question about shp2tile

[Zhonghai Wang]

Hi Steve,

I've tried again like you said, this time I get something, but still no map
images are rendered.

the version is exactly the same, updated version.

First test example:

data -- admin.shp (administration area, which includes 5 polygons)

****
when performing shp2tile command, no parameters are set,  and by default the
shapefile is sliced into 2*2+1 shapefiles. With the following layer object
definition, map image is drawn:

LAYER
    NAME "administration"
    GROUP "country"
    STATUS DEFAULT
    TILEINDEX "index"
    TILEITEM "LOCATION"
    TYPE POLYGON
    DEBUG ON
    TRANSPARENCY ALPHA
    CLASS
      NAME "woodland"
      STYLE
        COLOR 204 204 255
        ANTIALIAS TRUE
      END
    END
  END
**********
Second test example:

data -- settlement.shp, which contains 2155664 polygons

****
when performing shp2tile command for this shapefile, I set 10*10, each slice
contians therefore about 21557 polygons. It's also ok with tile4ms and
shptree commands.

hm... seems exciting...

but, with this layer object definition no settlements are drawn :

LAYER
    NAME "Settlement"
    GROUP "settlements"
    STATUS DEFAULT
    TILEINDEX "settlementindex"
    TILEITEM "LOCATION"
    MAXSCALE 100000
    TYPE POLYGON
    DEBUG ON
    TRANSPARENCY ALPHA
    CLASS
      NAME "SM"
      STYLE
        COLOR 153 153 102
        ANTIALIAS TRUE
      END
    END
  END
*****
I have now really no idea where the problems should be.

Steve, any clues?

thanks for your info.

zhonghai

On 5/18/06, Stephen Woodbridge <woodbri at swoodbridge.com> wrote:
>
> Zhonghai Wang wrote:
> > 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
>
> This is likely because you are trying to create 2501 files (50 x 50 + 1)
> and they all half to be open at the same time for this mode so you
> likely ran into a process file handle limit. Also how many point do you
> have in this layer? What is the value of Num_points/2500, this number
> should not be smaller than 8000 - 10000.
>
> > 2. >tile4ms ---- get the tileindex.shx, tileindex.shp and tileindex.dbf
> > files for the Forests_Test.shp, there is still no prj file for
> tileindex.shp
> >  >>>no error messages appear at this step
>
> There are no prj files created. Mapserver does not use them.
>
> > 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.
>
> What version of shp2tile are you using?
>
> woodbri at carto:/data/mdata$ ~/dev/shptools/shp2tile -v
> $Id: shp2tile.c,v 1.13 2005/12/05 22:38:08 woodbri Exp $
>
> If it does not respond with the Id string above you need to upgrade as
> there is a serious crashing bug for point data in the earlier version if
> you are using the -q option. It should work for the row col option, just
> try to decrease the number of tiles.
>
> Also if you do not have something like R x C files in your directory
> then the process failed. For the row col option you can also specify
> --no-write to just get a stats report of how the data is put into the
> tiles.
>
> -Steve
>
> > thanks for any further info.
> >
> > zhonghai
> >
> > On 5/18/06, *Zhonghai Wang* < zhonghaiw at gmail.com
> > <mailto: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
> >     <mailto: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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