<html><head></head><body><div style="color:#000; background-color:#fff; font-family:verdana, helvetica, sans-serif;font-size:13px"><div id="yui_3_16_0_ym19_1_1478721586313_55884">Hi Martin,</div><div id="yui_3_16_0_ym19_1_1478721586313_55883"><br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1478721586313_55924">I've actually add a look at this <b>user_data</b> field but have a single value of '2' for all my points when reading with libLAS while the HEIGHT_ABOVE_GROUND attribute showing in GlobalMapper is ranging from -0.002 to 33.909.</div><div dir="ltr" id="yui_3_16_0_ym19_1_1478721586313_55801"><br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1478721586313_55881">Cheers,<br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1478721586313_55880">Alex</div><div dir="ltr" id="yui_3_16_0_ym19_1_1478721586313_55879"><br></div><div id="yui_3_16_0_ym19_1_1478721586313_55637"><span></span></div><div id="yui_3_16_0_ym19_1_1478721586313_55593"> </div><div class="signature" id="yui_3_16_0_ym19_1_1478721586313_55592"><div id="yui_3_16_0_ym19_1_1478721586313_55591"> </div></div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1478721586313_55383"><br><br></div><div class="yahoo_quoted" id="yui_3_16_0_ym19_1_1478721586313_55689" style="display: block;"> <div style="font-family: verdana, helvetica, sans-serif; font-size: 13px;" id="yui_3_16_0_ym19_1_1478721586313_55688"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_ym19_1_1478721586313_55687"> <div dir="ltr" id="yui_3_16_0_ym19_1_1478721586313_55889"> <font id="yui_3_16_0_ym19_1_1478721586313_55888" size="2" face="Arial"> <hr size="1"> <b><span style="font-weight:bold;">De :</span></b> Martin Isenburg <martin.isenburg@gmail.com><br> <b><span style="font-weight: bold;">À :</span></b> Alexandre Guyot <alexguyot@yahoo.fr> <br><b><span style="font-weight: bold;">Cc :</span></b> Howard Butler <howard@hobu.co>; "Van Dyke, Daryl" <daryl_van_dyke@fws.gov>; "Liblas-devel@lists.osgeo.org" <liblas-devel@lists.osgeo.org><br> <b><span style="font-weight: bold;">Envoyé le :</span></b> Mercredi 9 novembre 2016 22h30<br> <b><span style="font-weight: bold;">Objet :</span></b> Re: [Liblas-devel] Liblas-devel Digest, Vol 79, Issue 1<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_ym19_1_1478721586313_55686"><br><div id="yiv2494137207"><div id="yui_3_16_0_ym19_1_1478721586313_55902"><div dir="ltr" id="yui_3_16_0_ym19_1_1478721586313_55901">Hi,<div><br clear="none"></div><div>in this case you are indeed just be storing HAG as a quantized value in decimeters (or decifeet) in the 8 bit unsigned user_data field that ranges from 0 to 255 (e.g. 0 to 25.5 meters or feet). See the README file of lasheight for details.</div><div><br clear="none"></div><div><a rel="nofollow" shape="rect" target="_blank" href="http://lastools.org/download/lasheight_README.txt" style="font-size:12.8px;">http://lastools.org/download/ lasheight_README.txt</a><br clear="none"></div><div><br clear="none"></div><div>Furthermore you seem then to merely visualize the user_data field in Global Mapper and not a dedicated HAG field.</div><div><br clear="none"></div><div>Regards,</div><div><br clear="none"></div><div>Martin</div></div><div class="yiv2494137207yqt9436213276" id="yiv2494137207yqt80125"><div class="yiv2494137207gmail_extra"><br clear="none"><div class="yiv2494137207gmail_quote">On Wed, Nov 9, 2016 at 9:55 PM, Alexandre Guyot <span dir="ltr"><<a rel="nofollow" shape="rect" ymailto="mailto:alexguyot@yahoo.fr" target="_blank" href="mailto:alexguyot@yahoo.fr">alexguyot@yahoo.fr</a>></span> wrote:<br clear="none"><blockquote class="yiv2494137207gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div><div style="color:#000;background-color:#fff;font-family:verdana, helvetica, sans-serif;font-size:13px;"><div id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20065">Hi,</div><div id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20066"><br clear="none"></div><div id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20067">Thanks for your help.</div><div id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20062"><div dir="ltr" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20072"><span id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20063">Actually, I havent' specified any switch in lasheight.</span><span id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20064"><br clear="none"></span></div><div dir="ltr" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_21379"><span id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20064"><br clear="none"></span></div><div dir="ltr" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20089"><span id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20928">My file is in LAS 1.2 and effectively has the HAG value as i</span><span id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20929">t can be read by some commercial software such as GlobalMapper (as "HEIGHT_ABOVE_GROUND" attribute).</span></div><div dir="ltr" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_21376"><span id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20929"><br clear="none"></span></div><div id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_21112">Is it therefore stored somewhere else than in extra-bytes or was LAS 1.2 already using extra-bytes ?