<div dir="ltr">+gdal-dev<div><br></div><div>Some hackish test code I had laying around from last year...</div><div><br></div><div><a href="https://gist.github.com/schwehr/01f6604afc7757ea0a676f0eb28be582">https://gist.github.com/schwehr/01f6604afc7757ea0a676f0eb28be582</a><br><div><br></div><div>You might also be able to just write 80 layers of u-v, pick out pairs for each depth layer and have the rendering system do the conversion(s). You could use whatever you want once you have a geotiff. In this screenshot, I made an 80-layer geotiff of u and v alternating layers and uploaded that to Earth Engine. It's been a long time since I heavily used mapserver, but you could probably do the same there.</div><div><br></div><div><a href="https://www.flickr.com/photos/schwehr/26895009754/">https://www.flickr.com/photos/schwehr/26895009754/</a><br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jun 6, 2016 at 7:51 AM, Stephen Woodbridge <span dir="ltr"><<a href="mailto:woodbri@swoodbridge.com" target="_blank">woodbri@swoodbridge.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">On 6/5/2016 2:04 PM, Kurt Schwehr wrote:<br>
</span><span class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Stephen,<br>
<br>
Take a look at these two discussions for starters on working with hycom:<br>
<br>
<a href="http://gis.stackexchange.com/questions/167155/how-can-i-make-geotiffs-of-individual-depth-layers-in-the-hycom-ocean-circulatio" rel="noreferrer" target="_blank">http://gis.stackexchange.com/questions/167155/how-can-i-make-geotiffs-of-individual-depth-layers-in-the-hycom-ocean-circulatio</a><br>
</blockquote>
<br></span>
Hi Kurt,<br>
<br>
In the link above you mention:<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I've got some code written the does things like calculate the speed<br>
inm/s from the UV and creates a geotiff, etc<br>
</blockquote>
<br>
Can you share this code, it sounds like exactly what I need for the current vectors? And I'm interested in figuring out how to read/write and work with the netcdf files.<br>
<br>
I think for now I'll work with the "u" datasets as they seem that they will be much easier place to start.<br>
<br>
Thanks,<br>
-Steve<br>
<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">
<a href="http://gis.stackexchange.com/questions/170882/how-can-a-make-a-netcdf-with-subgroups-smaller" rel="noreferrer" target="_blank">http://gis.stackexchange.com/questions/170882/how-can-a-make-a-netcdf-with-subgroups-smaller</a><br>
<br>
You should start with the regular grids. e.g.<br>
<br>
<a href="ftp://ftp.hycom.org/datasets/GLBu0.08/expt_91.1/data/hindcasts/2015/hycom_glb_911_2015093000_t000_uv3z.nc" rel="noreferrer" target="_blank">ftp://ftp.hycom.org/datasets/GLBu0.08/expt_91.1/data/hindcasts/2015/hycom_glb_911_2015093000_t000_uv3z.nc</a><br>
<br>
Make an 80 layer geotiff from the u/v and then use mapserver as Even<br>
suggested.<br>
<br>
-kurt<br>
<br>
<br>
On Sat, Jun 4, 2016 at 6:29 AM, Even Rouault <<a href="mailto:even.rouault@spatialys.com" target="_blank">even.rouault@spatialys.com</a><br></span><div><div class="h5">
<mailto:<a href="mailto:even.rouault@spatialys.com" target="_blank">even.rouault@spatialys.com</a>>> wrote:<br>
<br>
Hi,<br>
><br>
> I want to convert some HYCOM data into GTiff format and I'm a little<br>
> lost on how to get started, whether I can do what I need just using a<br>
> vrt or if I'm going to have to write code to process the data.<br>
><br>
> To start with I have placed gdalinfo on one file here:<br>
> <a href="http://imaptools.com:8080/dl/hycom-gdalinfo.txt" rel="noreferrer" target="_blank">http://imaptools.com:8080/dl/hycom-gdalinfo.txt</a><br>
><br>
> The data comes from <a href="http://hycom.org/dataserver/glb-analysis" rel="noreferrer" target="_blank">http://hycom.org/dataserver/glb-analysis</a><br>
> and I will need to be using GLBa0.08 dataset.<br>
><br>
> I have two use cases:<br>
><br>
> 1) The simple one is to extract say Band 1 into a georeferenced GTiff<br>
> and apply color to using color ranges without loosing the NODATA. I<br>
> think I can do later using .vrt, correct?<br>
<br>
gdaldem color-relief can output to a VRT, but given that this netCDF<br>
file is<br>
georeferenced through a geolocation array, you'll likely have first<br>
to run<br>
gdalwarp -geoloc to have something useful at the end.<br>
<br>
><br>
> I'm not sure how to deal with the georeferencing, because the download<br>
> site says: "Native hycom .[ab] data converted to NetCDF on native<br>
> Mercator-curvilinear HYCOM horizontal grid" but that does not seem in<br>
> sync with the Metadata in the file.<br>
><br>
> 2) The more complicated case is that there are two files:<br>
> a) eastward_sea_water_velocity (aka: u, u-velocity)<br>
> b) northward_sea_water_velocity (aka: v, v-velocity)<br>
> that I would like to use to create a grid of vectors with arrowheads<br>
> using u and v to define the vector and where the color of the vector is<br>
> related to the magnitude of its length. Ultimately this data will get<br>
> rendered via mapserver so I'm wondering if I can do this via a GTiff or<br>
> if I will have to resort to creating a massive point shapefile with<br>
> attributes of angle and magnitude and use a symbol. It seems like it<br>
> would be best if I can keep the data as a GTiff and then sample the<br>
> points and render the vectors on the fly for when you zoom in/out.<br>
<br>
See<br>
<a href="http://mapserver.org/input/vector/vector_field.html" rel="noreferrer" target="_blank">http://mapserver.org/input/vector/vector_field.html</a><br>
<br>
You don't need to create a vector file.<br>
<br>
You'll have to preprocess your file to get the u and v bands in the same<br>
raster.<br>
<br>
Even<br>
<br>
--<br>
Spatialys - Geospatial professional services<br>
<a href="http://www.spatialys.com" rel="noreferrer" target="_blank">http://www.spatialys.com</a><br>
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