[Gvsig_english] Reprojection Roma40-Gauss Boaga to WGS84

[Cristina Bedoya]

Hi Michele,

The steps you need to do for reprojecting are:

1. Open gvSIG and create new View

2. Go to the properties of the View and verify that de units of measure 
and map are in meters and that the current projection is the EPSG:3003 
(MonteMario/Italyzone1)

3. Open the View and add the layer "Iglesias_3003.shp"

4. Then, open the geoprocess of reprojection. And complete:
    - The layer of entry must be: "Iglesias_3003.shp"
    - Current projection must appear: EPSG:3003
    - Destination projection you must:
        - Select RS of the layer type EPSG
        - Select EPSG: 4326 (WGS84)
        - Select the EPSG transformation and then select the button below.
        - Select the transformation with code 1169 or 1662 (Sardinia) 
and Finish.

5. Save the output layer (Iglesias_4326_transf1169.shp) and Accept. (The 
new layer should not be charged in the same View because it's in a 
different RS, developers are already aware of this problem to solve in 
future versions)

6. Then creates a new View and open the properties, select EPSG:4326 as 
a projection of the View.

7. Open the View and load the new layer (Iglesias_4326_transf1169.shp) 
and the comparing layer (Iglesias_4326.shp)

8. Using the tool for measuring distances of gvSIG, you'll see that the 
layers ara far around 5 meters.

To make sure that the transformation made by gvSIG is correct, we've 
compared the transformed layer (Iglesias_4326_transf1169.shp) with some 
WMS services and far around 50 meters.

Unfortunately we've not found any WFS service in the Sardinia area in 
EPSG:4326 to compare the results, if you know a WFS service, you might 
indicate us.

I hope you solved your problem with this steps, if not, please tell us 
about what operating system are you working, what version of gvSIG + 
extensions are you using and if you're comparing the result layer with 
WFS or WMS service, tell us the URL.

Greetings,

Cris




Michele Beneventi wrote:
> Hi Cris,
> first of all thanks for your kind answer.
> I attach here two layers: one of them is the one in EPSG:3003, while 
> the other is the one in EPSG:4326 (this second is the comparing 
> layer). I've found that the reprojection geoprocess makes a mistake of 
> about 150 meters while using the EPSG transformation coding 1662.
> Thanks a lot, I'll wait for your answer.
>
> Michele
>
>   
>
> On Tue, Aug 26, 2008 at 2:05 PM, Cristina Bedoya <bedoya_cri at gva.es 
> <mailto:bedoya_cri at gva.es>> wrote:
>
>     Hi Michele,
>
>     To help, we need more information, if you want, you can send to us
>     the layer that you are transformating (RS "Roma40 - Gauss Boaga"
>     (EPSG: 3003)) and the layer with which you are comparing the data
>     processed.
>
>     Greetings,
>
>     Cris
>
>
>
>
>     Michele Beneventi wrote:
>
>         Hi list,
>         I have a problem concerning the geoprocess of "reprojection".
>         I've had to reproject a polygonal layer from the RS "Roma40 -
>         Gauss Boaga" (EPSG:3003) to the RS "WGS84" (EPSG:4326): for
>         this I've used the geoprocess of "reprojection" both with the
>         transformation "Monte Mario to WGS84 (1)" (EPSG: 1169) and
>         with the transformation "Monte Mario to WGS84 (2)" (EPSG:
>         1662), which are peculiar for the region of Sardinia.
>         Unfortunately the results obtained have shown to be quite bad:
>         actually the mean error is around 90 m. Am I making a mistake
>         with the settings of the geoprocess, or some other mistake?
>
>         Thanks a lot, hope to read from you soon.
>
>         -- 
>         Michele Beneventi
>
>         ------------------------------------------------------------------------
>
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-- 
Cristina Bedoya Pellicé
Proyecto gvSIG
Conselleria de Infraestructuras y Transportes (GVA).
Valencia (Spain)