Bug report #10003

rendering artifacts while trying to use a custom CRS Ortho projection on Valmiera

Added by Steven Kay over 6 years ago. Updated almost 5 years ago.

Status:Closed
Priority:Low
Assignee:-
Category:Projection Support
Affected QGIS version:2.2.0 Regression?:No
Operating System:Ubuntu Easy fix?:No
Pull Request or Patch supplied:No Resolution:
Crashes QGIS or corrupts data:No Copied to github as #:18493

Description

Spotted some rendering 'artifacts' while trying to use a custom CRS Ortho projection on Valmiera.

My custom CRS is an orthographic projection centered on London :-

+proj=ortho +lat_0=51.45 +lon_0=-1.0 +x_0=0 +y_0=0

As you can see from the enclosed screenshot, there are two types of rendering artifacts...

- 45 degree extensions to the top-left (filled vector layer)
- gradient filled ellipses radiating to (0,0) on the canvas (tisserot indicatrices vector layer)

I suspect that polygons which cross the visible 'horizon' aren't being clipped to the circle, and any vertices on these polygons which are hidden are being set to NaN / infinite / zero value?

Polygons, lines and points which are fully beyond the horizon remain hidden.

40.png - example screenshot (609 KB) Steven Kay, 2014-04-06 01:19 PM

History

#1 Updated by J├╝rgen Fischer about 6 years ago

  • Target version changed from Version 2.2 to Future Release - Lower Priority

#2 Updated by Steven Kay almost 5 years ago

  • Status changed from Open to Closed

I've closed this, there's a plugin called "Clip to Hemisphere" which clips a vector layer to the hemispherical edge from a given center point... this fixes the rendering issues.

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