Anyone know what I can use to convert a geoid surface stored as , BYN into .GTX for use with PROJ4?

The CCG2013A vertical datum and geoid model from NRCan is only available, as far as I can find, in BYN format.

2 Answers 2


You can download a demo verion of the Hydromagic software from https://www.eye4software.com/download/

It includes a geoid converter freeware: https://www.eye4software.com/hydromagic/documentation/manual/utilities/geoid-file-conversion/

Supported file types are .geo, .ggf, .gsf, .byn, .bin, .grd, .txt, .gtx as source and destination.

They offer a bunch of geoid files in their .geo format at https://www.eye4software.com/hydromagic/documentation/geoid-models/

Disclosure: I'm not affiliated with the software company.


GDAL will support BYN files in an upcoming release. However, it is unclear when this release will be compiled for windows.

In the meantime, I've uploaded converted GTX files for HT2_0 and CGG2013 so that they are easily accessible until the GDAL capabilities come into effect.

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