[GRASS5] v.in,dxf

[Roger S. Miller]

Rich Shepard wrote:

>   v.in.dxf almost works. Let me clarify that: it may actually be working now
> that I've built a new installation. I'll check that over the weekend.

Rich, have you been working on the code?  The version that was packed with
beta11 doesn't handle splines and that's really the only major problem I
had when I tried to import a DXF from ACAD/2k.

Markus, I took a quick look at the CVS release and from the comments it
doesn't appear that work is underway to add new capabilities.  Mostly a
much-needed clean-up.

I recently needed to import a ACAD/2K dxf and nothing I had access to
would swallow it (including my apparently aging version of AC Lite).  I've
been writing my own programs to read, process and write DXF for several
years, so I just adapted one of those programs to read splines and write
the equivalent lines.

I'm willing to give my spline routine to someone who might incorporate it
into v.in.dxf.  My program works, but it isn't full featured and it is
just a simple cubic b-spline, so might not even be the right kind of
spline. The DXF files contain several codes that I don't interpret to
produce the lines.

In the course of doing that I found a GPLed C++ class library called DIME
(Dxf Import Manipulation and Export).  I decided that it would probably be
better to incorporate DIME in any future coding I have to do rather than
continue my hacking, but I didn't do it right away because I didn't want
to move to C++.  I haven't used DIME at all, yet.

Has anyone thought much about incorporate DIME into v.in.dxf/v.out.dxf ?

>   The potential problem with v.out.dxf is for which version of AutoCAD it
> should be targeted. Apparently ACAD/2K is quite different from earlier
> versions.

As far as I know, the main version difference that would effect v.out.dxf
is the difference between the old-style POLYLINE and the new-style
LWPOLYLINE used in ACAD/R14 and later.  LWPOLYLINE would be a better
choice, as it's simpler, but the old POLYLINE format is the only one
that's sure to work with old software.

There are also revisions to the dxf header, so that my old AC lite program
won't even read through the header from the new 2k dxf.  AC Lite was the
only app I had that reported a problem with the header.

David, is the problem of importing a dxf substantially different from
importing a shapefile?  Even with the generic vector import capability,
won't there still be a place for something like DIME to handle the dxf
format?


Roger Miller