HGT files for DEM in 2025

[YvanCB]

Hello,

The altitude information got better and better.
In France, IGN gives us ".asc files" with 2 available definitions:

• 1x1 meter
• 5x5 meters

The web site is there:
(https://geoservices.ign.fr/rgealti)

Oruxmaps uses HGT files (SRTM1 1"x1" or SRTM3 3"x3") for altitude information.
The best definition for this format is limited to 1"x1".
In the post below it's mentionned that HGT can manage 0.5" but I not sure that it's true:
https://oruxmaps.com/forum/index.php?topic=40692.msg.

The SRTM format is explained here:
https://docs.safe.com/fme/2019.1/html/FME_Desktop_Documentation/FME_ReadersWriters/srtmhgt/srtmhgt.htm

My question:
Is it possible to change OruxMaps in a way to use files with better defenition than 1"x1"?

Regards.

Yvan

[Maki]

I guess the best thing is to try. :-)
If I recall correstly you have to use ".dem + .hdr" format but I haven't tried. Personally, I think in most cases there is very little benefit, if any, using high resolution DEMs because the GPS position is not that accurate so you would be adding just noise.

As a side note, RGEAlti is not that good in a lot of areas; I mean, it's way better than SRTM but still old data, mostly radar based. If available I suggest to get LidarHD instead (https://geoservices.ign.fr/lidarhd), it's heavier to download but you can easily downsample to reasonable size with QGIS/GDAL. It's just another level.

[YvanCB]

Hello,
I am new to using Qgis. I have tried to use it, but it is too difficult for me.
I have read many articles and watched tons of videos, but I still cannot do this kind of work.
I think I am going to give up on my project. It is not that important.
Best regards.