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<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US">Quick glance at your DEM and it looks wrong, you can see the points, which to me suggests there’s an issue.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US">As I don’t 100% know the resolution of the original data you are sampling, my advice is limited to a best guess. From what I can see, online, Google elevations are based on Satellite
Radar Topographic Mapping (SRTM) and has a resolution of 30m.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US">You might be better trying to get the original SRTM data from
<a href="https://earthexplorer.usgs.gov/">HERE</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US">Alternatively, try using Pixel size values in the IDW Interpolation, setting it to 30 x and 30 y and see what you get.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US">Kind Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US">Richard.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="mso-ligatures:none">From:</span></b><span lang="EN-US" style="mso-ligatures:none"> QGIS-User <qgis-user-bounces@lists.osgeo.org>
<b>On Behalf Of </b>Greg via QGIS-User<br>
<b>Sent:</b> 23 February 2024 04:13<br>
<b>To:</b> qgis-user@lists.osgeo.org<br>
<b>Subject:</b> [Qgis-user] How to create 3d terrain from DEM?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US">Hello QGIS users,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">We have a piece of land in Grand Lake, CO. We want to build a house on it but the land is on a slope so we need to have a 3D terrain map to locate the house at the optimal location. I’m mainly going off this video
<a href="https://www.youtube.com/watch?v=eZZ2MVLZN4o">https://www.youtube.com/watch?v=eZZ2MVLZN4o</a> but it doesn’t work for me.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I start by making a line string in Google Earth, like this:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-ligatures:none"><img border="0" width="401" height="291" style="width:4.177in;height:3.0312in" id="Picture_x0020_1" src="cid:image006.jpg@01DA663B.609D8310"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Then I save it as .kml file and import that file into
<i>GPS Visualizer</i>. That gets all the elevations along the line. Then I <i>Convert & add elevation</i> as a
<i>plain text</i> file and save the file. <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Then in <i>QGIS version 3.28.14-Firenze</i>, I select
<i>Layer > Add Layer > Add Delimited Text Layer</i>. In the popup window, I open the text file and the data gets imported. The
<i>Sample Data</i> looks good. I select <i>X field as LONG, Y field as LAT, and Z field as ALT</i>. I leave all the other fields at their defaults and click the
<i>Add</i> button. All the points come in as shown:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-ligatures:none"><img border="0" width="401" height="277" style="width:4.177in;height:2.8854in" id="Picture_x0020_2" src="cid:image008.jpg@01DA663B.609D8310"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Next, I create the DEM by double-clicking the
<i>Interpolation</i> > <i>IDW</i> <i>interpolation</i> in the <i>Processing Toolbox</i>. In the popup dialog, I click the plus button to add a layer and set its
<i>Type</i> to <i>Structure lines</i>. I set the <i>Extent</i> to <i>Calculate from Layer >
</i>[name of elevation points]. I set the <i>Rows</i> to 100, leave the rest at their defaults, and click the
<i>Run</i> button. After about 5 seconds it creates a DEM as shown:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-ligatures:none"><img border="0" width="416" height="250" style="width:4.3333in;height:2.6041in" id="Picture_x0020_3" src="cid:image010.jpg@01DA663B.609D8310"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Next, I select <i>Basemaps > Google Satellite</i> from the
<i>HCMGIS</i> plugin, It loads the image, overlayed on the DEM correctly:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-ligatures:none"><img border="0" width="415" height="272" style="width:4.3229in;height:2.8333in" id="Picture_x0020_4" src="cid:image012.jpg@01DA663B.609D8310"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Finally, I click the green tent icon in the in the
<i>Qgis2threejs Exporter</i> plugin.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Instead of a nice 3D terrain as shown in the video, I get a wonky image like this:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-ligatures:none"><img border="0" width="414" height="225" style="width:4.3125in;height:2.3437in" id="Picture_x0020_5" src="cid:image014.jpg@01DA663B.609D8310"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I’ve spent a month trying to create a 3D terrain model, without success. Can anybody tell me what I’m doing wrong, or recommend a workflow that actually works? Please, no methods that require commercial software such
as ArcMap, Rhino, Civil 3D, Autocad, etc.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thank you!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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