</div><div dir="ltr" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20891"><span id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20064"><br clear="none"></span></div><div dir="ltr" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20892"><span id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20064">Thanks,</span></div><div dir="ltr" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20907"><span id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20064">Alex<br clear="none"></span></div></div><div id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20068"><span></span></div><div id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20069"> </div><div class="yiv2494137207m_-1968350248442450237signature" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20071"><div id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20070"> </div></div><div class="yiv2494137207m_-1968350248442450237qtdSeparateBR" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20093"><br clear="none"><br clear="none"></div><div class="yiv2494137207m_-1968350248442450237yahoo_quoted" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20097" style="display:block;"> <div id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20096" style="font-family:verdana, helvetica, sans-serif;font-size:13px;"> <div id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20095" style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"> <div dir="ltr" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20094"> <font id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20098" size="2" face="Arial"> </font><hr id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20152" size="1"> <b id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_21416"><span id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_21415" style="font-weight:bold;">De :</span></b> Howard Butler <<a rel="nofollow" shape="rect" ymailto="mailto:howard@hobu.co" target="_blank" href="mailto:howard@hobu.co">howard@hobu.co</a>><br clear="none"> <b><span style="font-weight:bold;">À :</span></b> Martin Isenburg <<a rel="nofollow" shape="rect" ymailto="mailto:martin.isenburg@gmail.com" target="_blank" href="mailto:martin.isenburg@gmail.com">martin.isenburg@gmail.com</a>> <br clear="none"><b><span style="font-weight:bold;">Cc :</span></b> "Van Dyke, Daryl" <<a rel="nofollow" shape="rect" ymailto="mailto:daryl_van_dyke@fws.gov" target="_blank" href="mailto:daryl_van_dyke@fws.gov">daryl_van_dyke@fws.gov</a>>; "<a rel="nofollow" shape="rect" ymailto="mailto:Liblas-devel@lists.osgeo.org" target="_blank" href="mailto:Liblas-devel@lists.osgeo.org">Liblas-devel@lists.osgeo.org</a>" <<a rel="nofollow" shape="rect" ymailto="mailto:liblas-devel@lists.osgeo.org" target="_blank" href="mailto:liblas-devel@lists.osgeo.org">liblas-devel@lists.osgeo.org</a>><br clear="none"> <b><span style="font-weight:bold;">Envoyé le :</span></b> Mercredi 9 novembre 2016 21h29<br clear="none"> <b><span style="font-weight:bold;">Objet :</span></b> Re: [Liblas-devel] Liblas-devel Digest, Vol 79, Issue 1<br clear="none"> </div> <div class="yiv2494137207m_-1968350248442450237y_msg_container" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20099"><div><div class="yiv2494137207h5"><br clear="none"><br clear="none">> On Nov 9, 2016, at 2:20 PM, Martin Isenburg <<a rel="nofollow" shape="rect" ymailto="mailto:martin.isenburg@gmail.com" target="_blank" href="mailto:martin.isenburg@gmail.com">martin.isenburg@gmail.com</a>> wrote:<br clear="none">> <br clear="none">> Hi,<br clear="none">> <br clear="none">> I believe that Alex talks about the HAG stored as an additional point atttribute to an "Extra Bytes" field via the '-store_as_extra_bytes' switch.<br clear="none">> <br clear="none">> <a rel="nofollow" shape="rect" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20867" target="_blank" href="http://lastools.org/download/lasheight_README.txt">http://lastools.org/download/ lasheight_README.txt</a><br clear="none">> <br clear="none">> There was a discussion on this in the LAStools user forum whether cm resolution with a scale factor of 0.01 and a 16 bits signed integer storage are enough for most trees.<br clear="none">> <br clear="none">> <a rel="nofollow" shape="rect" id="yiv2494137207m_-1968350248442450237yui_3_16_0_ym19_1_1478721586313_20870" target="_blank" href="http://groups.google.com/forum/#!searchin/lastools/lasheight$20store_as_extra_bytes">http://groups.google.com/ forum/#!searchin/lastools/ lasheight$20store_as_extra_ bytes</a><br clear="none">> <br clear="none">> "Extra Bytes" fields are described in the LAS 1.4 specification and are therefore also more and more readable in other software.<br clear="none"><br clear="none">All of this is accurate information.<br clear="none"><br clear="none">Additionally, libLAS does not support LAS 1.4 or support writing LAS 1.4 extra bytes descriptor VLRs. You'll need to use LAStools or PDAL or LASpy to achieve this task if open source is a priority for you.<br clear="none"><br clear="none">Howard</div></div><div class="yiv2494137207m_-1968350248442450237yqt8402420912" id="yiv2494137207m_-1968350248442450237yqtfd94807"><br clear="none"><span class="yiv2494137207">______________________________ _________________<br clear="none">Liblas-devel mailing list<br clear="none"><a rel="nofollow" shape="rect" ymailto="mailto:Liblas-devel@lists.osgeo.org" target="_blank" href="mailto:Liblas-devel@lists.osgeo.org">Liblas-devel@lists.osgeo.org</a><br clear="none"><a rel="nofollow" shape="rect" target="_blank" href="http://lists.osgeo.org/mailman/listinfo/liblas-devel">http://lists.osgeo.org/ mailman/listinfo/liblas-devel</a></span></div><br clear="none"><br clear="none"></div> </div> </div> </div></div></div></blockquote></div><br clear="none"></div></div></div></div><br><br></div> </div> </div> </div></div></body></html>