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<p>I thought this association is standard. In other words, given the size of one image and type of<span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;"> cylindrical projection, each pixel should be associated to correct (longitude,
latitude) at sphere. My assumption is the image is assumed to unwrap the complete sphere. </span></p>
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<p><font face="Calibri, Arial, Helvetica, sans-serif">Best Regards</font><br>
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<p><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;">Leslie</span></p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> proj-bounces@lists.maptools.org <proj-bounces@lists.maptools.org> on behalf of Jose Gonçalves <jagoncal@gmail.com><br>
<b>Sent:</b> Wednesday, May 25, 2016 11:51 AM<br>
<b>To:</b> PROJ.4 and general Projections Discussions<br>
<b>Subject:</b> Re: [Proj] convert from Equidistant Cylindrical to Eckert I</font>
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<div>An image is georeferenced if there is some form of associating pixel positions (row, column) to geolocation, in geographic or cartographic coordinates.<br>
Proj, or any other program that uses proj, needs that to apply map projection formulas<br>
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In your case you must simulate that your image is georeferenced, giving it an extent of 360 degrees in longitude (row) and some proportional extent in latitude (column).<br>
<div>Regards<br>
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<div>Jose<br>
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<div class="gmail_quote">2016-05-25 0:34 GMT+01:00 Wang Leslie <span dir="ltr"><<a href="mailto:wqyuwss@hotmail.com" target="_blank">wqyuwss@hotmail.com</a>></span>:<br>
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<p>Hi Jose,</p>
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<p>Thanks for the quick reply.</p>
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<p>What do you mean "be geo-referenced"? What I'm thinking is to use these tools to convert a 360 panorama picture, such as <a href="https://upload.wikimedia.org/wikipedia/commons/3/35/Space_Needle_360_Panorama.jpg" title="https://upload.wikimedia.org/wikipedia/commons/3/35/Space_Needle_360_Panorama.jpg
Cmd+Click or tap to follow the link" target="_blank">https://upload.wikimedia.org/wikipedia/commons/3/35/Space_Needle_360_Panorama.jpg</a>,
which is an equidistant cylindrical projection, to other type of projection, which keeps same quality but with smaller size. Thus I can save some storage spaces. In this case, these 360 picture doesn't have any geo-referenced data. Can I still use these tools? </p>
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