shp2tile question

Eric Shuman erics at AMERI-TITLE.COM
Thu Feb 2 19:44:56 EST 2006


I also have a similar problem. Don, did you come up with a good solution?
I'm still new to mapserver and have not delved into the indexing
capabilities yet. Can someone enlighten me?

Here is my situation:
I have a map set up that displays cadastral data as well as other layers
such as streets and points of interest.  From PHP I query the map by
attribute for a taxlot ID.  The map layer itself is set to the full extent
of the data, and uses the parcel layer multiple times to show the query
results, as well as for other symbology purposes.  When the lot is found the
map zooms to the extent of the results.  The data extent covers an entire
county so the layers are fairly large, and the map takes awhile to draw.

The questions:
In all cases the final extent is pretty small, maybe 1 square mile max.
Should I be tiling my parcels layer with the shp2tile/ogrtindex combo and
then creating a shptree on the resulting index? OR Should I just create a
shptree on the parcels layer as well as all the other layers?  Will the
shptree help when doing an attribute query, or do I need to find a different
solution for speeding up the attribute query?  Any recomendations on how to
speed things up?

In addition I am serving up aerial photos.  I have a 1Gig MrSid, but don't
really want to get into building mapserver from scratch to add the
functionality.  So my though was to convert the SID to 2500 8Meg TIFF's, and
then run a gdaltindex on them, then maybe a shptree on the index. Is this a
sound plan? Other options? Does anyone have experience with the speed
differences of MrSid vs. TIFF?

Thanks for the help!

~Eric Shuman



On Mon, 18 Apr 2005 10:20:23 -0400, Don Deskins <dldeskins at GMAIL.COM> wrote:

>Steve,
>
>Thank you for your reply.
>
>I have experimented with different numbers and after reading a bit
>more, I have discovered that it make no difference (in my case) how I
>divide it up.  As a matter of fact, my application performs SLOWER the
>more files that I have.
>
>What I am trying to do is to display an area with parcels of land.  I
>have two identical layers... one to display all of the parcels and the
>other to only display the selected parcel.  It is extremely slow when
>querying for by parcel id.  Because of this, I need to put the second
>layer (at least) in a database so that the parcelid field can be
>indexed.
>
>Thanks,
>
>Don
>
>On 4/11/05, Stephen Woodbridge <woodbri at swoodbridge.com> wrote:
>> Don,
>>
>> Like I said there is no magic number. If you are most showing all your
>> parcels most of the time then there is not value in having it tiled. One
>> of the MOST important performance issues is to make sure all your *.shp
>> files have a *.qix file.
>>
>> Try a different set of tiling parameters and test it again.
>>
>> Did you have *.qix on you original shapefile? If not go back to that and
>> add one (shptree file.shp) and see how it performs untiled.
>>
>> -Steve
>>
>> Don Deskins wrote:
>> > Bart and Steve,
>> >
>> > My shapefiles are showing up now... thanks!
>> >
>> > Now I have a time problem... It seems to take more time to generate
>> > the image than it did before.  I am checking for errors now.
>> >
>> > Thanks again.
>> >
>> > Don
>> >
>> >
>> > On Apr 11, 2005 3:28 PM, Bart van den Eijnden <bartvde at xs4all.nl> wrote:
>> >
>> >>Hi Don,
>> >>
>> >>check the dbf of your generated tileindex (the LOCATION field). I usually
>> >>use absolute paths in there. Are there absolute or relative paths to the
>> >>files in there?
>> >>
>> >>Also use TYPE POLYGON. Are you zoomed in enough to have your layer showing
>> >>up, since you are using a MAXSCALE setting?
>> >>
>> >>Best regards,
>> >>Bart
>> >>
>> >>On Mon, 11 Apr 2005 15:24:45 -0400, Don Deskins <dldeskins at gmail.com>
>> >>wrote:
>> >>
>> >>
>> >>>Bart (and Steve),
>> >>>
>> >>>Thanks.
>> >>>
>> >>>I have my files created and tried to reference this index in my map file:
>> >>>
>> >>>  ####################################
>> >>>  # parcels
>> >>>  LAYER
>> >>>    NAME 'tileindex'
>> >>>    TYPE TILEINDEX
>> >>>    DATA '/path/to/tileindex'
>> >>>    MAXSCALE 40000
>> >>>  END
>> >>>
>> >>>  LAYER
>> >>>    NAME 'SCAP_Cert2004_ParcelsUTM16M'
>> >>>    STATUS ON
>> >>>    TYPE POLYGON
>> >>>    TILEINDEX '/path/to/tileindex'
>> >>>    #TILEITEM 'LOCATION'
>> >>>    MAXSCALE 40000
>> >>>  END
>> >>>  ####################################
>> >>>
>> >>>I get no error but my shapes are not showing up... do you see a
>> >>>problem with the above map?
>> >>>
>> >>>Don
>> >>>
>> >>>On Apr 11, 2005 2:58 PM, Bart van den Eijnden <bartvde at xs4all.nl> wrote:
>> >>>
>> >>>>Hi,
>> >>>>
>> >>>>It is tile4ms, not tile2ms, probably a typo by Steve.
>> >>>>
>> >>>>It is a Mapserver utility to make a tileindex. Alternatively, you can
>> >>>>also
>> >>>>use ogrtindex for vector layers and gdaltindex for raster layers.
>> >>>>
>> >>>>Best regards,
>> >>>>Bart
>> >>>>
>> >>>
>> >>--
>> >>Using Opera's revolutionary e-mail client: http://www.opera.com/m2/
>> >>
>> >
>> >
>> >
>> > --
>> > Don Deskins
>> >
>>
>>
>
>
>--
>Don Deskins



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