NZ DEM (elevation) Files

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NZ DEM (elevation) Files

Postby wildwanderer » Wed 10 Oct, 2018 4:17 pm

Does anyone know where I can get high quality DEM files for NZ south island?

The nz govt site has them in geo tiff but Ive no idea how to convert to hgt.

I'm after 1 sec or better accuracy.
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Re: NZ DEM (elevation) Files

Postby keithy » Wed 10 Oct, 2018 11:04 pm

I have previously download the dem data from NASA/USGS. https://earthexplorer.usgs.gov/ I think it was also in geotiff if you got individual files which you need to convert to hgt. Although it looks like you can get some hgt files zipped. I haven't used them since 2016. https://e4ftl01.cr.usgs.gov/MEASURES/SRTMGL1.003/ you need to make an account to download.

For oruxmaps on my devices the 1 arc sec hgt is about 25Mb each hgt file so I stick with the 3 arc sec about 2.7Mb each file

Jonathan de Ferranti has made some corrections to the 3 arc sec SRTM http://viewfinderpanoramas.org/Coverage ... s_org3.htm which you can download in hgt. He has been slowly adding 1 arc sec dem but mainly in Europe. I've currently got his 3 arc sec files for NZ on my phone and tablet.

Also there was meant to be a reprocessed SRTM dem by NASA (NASADEM) was meant to be released soon but I haven't been following it.
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Re: NZ DEM (elevation) Files

Postby michael_p » Thu 11 Oct, 2018 8:45 am

Converter here: https://mygeodata.cloud/converter/geotiff-to-hgt . Never used it so not sure how good or bad it is, and free service is limited (check the plans page for details).

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Re: NZ DEM (elevation) Files

Postby wildwanderer » Thu 11 Oct, 2018 4:21 pm

Cheers Guys,

I'l have a look into the earth explorer site.

Unfortunately the mygeodata tool is limited to 5mb exports without paying. Which isnt large enough for 1 sec 25mb HGT files
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Re: NZ DEM (elevation) Files

Postby tastrax » Thu 11 Oct, 2018 5:48 pm

Cheers - Phil

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Re: NZ DEM (elevation) Files

Postby tastrax » Thu 11 Oct, 2018 5:50 pm

Cheers - Phil

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Re: NZ DEM (elevation) Files

Postby wildwanderer » Thu 11 Oct, 2018 7:58 pm

tastrax wrote:8M model - about 16gb - https://data.linz.govt.nz/layer/51768-n ... odel-2012/


These are great except they are only available in tiff. I need a way to convert to HGT so they are readable on my map app.
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Re: NZ DEM (elevation) Files

Postby michael_p » Thu 11 Oct, 2018 8:55 pm

wildwanderer wrote:Unfortunately the mygeodata tool is limited to 5mb exports without paying. Which isnt large enough for 1 sec 25mb HGT files

Thank you. Handy to know how limited that "free" service is.

Did a quick search and apparently gdal_translate can convert geotiff to hgt. Info on Gdal: https://www.gdal.org/ . Have a look at the answer to this question: https://gis.stackexchange.com/questions ... iff-to-dem .

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Re: NZ DEM (elevation) Files

Postby tastrax » Thu 11 Oct, 2018 9:10 pm

You can also use QGIS processing to translate the files (which uses the above GDAL process)
Cheers - Phil

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