Cannot visualise .3d in EPSG:27700

[aricooperdavis]

I am trying to visualise a .3d file that uses a station fixed in EPSG:27700.

When I load it into CaveView I get the following console messages:

CaveView v2.7.3
Survex .3d version  v8
looking up CRS code EPSG: 27700
Reprojecting from +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +nadgrids=OSTN15_NTv2_OSGBtoETRS.gsb +units=m +no_defs +type=crs to EPSG:3857
Unable to find mandatory grid 'OSTN15_NTv2_OSGBtoETRS.gsb'

This results in pop-up alert():

Failed loading cave information: TypeError: point is undefined.

[aricooperdavis]

This is probably a limitation in using proj4js with grid based datums like EPSG:27700?

[aardgoose]

Ari, Forgot to say, the latest version should work, it will be happy if adjustment grids aren't available now (positions will be slightly shifted but locations are correct within a few metres without the UK grid file in any case. If you do want to use grid files, they should be placed in the same directory as the survey file(s).