ESRI Shape Output (v.out.shape) !

[Rich Shepard]

On Wed, 17 May 2000, David D Gray wrote:

> It does make sense to use this, and in fact, as I have described, that
> is exactly what I have done with huge amounts of data. I started to
> develop the shapefile import stuff, however, because I couldn't
> find a way to export DLG's from ArcView, and the other side of the coin
> is that, some people may not have ArcView, less well endowed GIS maynot
> so easily have the DLG support facilities that we can take for granted
> with the `giants'.(As Alejandro has just pointed out) But surely all
> the serious topological formats - DLG, dig, e00, SDTS even, are
> much-of-a-muchness under the skin, I mean in terms of their data
> structures and links. So I am not quite sure what you mean by using
> specifically DLG as an import/export intermediate. Our intermediate
> would just be an API consisting of raw structures in memory and the
> routines to process them.
 
David,

  Aha! Now I understand better what you are suggesting. I was thinking of
our situation: we have GRASS and MapInfo. Data are available from various
sources in different formats, but the only ones I'll be transferring to
GRASS from what we've generated are the MI ones. So, I wasn't thinking of
temporary, memory structures but of disk files.
 
> BTW. Did you get the E-mail I sent you about this?

  Yes. I meant to respond earlier; thought I did. Let me try again here.

  I'm starting to design the MI<->GRASS filters from the MI side. I'll be
very happy to use your code to get the data into GRASS once I get it out of
MI, or vice-versa. No sense re-inventing the wheel, as you noted.

  The MI file format is very well documented and is easy to parse into data
structures. The trick -- for me at least -- is understanding the GRASS data
structures so I can put the right values in the proper files.

  The other hang up is my understanding of the "arc-node" format in
practical terms. A MI region (polygon) is a list of nodes with the first and
last nodes having identical values. I've no idea how to separate this one
line into meaningful segments (arcs) for input into GRASS. I'm certainly
open to ideas, thoughts or solutions, for I've never had to deal with this
before.

Thanks,

Rich 

Dr. Richard B. Shepard, President

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