Folks,
In response to recent discussions about the need for SDTS to MIF (or TAB)
translation, I have decided to write a free sdts2mif translator. I am not
normally a Mapinfo user, and so have a limited knowledge of Mapinfo, mostly
garnered in the past from work on mif and TAB translators. As such I am
interested on feedback indicating how to write optimally useful files for
use in Mapinfo. Bill Thoen has kindly offered to help me a bit in this
regard.
I have read back through a couple dozen SDTS messages in the Mapinfo-L
archive, and this is what I understand:
o Vertical Mapper (as of a very recent version) includes SDTS DEM import,
so there isn't really much need for me to support DEMs. Based on this
I will concentrate on SDTS TVP (Topological Vector Profile) import. If
DEMs are an issue, I can easily provide an SDTS DEM to GeoTIFF translator.
o MID/MIF is equally useable in Mapinfo as TAB/DAT files, so it is sufficient
to write MID/MIF.
o Mapinfo is primarily (only?) available for Windows so it is sufficient to
produce Windows .exe files for a conversion utility. (Note other platforms
can be supported if desired. I normally write platform agnostic text
mode programs).
One question I have relates to the SDTS attribute data model. SDTS vector
features (lines, polygons, etc) can have links to zero or more attribute
records. These records can be in one or more tables. What I have done in
the past when writing an SDTS2Shape translator was scan the whole vector layer
for attribute references, and then establish an attribute schema which is the
merged form of all tables references from the layer. I will do the same for
Mapinfo output.
However, some vector features have links to more than one records in the same
table. For instance, some elevation contour datasets have more than one
elevation record associated with contours. This seems to occur when several
contour have been collapsed into one in very dense areas. The result is that
one feature should be able to have several ELEVATION values associated with it.
For now I am going to just assign one of the elevation values at random, but
does anyone have an opinion on a better way of handling this? Is it a major
issue?
Another question I have is about what sort of graphical elements I should
be using in the MIF file. Is it important that this be configurable on the
translator command line?
Finally, a few weeks ago someone asked if the FME support for SDTS was
read/write or not. FME only reads SDTS datasets at this time, but the
results can be written to any supported writable format, including MIF and TAB.
As usual, a variety of manipulation can be applied during translation. FME
is a good value for anyone needing to do an assortment of data translation.
It isn't my intention to displace FME purchases, and in fact Safe Software
funded the development of my underlying OpenSource SDTS library.
Best regards,
---------------------------------------+--------------------------------------
I set the clouds in motion - turned up | Frank Warmerdam, [EMAIL PROTECTED]
light and sound - activate the windows | http://members.home.com/warmerda
and watch the world go round - Rush | Geospatial Programmer for Rent
----------------------------------------------------------------------
To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put
"unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED]
