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.dbf files 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 <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED] > 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.
