Re: [udig-users] WGS84 problem

[Jody Garnett <Jody.Garnett@xxxxxxxxxxxx>]

Hi Andrea:

It sounded like the data was multiplied by 1,000,000 - in this case I would expect the coordinate range to be +/-180,000,000  and +- 90,000,000 in order to correctly describe this.

I have run into this once before where information for a region was measured in cm (so the data could be recorded in integers rather than floating point numbers).  Once we had correctly described this in the CRS - and after that everything rendered fine.

You can use a function as part of each and every symbolizer in order to manipulate the geometry; this would allow you to preprocess the data if you desired (in this case dividing by 1,000,000).

Jody

On 09/09/2011, at 5:13 PM, andrea antonello wrote:

> Still I am not convinced Jody. In my understanding a geographic
> reference system lives in the ellipsoid space. Therefore it doesn't
> make sense to build it with coordinates that get outside +-180, +-90.
> If we are talking about projected systems, ok, you do whatever you
> want, but not in the geographic space.
> So, I guess there is no way to handle that in the prj file.
> 
> Jody, isn't there a way to use some style geometry function to apply a
> transform to the geometry?
> 
> Andrea
> 
> 
> On Thu, Sep 8, 2011 at 11:24 PM, Jody Garnett <jody.garnett@xxxxxxxxx> wrote:
>> The correct solution here is to define a custom CRS that actually matches
>> the data; the uDig environment has the tools to do this; what is needed is a
>> bit of research / reading.
>> I do not think there is a need to look functions; the data is *correct* - we
>> just need to have the proper description so that uDig can use it.
>> Did you want to mess with the unit setting a bit? I do not have any sample
>> data so I feel a bit like I am making suggestions from the side line.
>> There is some scary background reading
>> here: http://docs.geotools.org/latest/userguide/library/referencing/internal.html
>> But really all the same settings are available from WKT; it would be easier
>> to read the standard or ask the person who gave you the data for the correct
>> WTK (or ".prj" file).
>> --
>> Jody Garnett
>> 
>> On Thursday, 8 September 2011 at 9:39 PM, andrea antonello wrote:
>> 
>> While scaling a projected system might be useful, I don't think that
>> it makes much (physical) sense to scale a geographic coordinate
>> system.
>> So I assume there is no way to scale the WGS84 system (but I might be
>> wrong) from the projection definition.
>> 
>> Perhaps through the new sld functions that geotools added lately? But
>> I would not know how. Jody?
>> 
>> Ciao,
>> Andrea
>> 
>> 
>> 
>> On Wed, Sep 7, 2011 at 2:13 PM, Jody Garnett <jody.garnett@xxxxxxxxx> wrote:
>> 
>> You can define your own custom "CRS" for the layer.
>> 1. right click on the layer (after you have loaded it)
>> 2. choose the CRS property page
>> 3. select a good normal WGS84 starting point (such as "EPSG:4326") it should
>> look something like this:
>> GEOGCS["WGS 84",
>>   DATUM["World Geodetic System 1984",
>>     SPHEROID["WGS 84", 6378137.0, 298.257223563, AUTHORITY["EPSG","7030"]],
>>     AUTHORITY["EPSG","6326"]],
>>   PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]],
>>   UNIT["degree", 0.017453292519943295],
>>   AXIS["Geodetic longitude", EAST],
>>   AXIS["Geodetic latitude", NORTH],
>>   AUTHORITY["EPSG","4326"]]
>> 4. Switch to the tab that lets you define your own
>> 5. Modify the "well known text" description so that the axis information is
>> different (and matches your data)
>> I hunted down some examples for you here:
>> - http://docs.geoserver.org/latest/en/user/advanced/crshandling/customcrs.html
>> it looks like the "scale factor" may actually just allow you to do what you
>> want? The "Well known text" is actually a standard defined by the OGC - so
>> if you really get stuck you can read the standard?
>> --
>> Jody Garnett
>> 
>> On Wednesday, 7 September 2011 at 5:38 PM, Mirza Hadzic wrote:
>> 
>> Hello, I have problem with dataset (MySQL) which is stored in integer WGS84
>> coords, so it is multiplied by 1 million. For example coordinate 24.002525
>> is stored as 24002525 (same rule for both coords). Is there any magic in
>> uDig to display this?
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