<html><head></head><body><div style="color:#000; background-color:#fff; font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_ym19_1_1512806305693_6624"><span id="yui_3_16_0_ym19_1_1512806305693_6698">Hi, from ESRI shapefile specification: </span></div><div id="yui_3_16_0_ym19_1_1512806305693_6624"><span><br></span></div><div id="yui_3_16_0_ym19_1_1512806305693_6624" dir="ltr"><span id="yui_3_16_0_ym19_1_1512806305693_7164"><a href="https://www.esri.com/library/whitepapers/pdfs/shapefile.pdf" id="yui_3_16_0_ym19_1_1512806305693_7163">https://www.esri.com/library/whitepapers/pdfs/shapefile.pdf</a><br></span></div><div id="yui_3_16_0_ym19_1_1512806305693_6624" dir="ltr"><br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_7156">the header file always contains the Mmin and Mmax values (Page 4):<br id="yui_3_16_0_ym19_1_1512806305693_7157"></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_7158"><br id="yui_3_16_0_ym19_1_1512806305693_7159"></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_7160"> "but these limits can contain "no data" values (see Numeric Types on page 2) for shapefiles </div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_7160"> of measured shape types that contain no measures."</div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_7162"><br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_7162">for geometries (Page 15):</div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_7162"> </div><div id="yui_3_16_0_ym19_1_1512806305693_6624" dir="ltr"> "Shape Types in
X,Y,Z Space
Shapes of this type have an optional coordinate M. Note that "no data" </div><div id="yui_3_16_0_ym19_1_1512806305693_6624" dir="ltr"> value can be
specified as a value for M (see Numeric Types on page 2)."</div><div id="yui_3_16_0_ym19_1_1512806305693_6624" dir="ltr"><br></div><div id="yui_3_16_0_ym19_1_1512806305693_6624" dir="ltr"> "PointZ - A PointZ consists of a triplet of double-precision coordinates in the order X, Y, Z plus a
measure."</div><div id="yui_3_16_0_ym19_1_1512806305693_6624" dir="ltr"> ...</div><div id="yui_3_16_0_ym19_1_1512806305693_6624" dir="ltr"><br></div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1512806305693_6629" dir="ltr">the coordinate M is always present, but it can contains a "no data" value to indicate if the geometry is a pure Z-type geometry or a ZM-type geometry.</div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1512806305693_6629" dir="ltr"><br></div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1512806305693_6629" dir="ltr">I think you only can distinguish between both types reading the Mmin and Mmax values of the header file.</div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1512806305693_6629" dir="ltr"><br></div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1512806305693_6629" dir="ltr"><br></div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1512806305693_6629" dir="ltr"><br></div><div class="yahoo_quoted" id="yui_3_16_0_ym19_1_1512806305693_6771" style="display: block;"> <div style="font-family: Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_ym19_1_1512806305693_6770"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_ym19_1_1512806305693_6769"> <div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6768"> <font size="2" face="Arial" id="yui_3_16_0_ym19_1_1512806305693_6894"> <hr size="1" id="yui_3_16_0_ym19_1_1512806305693_6893"> <b id="yui_3_16_0_ym19_1_1512806305693_7580"><span style="font-weight:bold;" id="yui_3_16_0_ym19_1_1512806305693_7579">De:</span></b> Nyall Dawson <nyall.dawson@gmail.com><br> <b><span style="font-weight: bold;">Para:</span></b> gdal dev <gdal-dev@lists.osgeo.org> <br> <b><span style="font-weight: bold;">Enviado:</span></b> Sábado 9 de diciembre de 2017 8:05<br> <b><span style="font-weight: bold;">Asunto:</span></b> [gdal-dev] Shapefiles and z dimensions<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_ym19_1_1512806305693_6971"><br><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6982">Hi all,<br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6972"><br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6981">I'm trying to track down some odd behaviour in QGIS, and determine<br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6980">whether this is a qgis bug, gdal bug, or shapefile limitation.<br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6979"><br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6973">If I create a new shapefile layer using GDALDatasetCreateLayer, with a<br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6978">geometry type of wkbPoint25D (actually any of the 25D) types, then the<br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6977">resultant layer ALWAYS has an M dimension present as well (i.e.<br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6974">ogrinfo reports PointZM type).<br></div><div dir="ltr"><br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6975">Is this expected behaviour for shapefiles?<br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1512806305693_6976"><br></div><div dir="ltr">Nyall<br></div><div dir="ltr">_______________________________________________<br></div><div dir="ltr">gdal-dev mailing list<br></div><div dir="ltr"><a ymailto="mailto:gdal-dev@lists.osgeo.org" href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a><br></div><div dir="ltr"><a href="https://lists.osgeo.org/mailman/listinfo/gdal-dev" target="_blank">https://lists.osgeo.org/mailman/listinfo/gdal-dev</a></div><br><br></div> </div> </div> </div></div><div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br> <table style="border-top: 1px solid #D3D4DE;">
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