Hi,
I have downloaded the Land Cover and Population Data for Canada and converted them first to ESRI ASCII and then to ESRI grid files. Next, I need to project the grid files, as it is missing spatial reference now. I tried several projections (including Robinson, WGS84 and NAD 1983), but none seems to project the grid files.
Which projection do I have to choose in order to display the data correctly? If there's any way to do this in DIVA-GIS before exporting the data to ESRI ASCII files, that would help too.
Thanks for your help!
Anne
Re: projections
But hello, no matter what GIS program you use, DIVA or other, you should always take note of the original projection used for the data you import. You don't have to reproject unless you really need to have a particular projection, e.g. to enable comparision or overlay with other data you may have. Just use the same parameters as in the original.
For Canada the projection could be something like Lambert Conformal Conic with standard parallels at 49 and 77 and central meridian at -95, ellipsoid GRS80. Datum does not matter much on a scale like this, but WGS84 (which also sets the ellipsoid to GRS80) is probably what you should enter if asked. But check the with the original source.
Unprojected data (geographical coordinates) in the case of Canada does not make sense because of the the large differences in horizontal resolution between north and south if data is presented in degrees-minutes-seconds format. So go back to the source and look for the metadata. Almost certainly there was some projection information associated with the Land Cover and Population data you imported.
Projections
Hi there,
Which program are you using to assign projections or coordinate systems and how exactly are you doing it? ArcGIS for example has a number of different ways of projecting data. The safest is to use Data Management Tools> Projections and Transformations. If using this only use it in Arc Catalog or you may get error messages. Hope this helps.