I am experiencing a small screen space offset when using a WMS layer (origin is GeoServer 2.1.4). Looking at the requests from QGIS (1.7.4) to my GeoServer I realised that the aspect ratio between the WIDTH/HEIGHT and the BBOX is different. Calculating the aspect difference back into screen space gives a difference of ~1 pixel - I wonder if it could be the reason for my offset?

Due to devices with non-square pixels it makes sense that the aspect ratio can differ.

But what is the reason for QGIS not enforcing equality between the aspect ratios?

  • 1
    rounding error? – Ian Turton Jun 28 '12 at 12:44
  • Where in the proces do you propose the rounding error? – Chau Jun 28 '12 at 12:58
  • probably in the bounding box as that is a floating point calculation as opposed to screen size (integer pixel count)? – Ian Turton Jun 28 '12 at 14:21

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