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Exposes simplification and smoothing algorithms to expression engine, via: - simplify(): applies Douglas-Peucker geometry simplification - simplify_vw(): applies Visvalingam-Whyatt geometry simplification - smooth(): smoothes a geometry Carto tip: use smooth along with geometry generators to minimise the typical "GIS" noded look of rendered geometries!
13 lines
1.4 KiB
Plaintext
13 lines
1.4 KiB
Plaintext
{
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"name": "smooth",
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"type": "function",
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"description":"Smooths a geometry by adding extra nodes which round off corners in the geometry.",
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"arguments": [ {"arg":"geometry","description":"a geometry"},
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{"arg":"iterations", "optional":true,"description":"number of smoothing iterations to apply. Larger numbers result in smoother but more complex geometries."},
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{"arg":"offset", "optional":true,"description":"value between 0 and 0.5 which controls how tightly the smoothed geometry follow the original geometry. Smaller values result in a tighter smoothing, larger values result in looser smoothing."},
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{"arg":"min_length", "optional":true,"description":"minimum length of segments to apply smoothing to. This parameter can be used to avoid placing excessive additional nodes in shorter segments of the geometry."},
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{"arg":"max_angle", "optional":true,"description":"maximum angle at node for smoothing to be applied (0-180). By lowering the maximum angle intentionally sharp corners in the geometry can be preserved. For instance, a value of 80 degrees will retain right angles in the geometry."} ],
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"examples": [ { "expression":"geom_to_wkt(smooth(geometry:=geom_from_wkt('LineString(0 0, 5 0, 5 5)'),iterations:=1,offset:=0.2,min_length:=-1,max_angle:=180))", "returns":"'LineString (0 0, 4 0, 5 1, 5 5)'"}]
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}
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