[gdal-dev] Fwd: How to add labels to DEM contour lines

[Kirk Waters - NOAA Federal]

KC,
I looked into this a few years ago, so things may have changed. A write-up
of what I did with both kmz and pdf is at
https://geozoneblog.wordpress.com/2021/12/09/dav-new-products/ with the
details toward the bottom. It might be that you'd need to add a layer to
the kmz with a point and label where you want them.

Kirk Waters, PhD
NOAA Office for Coastal Management
Applied Sciences Program
coast.noaa.gov/digitalcoast




On Thu, Jul 18, 2024 at 11:50 AM Open Land LLC via gdal-dev <
gdal-dev at lists.osgeo.org> wrote:

> Hi Everyone,
>
> I just wanted to ask - Is this the right place to post questions? I put in
> a post several days ago, and just want to make sure I'm putting it in the
> right place, because I have not posted to this group before. Thank you - KC
>
> ---------- Forwarded message ---------
> From: Open Land LLC <realoption11 at gmail.com>
> Date: Mon, Jul 15, 2024 at 9:00 PM
> Subject: How to add labels to DEM contour lines
> To: <gdal-dev at lists.osgeo.org>
>
>
> Hi everyone, this is my first post. I've also posted this to
> https://stackoverflow.com/questions/78751101/labelling-contour-lines-with-ogr-style
>
> I'm trying to add labels to DEM contour lines.
>
> I'm working with GDAL 3.6.2. , which I installed using Anaconda . I have
> some DEM data from USGS which I wrote as a contour map to a KML file using:
>
>     gdal_contour small.tif /home/ubuntu/node/geotools/contour.kml -i 3.0
> -f KML -a ELEVATION
>
> When I open contour.kml in vim, I can see that its made up of features
> like:
>
> <Placemark>
>
> <Style><LineStyle><color>ff0000ff</color></LineStyle><PolyStyle><fill>0</fill></PolyStyle></Style>
> <ExtendedData><SchemaData schemaUrl="#contour">
> <SimpleData name="ID">39</SimpleData>
> <SimpleData name="ELEVATION">525</SimpleData>
> </SchemaData></ExtendedData>
> <LineString><coordinates>-89.2626638689733,46.1525006611575
> -89.262663868958,46.1525469572921 -89.2627325352002,46.152622208059
> -89.2628251277396,46.1526266807347 -89.2629177202847,46.1526141000471
> -89.2629982621728,46.1525469573863
> -89.2629982621882,46.1525006612516</coordinates></LineString>
> </Placemark>
>
> Clearly there is a style component available , but I'm not sure how to
> work with it to add elevation labels or custom colours. My suspicion is
> that OGR_STYLE is used to do things like this (
> https://github.com/OSGeo/gdal/issues/835)(https://gdal.org/user/ogr_sql_dialect.html#ogr-style
> ), but I can't find any examples. How can this be done?
>
> Thank you very much,
>
> KC
>
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