[Qgis-developer] Announce QTiles plugin

[Larry Shaffer]

Hi Math,

On Sun, Dec 30, 2012 at 8:47 PM, Mathieu Pellerin <nirvn.asia at gmail.com> wrote:
> Alex, alright, should have looked at the source code before asking something
> that could be answered quite easily. :)
>
> Few comments and observations after playing with the plugin this morning:
> - QTiles currently renders tiles without applying antialiasing, resulting in
> jagged lines. IMO, disabling antialiasing should be optional, maybe through
> a checkbox in the rendering option window. I've enabled antialiasing by
> adding painter.setRenderHint(QPainter.Antialiasing) below line 167 in
> titlingthread.py
> - The tile background color is hardcoded to be white (line 165,
> titlingthread.py); it might be better to take the background color from the
> project's background color setting? The project I used to test out QTiles
> has a gray background color set through the project settings, and the QTiles
> white background got me going "huh?" for a minute :)
> - As it stands, the labelling rendering is kind of a mess. I understand this
> isn't something that can be fixed at the QTiles level. Might be worth
> coordinating with Larry Shafter to see whether there are quick fixes that
> could be applied to improve things.

I believe a fix for this is to implement this suggested feature (see [0]):

"Add option to have boundaries of map canvas's current extent act as
obstacles to labels (suggested by Tim Sutton)"

Starting in January, I will be focusing on labeling fixes and features
for 2.0, and this is one of the items I think should make it into that
release, especially when it comes to the benefits for tiling. PAL
offers the ability to have features act as obstacles, which should
allow such a function to be implemented with extent-based temporary
features, with a user-defined buffer distance towards the interior of
the rendering.

Another approach is to shrink the extent rect that is used to clip the
temporary geometries sent to PAL. That may result in less labels (not
tested, though).

With the advent of QTiles, and assuming generators for other formats
(mbtiles? [1]) maybe be forthcoming, I will look at implementing this
as soon as possible.

Regards,

Larry

[0] http://hub.qgis.org/wiki/quantum-gis/New_Labeling_changes_and_roadmap
[1] http://mapbox.com/developers/mbtiles/


> - To take care of some of the label cut-off, would it be possible for you to
> not only render the 256x256 tile, but instead do something like this: render
> a 3 x 3 matrix of 256 x 256 tiles, and save only the central 256 x 256
> region as the PNG tile. It wouldn't take care of all label issues, but it'd
> help reduce it.
> - One other thing that could be done at the QTiles level is to warn users
> when it detects that polygon layer(s) are using "most problematic" labelling
> settings (i.e. I'm thinking here of relying on centroid of visible polygon
> centroid, which results in labels duplicated many, many times for each tiles
> with big polygons, such as provincial / district boundaries)
>
> Other than that, I'm loving it more and more ;)
>
> Math
>
>
>
> On Mon, Dec 31, 2012 at 8:46 AM, Mathieu Pellerin <nirvn.asia at gmail.com>
> wrote:
>>
>> This is probably the best gift given out this christmas : )
>>
>> Alexander, quick question, does QTiles render the tiles in the CRS defined
>> by the project, or does it automatically switches to the Google Mercator?
>>
>> Best,
>>
>> Math
>>
>>
>> On Wed, Dec 26, 2012 at 9:24 PM, G. Allegri <giohappy at gmail.com> wrote:
>>>
>>> Wow, thanks for this very useful Christmas gift!
>>> I'm gonna test it next days for a real application ;-)
>>>
>>> giovanni
>>>
>>> Sent from Nexus
>>>
>>> Il giorno 26/dic/2012 14:25, "Alexander Bruy" <alexander.bruy at gmail.com>
>>> ha scritto:
>>>>
>>>> Hi all and sorry for cross-posting,
>>>>
>>>> we (NextGIS) are pleased to announce QTiles plugin for QGIS.
>>>>
>>>> QTiles designed to generate raster tiles from QGIS projects according
>>>> to the Slippy Map specification [0] and supports two output types:
>>>> directory and ZIP-archive.
>>>>
>>>> You can get plugin from official repo (don't forget to enable
>>>> experimental plugins). Comments and bugreports are welcome.
>>>>
>>>> Merry Christmas and happy New Year!
>>>>
>>>> [0] http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
>>>>
>>>> --
>>>> Alexander Bruy
>>>> _______________________________________________
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>>>> http://lists.osgeo.org/mailman/listinfo/qgis-developer
>>>
>>>
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>>
>
>
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