Apple-tab-span"></span>AUTHORITY["EPSG","6269"]],</div>
<div> PRIMEM["Greenwich",0,</div>
<div><span style="WHITE-SPACE: pre" class="Apple-tab-span"></span>AUTHORITY["EPSG","8901"]],</div>
<div> UNIT["degree",0.01745329251994328,</div>
<div><span style="WHITE-SPACE: pre" class="Apple-tab-span"></span>AUTHORITY["EPSG","9122"]],</div>
<div> AUTHORITY["EPSG","4269"]],</div>
<div>UNIT["metre",1,</div>
<div> AUTHORITY["EPSG","9001"]],</div>
<div>PROJECTION["Hotine_Oblique_Mercator"],</div>
<div>PARAMETER["latitude_of_center",45.30916666666666],</div>
<div>PARAMETER["longitude_of_center",-86],</div>
<div>PARAMETER["azimuth",337.25556],</div>
<div>PARAMETER["rectified_grid_angle",337.25556],</div>
<div>PARAMETER["scale_factor",0.9996],</div>
<div>PARAMETER["false_easting",2546731.496],</div>
<div>PARAMETER["false_northing",-4354009.816],</div>
<div>AUTHORITY["EPSG","3078"],</div>
<div>AXIS["X",EAST],</div>
<div>AXIS["Y",NORTH]]</div>
<div><br>
</div>
<div>This page has info on the <span style="FONT-SIZE: 16px">Hotine Oblique Mercator:</span></div>
<div><span style="FONT-SIZE: 16px"><br>
</span></div>
<div>http://www.remotesensing.org/geotiff/proj_list/hotine_oblique_mercator.html<br>
</div>
<div><br>
</div>
<div>Using that, I came up with this command to invoke proj:</div>
<div><br>
</div>
<div>
<div>proj +proj=omerc +lat_0=45.30916666666666 +lonc=-86 +alpha=337.25556 +k_0=0.9996 +x_0=2546731.496 +y_0=-4354009.816</div>
<div><br>
</div>
<div>I get a latitude and longitude for Ann Arbor Michigan of 42 15 N - 83 45 W here:</div>
<div><br>
</div>
<div>http://wiki.answers.com/Q/What_is_the_latitude_and_longitude_of_ann_arbor_mi<br>
</div>
<div><br>
</div>
<div>Plugging 42d15N 83d45W into proj, I get -7945305.71 17799792.28. But the bounding box of the entire state's shape file is this:</div>
<div><br>
</div>
<div>161318.17712499946, 128066.04250000045, 791832.2827499993, 859206.8181249984<br>
</div>
<div><br>
</div>
<div>The values I get from proj are both out of bounds. </div>
<div><br>
</div>
<div>Am I doing something wrong?</div>
<div><br>
</div>
<div>Thanks,</div>
<div><br>
</div>
<div>Rick Graves</div>
<div><br>
</div>
</div>
</font></div>
</div>
</div>
</div>
</div>
</body>
</html>