It seems that obj to v3d conversion is possible and represents a transformation of 3D models saved in Wavefront object format (.obj) to ViaCAD 3D format (.v3d). It should be possible to export or convert obj to v3d with some dedicated 3D modeling / conversion tools, for example the 3D Object Converter.
Open OBJ file Open V3D file3D viewer and converter with huge file type support