[Geoserver-devel] (no subject)

john_h_harris · June 4, 2004, 4:41pm

Hi,

I'm a little confused about viewing shape files that have been loaded into
the server. I have loeaded a shape file (the main roads of california),
and it gets looaded without incidence. How, at this point do I view it?
I looked at the demo with the bc roads and was confused by the boundingbox
servlet parameter

example:
http://nebulous.nceas.ucsb.edu:8070/geoserver/wms?request=GetMap&layers=topp:bc_roads&bbox=489153,5433000,529000,5460816&width=1000&height=200&srs=EPSG:27354&styles=normal&Format=image/png
* what coordinate system do 489153,5433000,529000,5460816 refer to?

It would seem to me that if the info.xml file describes the shapefile in
geocoordinates (lat/long) then the query should be in geocoordiantes also
-- I'm probably missing something simple here.

So, as I was saying I loaded up the california roads without a hitch, but
I'm not sure what boundingbox query prarmeters I should submit to the
servlet -- I tried some abitrary ones an got completly white png's. Here
are some example queries that I issued:

http://nebulous.nceas.ucsb.edu:8070/geoserver/wms?request=GetMap&layers=topp:major_roads_unprojected&bbox=4891,5433000,529,5460816&width=200&height=200&srs=EPSG:27354&styles=normal&Format=image/png
http://nebulous.nceas.ucsb.edu:8070/geoserver/wms?request=GetMap&layers=topp:major_roads_unprojected&bbox=-100,100,-100,100&width=200&height=200&srs=EPSG:27354&styles=normal&Format=image/png

(both bame up white (blank) images)

my info.xml files are like:

####################### start info #######################################
<featureType datastore = "usaroads" >
<name>major_roads_unprojected</name>

<SRS>27354</SRS>
<title>test usa roads</title>
<abstract>This is some road features USA</abstract>
<numDecimals value = "0" />
<keywords>USA, road, </keywords>
<latLonBoundingBox dynamic = "false" miny = "32.54218933792563" maxy =
"42.00256500076555" maxx = "-114.4803222939074" minx =
"-124.26521346951216" />

<styles default = "normal" />
</featureType>

####################### end info #######################################

if interested I put the shp file and associated dbf etc at:
http://nebulous.nceas.ucsb.edu/harris/ca_road_shape.tgz

thanks for your help. John

Chris_Holmes1 · June 4, 2004, 5:57pm

Quoting harris@anonymised.com:

Hi,

I'm a little confused about viewing shape files that have been loaded
into
the server. I have loeaded a shape file (the main roads of
california),
and it gets looaded without incidence. How, at this point do I view
it?
I looked at the demo with the bc roads and was confused by the
boundingbox
servlet parameter

example:

http://nebulous.nceas.ucsb.edu:8070/geoserver/wms?request=GetMap&layers=topp:bc_roads&bbox=489153,5433000,529000,5460816&width=1000&height=200&srs=EPSG:27354&styles=normal&Format=image/png

* what coordinate system do 489153,5433000,529000,5460816 refer to?

It refers to the coordinate system specified in srs (spatial reference
system) parameter - EPSG:27354. Granted that parameter is fairly
ignored, as we have yet to implement reprojection, so the only valid
epsg is the one that the data is stored in (but I don't think we raise
an exception for requesting the wrong srs yet).

It would seem to me that if the info.xml file describes the shapefile
in
geocoordinates (lat/long) then the query should be in geocoordiantes
also
-- I'm probably missing something simple here.

No, you're right, the query should be in geocoordinates. For the sample
file the coordinates aren't in geocoordinates. I'm actually trying to
find a second good sample file, that is in lat/long and that contains
polygons instead of lines. If anyone has a nice small one, preferably
with a string as at least one of the attributes, that is of the real
world, then send it along to me.

So, as I was saying I loaded up the california roads without a hitch,
but
I'm not sure what boundingbox query prarmeters I should submit to the
servlet -- I tried some abitrary ones an got completly white png's.

If the bounding box for lat/long for you info.xml file then the bbox
param should be: BBOX=-124.26521347,32.54218934,-114.48032229,42.002565

And actually, I just tested it out, thanks a ton for having a server
available on the internet. This seemed to work for me:

http://nebulous.nceas.ucsb.edu:8070/geoserver/wms?request=GetMap&layers=topp:major_roads_unprojected&bbox=-124.26521347,32.54218934,-114.48032229,42.002565&width=200&height=200&srs=EPSG:27354&styles=normal&Format=image/png

The best way to figure out the bbox to use is by issueing a GetFeature
request:
http://nebulous.nceas.ucsb.edu:8070/geoserver/wfs?request=getFeature&typename=topp:major_roads_unprojected
And the boundedBy element for the collection will have a Box, which is
the limits of the data set. Just use that box, in the same order. If
you copy and paste you just need to change the middle space to a comma.

And I need to make a tutorial on how to do this, add a shapefile and
visualize the data, as I've answered this too many times You're
right in asking though, as we don't document this well anywhere, and
it's one of the most common operations.

best regards,

Chris

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