[OpenStreetMap talk-lu] Announcing new 10cm imagery and our own hillshade layer in Luxembourg

[Michael Stilmant]

Wow fantastic ! thanks for that work!

On Tue, May 12, 2020 at 9:34 PM Guillaume Rischard <openstreetmap at stereo.lu>
wrote:

> Hi everyone
>
> Maybe you’ve read about the Cadastre’s February 2019 Lidar campaign?
> https://act.public.lu/fr/cartographie/lidar.html. This isn’t the first
> lidar survey in Luxembourg. If you map in the Nordstad, you might have seen
> the high-definition images from the 2017 prototype there.
>
> Usually, pictures are taken around the summer solstice, to reduce the
> length of shadows and have better chances of good weather. This was flown
> in February to get better penetration through trees; and since the plane is
> shooting a laser, shadows aren’t a problem for lidar.
>
> The plane flew over the whole country and shot it with a laser about
> 80 billion times, creating roughly 500 GB of compressed data with the
> details of all the measured points.
>
> At the same time, it made photographs at about 10 cm/pixel. Here’s
> summer 2019 on the right at 20 cm/pixel, February 2019 on the left at
> 10 cm/pixel. The 10 cm imagery is of ‘technical’ quality, not corrected
> for distortions, like rooflines that might not look straight on the
> pictures.
>
>
>
> David Morais Fereira and I then downloaded the whole thing and generated a
> hillshade of it. There was a lot of banging on the data with a keyboard
> until everything worked and rendered properly, lots of failed experiments
> and crashes and bugs and tons of fun.
>
> This isn’t a traditional elevation view: we strip away the trees, but keep
> the buildings. We’re calling it Mapper’s Delight
> <https://www.youtube.com/watch?v=rKTUAESacQM>.
>
> This is cool for forest paths, buildings under trees, cliffs, power lines,
> and mapping the precise position of things without distortions or
> the parallax effects of photo imagery. Buildings are a bit fuzzy on the
> edges of the roofs, but maybe we can fix this in a second version. You see
> the fortress well in the city park, which I think is awesome.
>
>
>
> We’ve also generated a dtm-style hillshade of the 2017 data from the
> Administration de la navigation aérienne. The quality isn’t as high as the
> 2019 scan, but it covers bits of the neighbouring countries which we
> thought could be useful for mappers there.
>
>
>
> These three layers are available for mapping by everyone today.
>
> In JOSM, the 10 cm imagery is ‘geoportail.lu ortho technique 2019 (10cm)’
> in the Imagery menu and the two hillshades are at the bottom of that menu,
> in the ‘elevation’ submenu.
>
> In iD, for now, you have to add these as custom layers like this:
>
>
>
> 10 cm photos:
> https://wmts1.geoportail.lu/opendata/wmts/ortho_2019_winter/GLOBAL_WEBMERCATOR_4_V3/{z}/{x}/{y}.jpeg
> lidar hillshade:
> https://lidar-hillshade-2019.openstreetmap.lu/layer/mappers_delight_lidar_hillshade_2019_reprojected/{z}/{x}/{y}.png
> ana dtm :
> https://ana-dtm-2017.openstreetmap.lu/layer/ana_dtm_2017_hillshading/{z}/{x}/{y}.png
>
> Finally, the hillshade makes a nice ‘pop’ effect when combined with a bit
> of transparency!
>
>
>
> If you just want to explore the hillshade for hours (I do), it’s at
> https://lidar-hillshade-2019.openstreetmap.lu/
>
> Happy mapping, and let me know if you like it and find it useful,
>
> Guillaume
> _______________________________________________
> talk-lu mailing list
> talk-lu at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk-lu
>
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