<br><br><div class="gmail_quote">On Thu, Aug 23, 2012 at 11:24 AM, Melpati, Muni <span dir="ltr"><<a href="mailto:Muni.Melpati@dot.state.fl.us" target="_blank">Muni.Melpati@dot.state.fl.us</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div lang="EN-US" link="blue" vlink="purple"><div><p>In a shapefile, especially routes, you can have user defined measures (m-values, usually in miles), they might not be same when you measure the two dimenstional line, from start to end vertices of any feature. These shapefiles would have begin and end post fields as attributes.<u></u><u></u></p>
<p>It is not the case for any shapefiles with line types since two dimensional measures deviate from real distance from point a to point b. Moreover they would not be in miles.<u></u><u></u></p><p>I was asking if I import a shapefile of “polyline M” into PostGIS would I be able to get measure in miles given a point or would I be able to get points given a measure in miles? Orelse there is different mechanism in PostGIS</p>
</div></div></blockquote><div><br></div><div>If your shapefile has an M value and you use shp2pgsql to import it into PostGIS, it will still have the M values intact. ogr2ogr and some other tools do not carry forward the M value.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div lang="EN-US" link="blue" vlink="purple"><div><p><u></u><u></u></p><p>to the same job. If so how it is done. I know there are few methods to retrieve a mile point or a measure give a point in PostGIS. Doesn’t this require calibrating the route, first, like I found out in this link (<a href="http://www.faunalia.com/lrs" target="_blank">http://www.faunalia.com/lrs</a>). Sorry for not being very clear in my previous question. I thought people might have confounded this situation and can easily understand it. Please let me know if still do not understand or help me if you can.</p>
</div></div></blockquote><div>You can use all the linear referencing tools on this data using that measure value. See <a href="http://postgis.org/documentation/manual-2.0/reference.html#Linear_Referencing">http://postgis.org/documentation/manual-2.0/reference.html#Linear_Referencing</a></div>
<div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div lang="EN-US" link="blue" vlink="purple"><div><p><u></u><u></u></p><p><u></u> <u></u></p>
<p>Date: Tue, 21 Aug 2012 21:12:04 -0400<u></u><u></u></p><p>From: "Paragon Corporation" <<a href="mailto:lr@pcorp.us" target="_blank">lr@pcorp.us</a>><u></u><u></u></p><p>Subject: Re: [postgis-users] created linear referencing system<u></u><u></u></p>
<p>To: "'PostGIS Users Discussion'"<u></u><u></u></p><p> <<a href="mailto:postgis-users@postgis.refractions.net" target="_blank">postgis-users@postgis.refractions.net</a>><u></u><u></u></p><p>
Message-ID: <527D56A990434161A53D6CA92B3D9ED9@O><u></u><u></u></p><p>Content-Type: text/plain; charset="us-ascii"<u></u><u></u></p><p><u></u> <u></u></p><p>Muni,<u></u><u></u></p><p> <u></u><u></u></p><p>
Not sure what you are asking and maybe others have a similar problem<u></u><u></u></p>
<p>understanding. That might be why you haven't received an answer.<u></u><u></u></p><p> <u></u><u></u></p><p>What do you mean by linear reference capable? All spatial data that is of<u></u><u></u></p><p>linestrings can be linearly referenced. Are you talking about a specific<u></u><u></u></p>
<p>tool you are using?<u></u><u></u></p><p> <u></u><u></u></p><p>when you load your data from shape file to PostGIS, the data is still the<u></u><u></u></p><p>same. If it had linestrings before, it should still have linestrings.<u></u><u></u></p>
<p><u></u> <u></u></p><p> _____ <u></u><u></u></p><p><u></u> <u></u></p><p>From: <a href="mailto:postgis-users-bounces@postgis.refractions.net" target="_blank">postgis-users-bounces@postgis.refractions.net</a><u></u><u></u></p>
<p>[<a href="mailto:postgis-users-bounces@postgis.refractions.net" target="_blank">mailto:postgis-users-bounces@postgis.refractions.net</a>] On Behalf Of Melpati,<u></u><u></u></p><p>Muni<u></u><u></u></p><p>Sent: Tuesday, August 21, 2012 4:07 PM<u></u><u></u></p>
<p>To: <a href="mailto:postgis-users@postgis.refractions.net" target="_blank">postgis-users@postgis.refractions.net</a><u></u><u></u></p><p>Subject: [postgis-users] created linear referencing system<u></u><u></u></p><p><u></u> <u></u></p>
<p><u></u> <u></u></p><p><u></u> <u></u></p><p>Hi,<u></u><u></u></p><p><u></u> <u></u></p><p>I have asked this question before and could not get straight answer. I have<u></u><u></u></p><p>a shape file which Linear reference capable. How to import such data?<u></u><u></u></p>
<p><u></u> <u></u></p><p>If I load the data using shape file loader, would the imported data is<u></u><u></u></p><p>linear reference capable. If not how to recreate linear referencing system<u></u><u></u></p><p>on imported data?<u></u><u></u></p>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br>************************************<br>David William Bitner<br>