Matt Wilkie wrote:
I am combining some GIS data where each layer is divided to around
thousand
separare shapefiles by mapsheets.
We are in the same boat. For the moment I'm exploring the approach of
aggregrating map sheets, creating super tiles, until we approach the
2gb shapefile limit. I've not found a good method for predicting when
we'll hit that limit though so it's error prone with a lot of repeats.
Looking forward, the as-yet unreleased file geodatabase API/spec would
be a solution. ESRI has said they will do so, but it's been several
years since they first announced it and when it is finally is released
there is no guarantee it will be under license terms open source
projects can use. This isn't to say it will be unusable either, we
just don't know.
I've been reading about Binary XML, which has an open source library
published by Cuberwerx, http://www.cubewerx.com/bxml. They say it is a
drop in replacement for XML. Perhaps binary gml would be a good format
for >2gb data packages? How much work would it be to add this to
gdal/ogr? I invite developers to submit price estimates to me. I don't
have an active project assigned to this or a budget, but I can't get
one without an idea of what to ask for either.
Folks,
I'm by no way a vector expert, but for this kind of stuff I'd go the
postgis way, at least for intermediate storage. You won't have any 2GB
limit on vector db size, have reasonable fast rw access to the data, and
will be able to do spatial operations on the db directly. Once you've go
all your data in the db the way you want it, you can export to any ogr
supported vector format.
For a platform independent way of distributing vector files that are
>2GB, I'd check out spatialite; however, I don't know in what shape
ogr's support for real spatialite db's is, so you'd have to do some
research here. Note that, once 32bit windows OS come in sight, this
might put a barrier at 2GB no matter what vector file format you use,
though I'm not sure about that either. I try not to use windows if
possible :-)
just my 2 cents...
Vincent.
best regards,
matt wilkie
--------------------------------------------
Geomatics Analyst
Information Management and Technology
Yukon Department of Environment
10 Burns Road * Whitehorse, Yukon * Y1A 4Y9
867-667-8133 Tel * 867-393-7003 Fax
http://environmentyukon.gov.yk.ca/geomatics/
--------------------------------------------
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