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Optimal way to store and use DEM data

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Nikkitta Nikkitta
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Optimal way to store and use DEM data

Hi,

I want to use ASTER GDEM v2 data for the whole world from local disk.
What is the best way and file format to store this data locally and use it with osgEarth?

Currently I'm using single GeoTIFF file for the whole world of SRTMv4.1 with *.ovr created.
It has size of 21 GB and it take some time to load in osgEarth even with cache enabled.

The way of storing data
ASTER source GeoTIFF data has size of 1.4 TB. So my guess is to:
1. Store down-scaled data for the whole world in 1 file for distant views of Earth.
2. Store detailed data for regions (like 5x5 degrees) in separate files, to load needed region when the camera is close to the ground.

This approach will allow me to copy only needed regions in case of installing my app on other PCs.
But I want to be sure that this is the correct idea. Do you have any objection?

DEM file formats
Another problem is that I'm not sure that I use optimal and fastest file format (GeoTIFF) for DEM.
Currently I'm using ECW (WGS84) to store imagery, and GeoTIFF to store DEM.
In GlobalMapper I've found DEM formats like DTED and others.
Which one is optimal for use with osgEarth and for my needs?
Best regards,
Nikita Petrov
gwaldron gwaldron
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Re: Optimal way to store and use DEM data

A couple things:

First, if you use a GeoTIFF directly, make sure it is projected and internally tiled, as detailed here:
http://docs.osgearth.org/en/latest/data.html#tips-for-preparing-your-own-data

If this is still not fast enough you may need to build a pre-tiled dataset using osgearth_package.

Glenn Waldron / Pelican Mapping / @glennwaldron
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