[QGIS-Developer] Reg: QgsCoordinateTransform not working on Linux

[Prem Kumar]

Hi Ujaval,

Thanks for your reply. I have made the suitable code changes as you have
suggested but I still see the same behaviour.

In fact, the given code snippet in the email is an extract from my overall
code where proper initialisation and disposing of qgis application object
is followed. The only difference between running the script on windows and
linux is that, Im running the script on linux machine in a python virtual
environment where as windows, running it directly from qgis python
distributable. Some additional information and thanks for the troubleshoot
option.

*Windows:*
OS: Microsoft Windows 10 Enterprise
QGIS: 3.10.10-A Coruña
Python: Python 3.7.0

*Linux: *
OS Kernel: Ubuntu 18.04.3 LTS
QGIS: '3.16.3-Hannover'
Python: Python 3.6.9

-Prem







On Thu, May 27, 2021 at 6:50 PM Ujaval Gandhi <ujaval at spatialthoughts.com>
wrote:

> You are not initializing QGIS in your script. Try adding this at the
> beginning of your script
>
> from qgis.core import QgsApplication
>
> qgs = QgsApplication([], False)
> qgs.initQgis()
>
> [image: Logo] <https://spatialthoughts.com/>
> Ujaval Gandhi
> Spatial Thoughts
> mobile: +91-8095684687
> email: ujaval at spatialthoughts.com
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> Twitter icon] <https://twitter.com/spatialthoughts>
>
>
>
> On Thu, May 27, 2021 at 6:27 PM Prem Kumar <prem.netgis at gmail.com> wrote:
>
>> Hi Team,
>>
>> Just wondering whether I'm missing something or a genuine bug, please
>> advise below.
>>
>> All I am trying is, to take the geometry object in json format whose CRS
>> is in WGS84 (EPSG:4326) and transform the geometry to EPSG:3857 CRS and
>> eventually use it in further processing because rest of the processing is
>> in EPSG:3857 CRS.
>>
>> I have written below code and it works like a charm on Windows 10 but it
>> doesn't transform the geometry on Linux. Please advise if there is anything
>> wrong or missing to add.
>> *Code Snippet for reproducing:*
>>
>> from qgis.PyQt.QtCore import QVariant
>> from shapely.geometry import shape
>> import geojson,json
>> from qgis.core import (QgsGeometry,QgsCoordinateReferenceSystem,QgsCoordinateTransform,QgsProject)
>> from shapely import speedups as sups
>> sups.disable()
>>
>> in_geometry='[{"type": "LineString","coordinates": [[-78.85338577199997,43.85845267000008],[-78.85593885699996,43.857924291000074]]}]'
>> geomjson = json.loads(in_geometry)
>> old_crs = QgsCoordinateReferenceSystem("EPSG:4326")
>> new_crs = QgsCoordinateReferenceSystem("EPSG:3857")
>> xtransform = QgsCoordinateTransform(old_crs, new_crs, QgsProject.instance())
>> for i, g in enumerate(geomjson):
>>     s = json.dumps(g)
>>     g1 = geojson.loads(s)
>>     shapely_geom = shape(g1)
>>     qgs_geom=QgsGeometry.fromWkt(shapely_geom.wkt)
>>     qgs_geom.transform(xtransform)
>>     print (qgs_geom)
>>
>> *Output from Pycharm:*
>> C:\Qgis\apps\Python37\python.exe C:/_WORK/SERVICE/test_transform.py
>> <QgsGeometry: LineString (-8777918.77684544585645199
>> 5443563.52439526654779911, -8778202.97550544328987598
>> 5443481.85537817236036062)>
>>
>> Process finished with exit code 0
>>
>> *Output from Linux terminal:*
>> (gisenv) admin at rd-temp-server:~/gis_service$ python3 test_transform.py
>> Application path not initialized
>> Application path not initialized
>> <QgsGeometry: LineString (-78.85338600000000042 43.85845299999999725,
>> -78.85593900000000644 43.85792399999999702)>
>> (gisenv) admin at rd-temp-server:~/gis_service$
>>
>> Thanks.
>> -Prem
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>
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