question about shp2tile

[Zhonghai Wang]

Hi guys,

I've tried to make a efficient map layer with the commands shp2tile,
tile4ms, and shptree, but something seems not right, because MapServer can
not draw the maps. I've made a test in a seperate folder, and I've done the
following processes:

***
data -- Forests.shp (for a country)
***
1. >shp2tile -r 50 -c 50 Forests.shp Forests_Test.shp
>>>results for this step: shp, shx, and dbf files, there is no prj file for
the output file
>>>error info on the console: failed to create shp Forests_Test.shp -1833

2. >tile4ms ---- get the tileindex.shx, tileindex.shp and
tileindex.dbffiles for the Forests_Test.shp, there is still no prj
file for
tileindex.shp
>>>no error messages appear at this step

3. >shptree -- to genetare .qix file for all shapefiles in this subfolder
>>> results for this step: Forests.qix, Forests_Test.qix, and tileindex.qix
>>>no error info on the console

but, only if I set DATA "Forests" in the layer object the map will be
rendered, others like DATA "Forests_Test" or TTILEINDEX "tileindex" TILEITEM
"location" do not work, the server simply sends back a blank image.

did I make any mistakes or it really do not work well. (I am using MS4W
4.8.1)

I guess some errors occur when I perform the command shp2tile.

thanks for any further info.

zhonghai

On 5/18/06, Zhonghai Wang <zhonghaiw at gmail.com> wrote:
>
>  Hi Bob, Steve,
>
> thank you very much for all these helpful clues, now I think I've got the
> points of the shp2tile command, it's really a good tool to slice shapefile.
>
> zhonghai
>
>  On 5/18/06, Stephen Woodbridge <woodbri at swoodbridge.com> wrote:
> >
> > Zhonghai Wang wrote:
> > > Hi folks,
> > >
> > > I have a large shapefile, now I am trying to use shp2tile command to
> > > slice it into pieces, with -r and -c is ok, but I do not fully
> > > understand the -q parameter, what does it actually mean? and what
> > number
> > > should a use for this parameter normally?
> > >
> > > or something like this? -- >shp2tile -q 10000 input_shapefile
> > > output_shapefile
> >
> > Hi Zhonghai,
> >
> > The -r -c option breaks the extents of your shapefile into R x C rows
> > and columns and then tries to fit the objects into the best tile. I any
> > tile crosses a tile boundary by 5-10% then it is put into a "supertile"
> > the could be the same extents as the original shape file. So typically
> > you will end up with r X c + 1 tiles.
> >
> > The -q N option splits the extents in half either vertically or
> > horizontally and then sorts the objects into the 2 halves or put them in
> >
> > a supertile. Then if the either of the two halves has more than N
> > objects it is again split in half and this continues until all files
> > have less than N objects. This can cause some strange effects like tiles
> > with 1 or a small number of objects and most tiles will have less than N
> > objects in them. Since this algorithm tends to spatially cluster objects
> > in a file, there is a good chance that if you need the file that all or
> > most objects in the file will be used.
> >
> > I recommend trying numbers like 10,000 and 20,000 as you initial tries.
> > I think you should probably not use numbers less then 8000, but it is
> > really up to you to try and measure the results to find what works best
> > for your data.
> >
> > -Steve W.
> >
>
>
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