[Qgis-user] Trouble projecting on the fly

[Ramon Andiñach]

On using OTF...
> On 24 Feb 2015, at 14:06, Sharon Selvaggio <ssitalian at comcast.net> wrote:
> 
> Thanks to both, but I'm still having trouble.  I must be doing something wrong.
> 
> These are the steps I took after reading the advice from both of you.
> 
> I start by setting my project CRS.

And make sure OTF is on. 

> Then I click Layer, add layer, add vector layer.

This layer should have a CRS assigned to it and QGIS will display it- transforming it on the fly into the project's CRS.

Repeat for the next layer. 

That should be it. No Save As needed. 

> But when I do this with files that have originated from two different sources with different native projections (or no projection?) they still do not align.

Different sources or different layer CRS shouldn't matter.

If layers don't line up, then this implies that:
* one of the layers has coordinates that are wrong (or for a raster a georeferencing problem),[1]
* one of the layers has a CRS that is incorrect (one of my data providers has a tab file that is routinely picked up as the wrong CRS - the CRS provided is ambiguous so not really QGIS's fault)
* the underlying database doesn't understand the CRS you're using properly. This also implies either something really new like the Croation grid problem mentioned the other day or something quite old (e.g. AGD66 - which now seems to work :),  or just plain uncommon (yes AGD66 is still used).

There is an option mentioned previously so that you can set how QGIS handles layers that it can't tell what the CRS is. 

If you can point us at the files you're using - or excerpts from them - then we might be able to understand where the problem is better. 

-ramon. 

1. On a side note. Do not use the Google maps/satellite images to check if your layers are in the right place unless you understand the gotchas in using that service.