Removing sharp curves using ArcPy

Question

I have been trying for some time to find a way to eliminate the exaggerated curves in a contour curve that I usually obtain from line 0. The idea is to obtain a polyline that is more or less faithful to the coast line but that ignores specific irregularities such as, for example, the presence of a breakwater or a dike. Although it is not an excessively complex job, this process is integrated into a tool that I am building and therefore I would like to automate it. For example, if I have the following polyline fragment:

I would like to get roughly the following output:

So far I've gotten away with simplifying the line and then smoothing it out:

arcpy.SimplifyLine_cartography(in_polyline,simp_polyline,"EFFECTIVE_AREA",45,collapsed_point_option='NO_KEEP')
arcpy.SmoothLine_cartography(sim_polyline,smooth_polyline,"PAEK",45)

However, I do not always get the desired output and it depends a lot on the area in which I am. Therefore I have decided to consult you, since I imagine that more than one will have run into a similar problem.

Answer 1

I think the most robust way is deriving medial axis of line buffer:

Vector solution is hard, perhaps consider raster based solution explained here.

Workflow (tools) for raster solution:

arcpy.Buffer_analysis(in_features="ORIGINAL", out_feature_class="in_memory/BUFFER", buffer_distance_or_field="20 Meters", line_side="FULL", line_end_type="FLAT", dissolve_option="NONE", dissolve_field="", method="PLANAR")
arcpy.PolygonToLine_management(in_features="buffer", out_feature_class="in_memory/BORDER", neighbor_option="IDENTIFY_NEIGHBORS")
arcpy.Merge_management(inputs="BORDER;ORIGINAL", output="in_memory/MERGED", field_mappings='LEFT_FID "LEFT_FID" true true false 0 Long 0 0 ,First,#,BORDER,LEFT_FID,-1,-1')
arcpy.Dissolve_management(in_features="MERGED", out_feature_class="in_memory/THREE_LINES", dissolve_field="", statistics_fields="", multi_part="SINGLE_PART", unsplit_lines="DISSOLVE_LINES")
arcpy.SelectLayerByLocation_management(in_layer="THREE_LINES", overlap_type="SHARE_A_LINE_SEGMENT_WITH", select_features="ORIGINAL", search_distance="", selection_type="NEW_SELECTION", invert_spatial_relationship="INVERT")
arcpy.PolygonToRaster_conversion(in_features="buffer", value_field="OBJECTID", out_rasterdataset="in_memory/cost_3", cell_assignment="CELL_CENTER", priority_field="NONE", cellsize="F:\SCRATCH\SCRATCH.gdb\MASK")
arcpy.gp.CostAllocation_sa("THREE_LINES", "cost_3", "F:/SCRATCH/SCRATCH.gdb/ALLOCATION", "", "", "OID", "", "", "", "", "", "", "")

Output of above:

As one can see result is highly dependent on a quality of flat end buffer I used at the beginning - see artefact at eastern end. Perhaps smooth original first. Note it can be done with round buffer, but it is more tricky.

Convert allocation raster to polygons and delete lines on the sides:

RasterToPolygon_conversion(in_raster="ALLOCATION", out_polygon_features="in_memory/POLYGONS", simplify="NO_SIMPLIFY", raster_field="Value", create_multipart_features="SINGLE_OUTER_PART", max_vertices_per_feature="")
PolygonToLine_management(in_features="POLYGONS", out_feature_class="in_memory/LINES", neighbor_option="IDENTIFY_NEIGHBORS")
SelectLayerByAttribute_management(in_layer_or_view="LINES", selection_type="NEW_SELECTION", where_clause='"LEFT_FID" =-1')
DeleteFeatures_management(in_features="LINES")

Output shows original smoothed result line.