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Heat Maps: Moving contour lines and artefacts

Posted By Torsten Thiele 5 Years Ago
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Torsten Thiele
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Two observations when using heat maps. Both can be reproduced with Example "Heat Map - Contour".
  1. When switching "Show Fill" between on and off, displayed contour lines are moving, although they should remain unchanged. This appears to be a bug.
  2. When turning on "Interpolate image", there are artefacts in the coloring along the borders of the heat map, looking like buckles. Maybe this is due to improper interpolation at the borders.


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Torsten Thiele
Posted 5 Years Ago
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Will these bugs be fixed?

Best regards,
Torsten



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Posted 5 Years Ago
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Hi Torsten,

We finished reviewing the two issues above and they do not appear to be a bug:

1.When switching "Show Fill" between on and off, displayed contour lines are moving, although they should remain unchanged. This appears to be a bug.
It is actually by design. The idea between the offset when turning the fill on and off is the treatment of where the value specified by the grid data cell lies.
1.1 In the case of enabled fill the value is treated as positioned in the center point of the grid cell. Contour lines, in this case are constructed by taking the intersections of the horizontal and vertical grid center cells lines with the specified elevation values. In other words if you have a grid of 2x2 starting at origin [0, 0] with step [1, 1] then the image will span the range [0, 2] along x and y axes and contour lines are going to be created based on the intersections of the lines [0.5, 0.5] - [1.5, 0.5], [0.5, 1.5] - [1.5, 0.5] horizontal and [0.5, 0.5] - [0.5, 1.5], [1.5, 0.5] - [1.5, 1.5] vertical.

2.2 In the case where there is no grid filling the contour lines are generated by using the "normal" grid lines - [0.0, 0.0] - [2.0, 0.0], [0.0, 1.0] - [2.0, 1.0], [0.0, 2.0] - [2.0, 2.0] horizontally and [0.0, 0.0] - [0.0, 2], [1.0, 0.0] - [1.0, 2.0], [2.0, 0.0] - [2.0, 2.0] vertically.

2. When turning on "Interpolate image", there are artifacts in the coloring along the borders of the heat map, looking like buckles. Maybe this is due to improper interpolation at the borders.
This is actually caused by the graphics image interpolation - we will a clipping on top of that to rectify this. We'll keep you posted.

Hope this helps - let us know if you have any questions or comments.



Best Regards,
Nevron Support Team





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