Via @pierre_markuse: Look at this super-interesting and well-written fifth part of the Gentle Introduction to #GDAL series by @rsimmon, this time dealing with shaded relief. #remotesensing #gis #dataviz #cartography #remotesensing https://medium.com/@robsimmon/a-gentle-introduction-to-gdal-part-5-shaded-relief-ec29601db654

ok I'm pretty convinced that #GDAL's MDIM arraySpecs is not being parsed correctly by the gdalmdimtranslate_lib, but it is working when the spec is called by GetView() in cpp or python

finding examples is tough!! it's teaching me numpy indexing too

wow just took a stab in the dark on #GDAL (>=3.7.0) and tried

vrt://<dsn>?ovr=-1

in the hope that it means "native data level, ignore all overviews" - and, it does!

#gdal to the rescue, use SHAPE-ZIP if the server supports, still can't unpick the curve thing easily without more C++

ftw: "geoserver/wfs?OUTPUT_FORMAT=SHAPE-ZIP"

many data #spatial providers don't even know about the benefits of well structured GeoTIFF (let alone the buzz of COG, STAC, Zarr, etc)

I reach out to providers, but more often than not there's just another individual there scratching head at my crazy email (who even reads bathymetry on the fly from a url, nuts right...)

at institution I can try collectively to feedback, but the #python and #rstats and #gdal communities could join forces here - is there something in the #xarray zone?

I had a bit of fun cramming moderately-complicated spatial SQL into the "-sql" parameter of ogr2ogr. Now you can have fun with it too!

https://billmorris.io/shoals/posts/2023-08-17_land-tiles/ #mapping #sql #gdal #tiles

Has anyone had any luck using #GDAL 's SAFE driver to download Sentinel-1 from Planetary Computer STAC endpoints? When I try `gdalinfo -if SAFE /vsicurl/<some_url>` I get "not recognized as a supported file format" -- is there a correct way to do this?

I'm suspecting the authentication junk at the end of Planetary Computer URLs is causing issues.

https://gdal.org/drivers/raster/safe.html

#GISChat #rspatial

With #gdal, is there a way to resample a raster to a coarser grid by aggregating to arbitrary quantiles?

In `gdalwarp` there is the first an third quartile implemented as resampling method, but how to calculate the 95th percentile?

It seems to be possible with #grass `r.resamp.stats` so my guess is there is some way with gdal too.

@EvenRouault @mdsumner

gee I just figured out external overviews in #GDAL ... it's so easy! You make a COG with the lower resolution overviews and call it "original_file.fmt.ovr" and stick it next to the "original_file.fmt" (can be original.vrt for any other source) - I'm sure there's more to it but this alone is amazing and opens up so much

#rasterio sets the benchmark for #GDAL as central in the handling of general "datasets to open" schemes

https://github.com/rasterio/rasterio/discussions/2897

this repo runs a regular github actions #gha #rstats task to update with latest data, it's pretty rough but represents a lot of consolidated learnings for me

it gets some recent spatial data using #GDAL (sea ice concentration, and research vessel location) and makes a map, it's fairly simple so might be of interest if you're keen to get github actions doing work :)

https://github.com/mdsumner/seaice.map

thanks to @mattcowgill for help with gha 👌

it is *so good* to be able to load gdal_translate args onto a dsn with vrt:// string, amazing - it just kicked in for me, I can add "scale" without that intermediate VRT file step #GDAL v3.7.0

probably the single best resource for #GDAL techniques and code examples is the autotest suite:

https://github.com/rouault/gdal/tree/master/autotest

it's all in Python but it's not *about Python*, it's about GDAL and all the superpower flexible and efficient facilities it has

takes a bit of orientation to understand what's in there and how to explore, but it's worth it 👌

oh free hot tip TIL you can #GDAL vector VRT to reproject any source... something I've been trying to learn to do in cpp 😅 so much easier to wrap a little vrt text and hit that for queries #rstats

shove your source and crs in that text and hit with favourite gdal tool

https://gdal.org/drivers/vector/vrt.html#example-reprojected-layer

This week @hansakwast is teaching #GroundwatCh #ErasmusMundus MSc students the course Programming for Geospatial Hydrological Applications at @ihedelft. You can follow along for free at GIS OpenCourseWare! #GDAL #CLI #Python #PCRaster #PyQGIS https://courses.gisopencourseware.org/

"Mastering GDAL Tools" provides complete course materials for an introduction to GDAL and OGR command-line programs to create workflows for processing raster and vector data and organizing spatial ETL pipelines #gdal

https://courses.spatialthoughts.com/gdal-tools.html

Pacific Crest Trail Viewshed [animation]
--
https://youtu.be/tmY27ZIVfpA <-- shared video
--
H/T Doug Newcombe
“This animation is a viewshed of the Pacific Crest Trail. A viewshed shows all surrounding terrain that is visible from a given point on the trail. The viewshed is taken at 1/10 of a mile increments. Visible terrain is light colored, invisible terrain is darker. Views are without regard for vegetation or tree cover…”
“The following viewsheds were created with GDAL, one tif for every tenth
of a mile along the 2,650 mile Pacific Crest Trail. Stitched together
with ffmpeg..”
#GIS #spatial #mapping #viewsheds #spatialanalysis #3D #elevation #Pacific #PNW #PacificCrestTrail #DEM #GDAL #ffmpeg #viewshed #animation #hiking #trail

#GDAL 3.7 supports #GTFS, woot!

https://gdal.org/drivers/vector/gtfs.html

I have some rasters of multi GB size.
Without a gripe, call gdal_translate to compress those guys.
With ‘-co’ I set COMPRESS=ZSTD
and PREDICTOR=2 for optimal squeeze.
And only then proceed to analyze.

#GISChat #gdal #LimriGIS #ZSTD #raster

I feel like this was a really productive code sprint, with lots of issues created in #gdal #qgis and #pygeoapi. There were some great discussions, and even some live coding 😀 Thanks to everyone who showed up online, and in-person! 👋 Hope to see you all soon! #CODESPRINT21 #OGCAPI #OGC #standards @gdal @pygeoapi @qgis