[Qgis-user] Generate Text Labels for USA National Map?

[Neumann, Andreas]

Hi Jeshua, 

If your want to use the label positions in an iOS app, it might be more
useful to use the PAL label placement algorithm that is used in QGIS to
place the labels dynamically in your iOS app? 

Not sure if the licence would be compatible though. iOS is quite
problematic in combination with OpenSource software. 

Andreas 

On 2017-07-05 23:41, Jeshua Lacock wrote:

>> On Jul 5, 2017, at 2:32 AM, Bernhard Ströbl <bernhard.stroebl at jena.de> wrote:
>> 
>> - I assume you want to have QGIS create label texts for all your data in one go.
> 
> Hi Bernhard,
> 
> That would be ideal.
> 
>> If that is the case this is a misunderstanding of what labels are (in QGIS): QGIS creates (and places) the labels at run-time for the map extract currently on display. Labels thus are no features of their own (GIS only knows points/lines/polygons) but a way to display GIS features (like e.g. color, outline etc.)
> 
> I was afraid that might be the case. :'(
> 
>> - This means the labels are valid for this particular map extract in this particular scale. E.g. imagine a lake (= one polygon) that expands on two map extracts, it will be labeled in both => one feature, two labels
> 
> Understood. I was thinking of generating text at say 4 different scales.
> 
>> - Thus the label text is only within QGIS, export may be possible with dxf-export
> 
> Is it possible to script or automate setting the view extents and exporting?
> 
>> - IMHO it doesn't make sense to try to use the labels outside of QGIS; what is your intended final result? Which software are you planning to use for creating your final result?
> 
> Initially it will be a custom iOS app (with planned android and possibly desktop computer versions). I might offer printed hard copies too at some point.
> 
>> - There will be map extracts with "many" labels (city centres) and map extracts with "few" labels (boondocks).
> 
> Yes, that is why I was looking for something that already can deal with crowded text versus re-inventing the wheel.
> 
>> - QGIS can prevent overlapping labels; in placement you can assign a priority to the labels of this layer (so e.g. rivers are always labeled whereas streets only if not in conflict with rivers)
> 
> Nice.
> 
>> - The rule based labelling works _within_ a layer; a rule is a logical statement about the feature to be labeled. The logic can be based on the feature's attribute values or geometry (e.g. label only lakes larger than x)
> 
> So essentially, I would want all the text on one layer - so point text doesn't overlap with say road or river text, correct?
> 
>> - points are vector features, too, so there is no real difference between labelling points, lines or polygons.
> 
> Great.
> 
>> - Be sure to have read the doc: http://docs.qgis.org/2.14/en/docs/user_manual/working_with_vector/vector_properties.html#labels-menu#
> 
> Thanks for the link and help!
> 
> Best,
> 
> Jeshua Lacock
> Founder/Engineer
> <3DTOPO.com>
> GlassPrinted.com
> 
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