Problem using Chordal axis

[mymysz]

Hi,

I would love to use the chordal axis tool but I encounter a problem : "for line in centre_lines: UnboundLocalError: local variable 'centre_lines' referenced before assignment"

I don't really understand a single thing about Python... so please help me !

Thank you :)

[AdrianCarreno]

Same issue here. I have Geo Simplification v1.2.0.

Upon examining the error, it seems that the code is catching an exception at chordal_axis_algorithm.py:192, and therefore not declaring the variable centre_lines, and after the code exits the try/except block, it tries to use the variable.

By moving the for line in centre_lines:block into the try, allows the program to finish the tessellation and generate results, but the chordal axis is an empty layer (because it generated an exception).

[vovchykbratyk]

Ran into the same problem on chordal axis. Tried following @AdrianCarreno suggestion along with some pass calls but would not write out the lines.

[Dan-Eli]

@AdrianCarreno @vovchykbratyk @mymysz If you could provide me with a file (shape, Geo Package,...) that is bugging that would be helpful for the bug correction. Inlude also: QGIS version and OS version you are using. Thank you.

[joel-HOME]

Same issue here. QGIS Version:3.28.3-Firenze OS: Mac 12.2.1

bugging file(Roads of Bangkok, Thailand): OUT_TH_BIG_ROADS_POLYS.csv

[Dan-Eli]

Thanks for the the CSV example. Did you got the same following error crash?

QGIS version: 3.28.0-Firenze QGIS code revision: ed3ad0430f3 Qt version: 5.15.3 Python version: 3.9.5 GDAL version: 3.5.2 GEOS version: 3.10.3-CAPI-1.16.1 PROJ version: Rel. 9.1.0, September 1st, 2022 PDAL version: 2.4.3 (git-version: 434757) Algorithm started at: 2023-02-22T22:44:10 Algorithm 'Chordal axis' starting… Input parameters: { 'CORRECTION' : False, 'INPUT' : 'C:/Users/dpilon/Downloads/OUT_TH_BIG_ROADS_POLYS.csv|geometrytype=Polygon|uniqueGeometryType=yes', 'OUTPUT' : 'TEMPORARY_OUTPUT', 'TRIANGLES' : 'TEMPORARY_OUTPUT' }

Results: {'OUTPUT': 'output_0355f165_53d8_4a40_8c90_7da4db1aabcc'} Results: {'OUTPUT': 'output_d667af3f_80e4_4128_8a52_4ad14dabe3db'} Results: {'OUTPUT': 'output_cc9bf4ac_32fd_4980_94a2_d7d8f43275a3'} Traceback (most recent call last): File ".../Roaming/QGIS/QGIS3\profiles\default/python/plugins\geo_sim_processing\chordal_axis_algorithm.py", line 201, in processAlgorithm for line in centre_lines: UnboundLocalError: local variable 'centre_lines' referenced before assignment

Execution failed after 1.67 seconds

[Dan-Eli]

The problem is reproduced here File "C:\Users/dpilon/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\geo_sim_processing\chordal_axis_algorithm.py", line 1325, in adjacent_sides_ref xy = (mid_pnt_side.x, mid_pnt_side.y) AttributeError: 'QgsGeometry' object has no attribute 'x' is caused by the small dynamic value of the coordinates in the file . They are in lat-lon (probably) so between[-180:180], the problem come with the value used with the epsilon when we try to estimate what is 0. Presently it is a fix value set to 0.000001. It needs to be set dynamically or change the logic so not to rely on an epsilon value.

@AdrianCarreno @vovchykbratyk @mymysz @joel-HOME change your projection/EPSG to Web Mercator (3857) or any other projection/EPSG just for the Chordal Axis process and change it back to your original projection/EPSG after and it should work while I work on the problem.

[mymysz]

Now it works perfectly ! Thank you very much