[FEATURE] New simplify + smoothing expression functions
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!
"description":"Simplifies a geometry by removing nodes using a distance based threshold (ie, the Douglas Peucker algorithm). The algorithm preserves large deviations in geometries and reduces the number of vertices in nearly straight segments.",
"description":"Simplifies a geometry by removing nodes using an area based threshold (ie, the Visvalingam-Whyatt algorithm). The algorithm removes vertices which create small areas in geometries, eg narrow spikes or nearly straight segments.",
{"arg":"iterations", "optional":true,"description":"number of smoothing iterations to apply. Larger numbers result in smoother but more complex geometries."},
{"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."},
{"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."},
{"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."} ],
