Terrain Import Issues

Morning. I've been looking at importing a few terrains and then combining them, moving on as much as I can from MX because the less you need to use other programs the better. The nature of the project is such that we have a LIDAR DTM as an IMG file, a Bathymetric XYZ file, and a Topographic survey, which was received as both a 3D DWG and an INP. These then need to be combined as a complex terrain so the best available information is used to create an overall terrain model for use. I've been having some trouble, so I'm hoping someone else has found the method I'm missing or knows what I'm doing wrong.

LIDAR Survey

The IMG received no longer appears as an import option, which it previously was in MX SS4. Going through the various import options, I haven't been able to find a way to import this in OpenRoads. So it currently looks like being a matter of import using MX, then import again from the MODEL.FIL.

Bathymetric Survey

In the case of the bathymetric survey, this can be imported simply enough using "Create Terrain Model from Ascii file". The issue comes then from needing to convert the model's Z-scale from positive to negative depths, and then Z shift from Chart datum to Ordnance datum. This kind of edit does not seem to be an option in OR, and as before I appear to have to process through MX before bringing the terrain into OR.

Topographic Survey

This was received as both an MX input file (.INP) and as a 3D DWG. The INP is only 3.5MB in size, nothing overly large or complex. Attempting to use the graphical filter, the tool appears to only include levels which have been selected into the list for building up the filter, and will freeze when trying to select a large number of elements in order to quickly work through the levels for inclusion. Once this was achieved, there were a number of levels, which despite being included in the filter, were ignored by the process, and when trying to process the terrain I experienced several crashes.

Abandoning this, I decided to import the survey itself from my MX model.fil. This takes a very long time, and does not bring through the feature definitions. Features then have to be defined, one-by-one, and then included into the terrain, which will be very time consuming. Additionally, the L??? string for spot levels is imported as a breakline and point features do not appear to have been imported.

Importing the triangulations, of which there are 3 due to the river running through the scheme, created another issue as they are imported and appended into a whole terrain. Ignoring the extents of the triangulations themselves, OR assumes to create triangles for the full possible extent of the survey. Slivers has no effect, whilst maximum triangle length creates holes where there should not, and leaves triangles where there should be gaps, and Edit Model will not allow me to remove the necessary triangles. Importing the boundary strings from MX, since there does not seem to be a way to create model boundaries as effectively in OR, the tool defaults to internal trim method and cannot be changed back to external, whereby I am left with every triangle I do not require, and none of the ones I do.

So guys and gals, what am I missing?