[CONTEXT CAPTURE] - OSGM15 geoid model in GTX format

Hi all,

Did anyone come across uploading a geoid model into Context Capture when undertaking aerial surveying in UK. An OSGM15 geoid model file in .gtx format is required to be uploaded, so I was wondering whether anyone has already obtained the geoid model in this format.

I have tried converting a geoid .txt file from  https://www.ordnancesurvey.co.uk/business-and-government/help-and-support/navigation-technology/os-net/formats-for-developers.html into a .gtx file using  Eye4software (hydromagic), however that does not seem to work.

Many thanks