[Qgis-user] USGS 3DEM question: export to kml/kmz

John W. Blue john.blue at rrcic.com
Thu Nov 14 10:01:26 PST 2024


Bernie,

Thank you for the suggestion.

As I was checking out the plugins I did see "Quick Maps" and thought of the same workflow but have not tried it yet.  My only hesitation at the time was wanting to be able to mark the old roadbed as trail.  With some more google searching today I found:

https://ultrajourneys.org/digitizing-trails-in-qgis/

Have not attempted to follow the tutorial so if you know of a better one all ears.  Marking an old roadbed as a trail and getting that trail into a GPX format is the ultimate goal here.

Thanks!

John
 

From: Bernie Connors [mailto:bernie.connors at unb.ca] 
Sent: Wednesday, November 13, 2024 9:03 PM
To: John W. Blue
Cc: qgis-user at lists.osgeo.org
Subject: Re: [Qgis-user] USGS 3DEM question: export to kml/kmz

Here is a suggestion. Keep the USGS DEM tif in QGIS and symbolize it as a hillshade.  It will be very easy to spot abandoned railways in the hillshade.  Then use the Quick Maps plugin to add the Google Satellite map to QGIS.  You can easily switch back and forth between Google Satellite layer and the USGS DEM hillshade.

Cheers,
Bernie.
On Wed, Nov 13, 2024, 10:11 p.m. John W. Blue via QGIS-User <qgis-user at lists.osgeo.org> wrote:
Thanks for the file composition info.

Using that I was able to convert the downloaded 3DEM .tif from a raster to vector using Raster > Conversion > Polygonize (Raster to Vector) option.  The resultant exported .kml file size was almost 1 Gb and while Google earth was to load it, it was nothing but a white square.

I did find that Raster > Analysis > Hillshade was able to produce some remarkable and useable results.  What is strange is that the conversion of the hillshade raster to vector .kml never completes.  It quickly gets to 7% and then seemly stalls out.

Am I not waiting long enough?

John



From: oisin.kelly.wild at gmail.com [mailto:oisin.kelly.wild at gmail.com] 
Sent: Tuesday, November 12, 2024 3:01 PM
To: John W. Blue
Cc: qgis-user at lists.osgeo.org
Subject: Re: [Qgis-user] USGS 3DEM question: export to kml/kmz

The tif file is a raster. 
Kml is a vector format.
You need to use one of the processing tools to extract contours or spot heights and then export the results to kml.
Get BlueMail for Android 
On 12 Nov 2024, at 20:06, "John W. Blue via QGIS-User" <qgis-user at lists.osgeo.org> wrote:
Hello,
 
QGIS newbie here.  I want to use USGS LiDAR to search for abandoned railroad grades as a layer in Google Earth.
 
I am able to download the 1 meter tif from USGS and I am able to add it as a layer in QGIS.  I cannot, however, figure out how export the layer as a kml/kmz file.
 
I right-click on the layer and choose “Export” and then “Save As” followed by dropping the “Format” menu down.  Heaps and heaps of options to choose from but none for kml/kmz.
 
Any help in what I am missing or doing wrong would be appreciated.
 
John 
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