[Qgis-user] Map graticules in QGIS

[Alex Mandel]

On 03/11/2013 12:18 AM, Lester Anderson wrote:
> On 11 March 2013 00:54, Alex Mandel <tech_dev at wildintellect.com> wrote:
>
>> On 03/10/2013 03:49 PM, Lester Anderson wrote:
>>> On 10 March 2013 22:22, Alex Mandel <tech_dev at wildintellect.com> wrote:
>>>
>>>> On 03/10/2013 03:13 PM, Lester Anderson wrote:
>>>>
>>>>> Hello,
>>>>>
>>>>> The one major element missing from the otherwise great Quantum GIS, is
>>>>> that
>>>>> of easy setup map graticules. There is a basic way of doing simple
>> ones in
>>>>> the print composer which is fine for geographic (WGS84) or UTM etc type
>>>>> projections, but will not work for conic or stereographic etc.
>>>>>
>>>>> Is there a plugin for doing this work (that is built-in to layout mode
>> in
>>>>> ArcGIS) or is this an upgrade/update that will be available in a new
>>>>> release?
>>>>>
>>>>> Generating a vector grid does not work properly in 1.8.0, and certainly
>>>>> only partially completes a Polar Stereographic layout. There are
>> clearly
>>>>> flaws that need to be addressed. If there is a reliable workaround for
>>>>> this, it would be good to know.
>>>>>
>>>>> Lester
>>>>>
>>>>>
>>>> A workaround is to make the graticule in WGS84 and reproject it to the
>>>> desired end projection. I found that it doesn't curve well so I wrote
>> this
>>>> script to make graticules with a higher points density that projects
>> well.
>>>>
>>>> https://github.com/**wildintellect/pyGraticule<
>> https://github.com/wildintellect/pyGraticule>
>>>>
>>>> I hope to work it into QGIS at a later point, but you can use it
>>>> standalone with python to make what you need, import and reproject.
>>>>
>>>> Thanks,
>>>> Alex
>>>>
>>>>
>>> Hi Alex,
>>>
>>> I have tried the route you suggested. I am working on Antarctic data, so
>>> generated a vector grid for 0-360 in X (at 10 degrees) and latitude (-90
>> to
>>> -60) in 10 degrees. That all worked fine in WGS84. However, reprojecting
>> to
>>> Antarctic Polarstreographic did not project correctly with less than half
>>> the meridians and no latitudes.
>>>
>>> Cheers
>>> Lester
>>>
>>
>> This will probably get stripped from the list but I've attached a shp I
>> made that should be what you need. Let me know if you need me to upload
>> it to server for download.
>>
>> Note projection on the fly has some odd bug that makes 180/-180
>> disappear, I've not spent enough time to figure out what that is.
>>
>> What I did:
>> Used my pyGraticule script modified to go from -90,1
>> Reprojected to Polar EPSG:3031 as a shapefile
>>
>> I'm trying to remember how I did
>> http://geography.ucdavis.edu/image/499
>> If I remember I'll post some more details.
>>
>> Thanks,
>> Alex
>>
>>
>> Hi Alex,
>
> That worked very well. I had a look at the Python script and I note that it
> generates a GeoJSON format file. How do you convert to a shapefile?
>
> Hopefully something along the lines of the script will be built in to QGis,
> the OTF reprojection of somethings does fall over.
>
> Cheers
> Lester
>

I opened it in QGIS, then did a file Save As... shp in the new projection.

I tried re-projecting the geojson to geojson and it didn't render right 
either. So I think I've found a bug in the projection tool or renderer. 
I'll note that it's happened to me with Geotiff too, polar projection 
ends up looking like pacman.

Thanks,
Alex