I got an elevation raster map which I interpolate from a point cloud with `v.surf.bspline`.

Then I digitize a couple of points in a new vector layer.

With `v.drape` I'm able to get a height from the raster to those 2D points.

I'm exporting the result to DXF and everything is fine, the points are in 3D.

When I'm digitizing lines, the same workflow leads me to lines that are still in 2D.

I'm missing something !

Thank you.



**EDIT 1** :

I made a polyline (not in 3D a 2D) in Drafsight, z is equal to 0. I saved it in .DXF.

Then I imported it with `v.in.dxf` to grass, gave it to `v.drape` with my elevation raster map.

And finally, I ran :

    v.out.ogr -z input=gloubiDrape@PERMANENT type=point,line,boundary,centroid,area,face,kernel,auto dsn=gloubidrape.dxf format=DXF

With the following output :

    WARNING: The combination of types is not supported by all formats.
    WARNING: No points found, but requested to be exported. Will skip this geometry type.
    WARNING: No boundaries found, but requested to be exported. Will skip this geometry type.
    WARNING: No areas found, but requested to be exported. Will skip this geometry type.
    WARNING: No centroids found, but requested to be exported. Will skip this geometry type.
    WARNING: No faces found, but requested to be exported. Will skip this geometry type.
    WARNING: No kernels found, but requested to be exported. Will skip this geometry type.
    WARNING: Vector map <gloubiDrape@PERMANENT> is 3D. Use format specific layer creation options (parameter 'lco') to export in 3D rather than 2D (default)
    ERROR 1: DXF layer does not support arbitrary field
    creation, field 'cat' not created.
    ERROR 1: DXF layer does not support arbitrary field
    creation, field 'layer' not created.
    ERROR 1: DXF layer does not support arbitrary field
    creation, field 'entity' not created.
    ERROR 1: DXF layer does not support arbitrary field
    creation, field 'label' not created.
    Exporting 1 geometries...
    Exporting 0 areas (may take some time)...
    Exporting 0 faces (may take some time) ...
    Exporting 0 kernels...
    v.out.ogr complete. 1 features written to <gloubiDrape> (DXF).

I opened this new .DXF with draftsight, now z is not equal to 0, it is equal to 329 which is consistent with my elevation map but it is still flat.

**EDIT 2** :

When I show attribute data for gloubiDrape my 3Dvector map, under browse data tab I get :

    cat layer entity label
    1 0 lwpolyline
    2 0 lwpolyline

and under manage tables :

    columnName dataType dataLength
    cat integer 11
    layer character 255
    entity character 255
    label character 255