[Qgis-user] Coordinate transform

[Micha Silver]

David J. Bakeman wrote:

> Micha Silver wrote:
>> David J. Bakeman wrote:
>>
>>> I have some shape files that are in seconds rather than decimal
>> I'm not sure what you mean here. A shapefile is not "in seconds" or 
>> "decimal degrees". The geometry part (*.shp) is a binary 
>> representation of X-Y coordinates, as simple numbers. If the 
>> shapefile also has a *.prj file, then that should contain its 
>> projection information.
>> If you have attribute columns (in the *.dbf part of the shapefile) 
>> with X-Y coordinates, then you can format these columns any way you 
>> like using, for example, Openoffice Calc. But this will *have no 
>> effect* on the geographic location of the features in the shapefile.
>> So, the important question is: do the shapefiles overlay correctly? 
>> If not, then you need to reproject one shapefile to the projection of 
>> the others.
>> Hope that's clear...
> Sorry I didn't make myself clearer.  The shapefiles are missing the 
> prj files and the coordinates of the geometry are in seconds for 
> example 72.5 34.5 would be 261000.0 124200.0.  I can write a quick 
> program to convert since it's a simple /3600 but it seemed like I 
> should be able to have qgis do it for me if I could figure out the 
> correct proj specification.  I have used the transformation plugin in 
> the meantime to scale the data by 1/3600.
>
That will be a first for me! I've never seen LON/LAT coordinates 
specified in seconds.
If you're lacking a *.prj then you will have to know in advance what CRS 
these shapefiles are in. Again, if you display them by assuming 
everything is in Lon/Lat WGS84, do they overlay correctly?

-- 
Micha Silver
Arava Development Co. +972-52-3665918
http://www.surfaces.co.il