I'm looking for a way to create a polygon (grey area in picture) behind another polygon (green), just like a shadow from a point / another polygon (blue).
To make it clearer here's what I mean:
It seems obvious to create a 100 m buffer around the green polygon, but what would be the next step? If it's only one polygon, I'd cut it manually, but it's +100.
I'm using ArcMap Basic licence without any extensions. And no coding skills.
Yes it is much more straightforward with advanced license using near, erase, points to line etc. tools. Anyway the workflow below will work with basic license and it is a good candidate for model builder. Shouldn't be hard to shuffle through 100 polygons. It honors selection:
# find script to convert all building vertces to points
arcpy.FeatureVerticesToPoints_management(in_features="BUILDING", out_feature_class="C:/SCRATCH/ALL_POINTS.shp", point_location="ALL")
arcpy.AddGeometryAttributes_management(Input_Features="VIEW_POINT", Geometry_Properties="POINT_X_Y_Z_M", Length_Unit="", Area_Unit="", Coordinate_System="")
arcpy.SpatialJoin_analysis(target_features="ALL_POINTS", join_features="VIEW_POINT", out_feature_class="C:/SCRATCH/SJ.shp", join_operation="JOIN_ONE_TO_ONE", join_type="KEEP_ALL", field_mapping='GISBUILDIN "GISBUILDIN" true true false 10 Long 0 10 ,First,#,ALL_POINTS,GISBUILDIN,-1,-1;ORIG_FID "ORIG_FID" true true false 10 Long 0 10 ,First,#,ALL_POINTS,ORIG_FID,-1,-1;GISBUILDIN_1 "GISBUILDIN_1" true true false 10 Long 0 10 ,First,#,VIEW_POINT,GISBUILDIN,-1,-1;POINT_X "POINT_X" true true false 19 Double 0 0 ,First,#,VIEW_POINT,POINT_X,-1,-1;POINT_Y "POINT_Y" true true false 19 Double 0 0 ,First,#,VIEW_POINT,POINT_Y,-1,-1', match_option="CLOSEST", search_radius="", distance_field_name="Distance")
# add fields to store view points coordinates
arcpy.AddField_management(in_table="SJ", field_name="NEW_X", field_type="DOUBLE", field_precision="", field_scale="", field_length="", field_alias="", field_is_nullable="NULLABLE", field_is_required="NON_REQUIRED", field_domain="")
arcpy.AddField_management(in_table="SJ", field_name="NEW_Y", field_type="DOUBLE", field_precision="", field_scale="", field_length="", field_alias="", field_is_nullable="NULLABLE", field_is_required="NON_REQUIRED", field_domain="")
arcpy.CalculateField_management(in_table="SJ", field="NEW_X", expression="[POINT_X]", expression_type="VB", code_block="")
arcpy.CalculateField_management(in_table="SJ", field="NEW_Y", expression="[POINT_Y]", expression_type="VB", code_block="")
# find end points coordinates and extend future line to 1000 m from view point
arcpy.AddGeometryAttributes_management(Input_Features="SJ", Geometry_Properties="POINT_X_Y_Z_M", Length_Unit="", Area_Unit="", Coordinate_System="")
arcpy.CalculateField_management(in_table="SJ", field="POINT_X", expression="[NEW_X]+( [POINT_X]- [NEW_X])/ [Distance]*1000", expression_type="VB", code_block="")
arcpy.CalculateField_management(in_table="SJ", field="POINT_Y", expression="[NEW_Y]+( [POINT_Y]- [NEW_Y])/ [Distance]*1000", expression_type="VB", code_block="")
arcpy.XYToLine_management(in_table="SJ", out_featureclass="C:/SCRATCH/RAYS.shp", startx_field="NEW_X", starty_field="NEW_Y", endx_field="POINT_X", endy_field="POINT_Y", line_type="GEODESIC", id_field="", spatial_reference="PROJCS['NZGD_2000_New_Zealand_Transverse_Mercator',GEOGCS['GCS_NZGD_2000',DATUM['D_NZGD_2000',SPHEROID['GRS_1980',6378137.0,298.257222101]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]],PROJECTION['Transverse_Mercator'],PARAMETER['False_Easting',1600000.0],PARAMETER['False_Northing',10000000.0],PARAMETER['Central_Meridian',173.0],PARAMETER['Scale_Factor',0.9996],PARAMETER['Latitude_Of_Origin',0.0],UNIT['Meter',1.0]];-4020900 1900 450445547.391054;-100000 10000;-100000 10000;0.001;0.001;0.001;IsHighPrecision")
# buffer (with dissolve) 1000 m rays and create their convex hull to produce sector
arcpy.Buffer_analysis(in_features="RAYS", out_feature_class="C:/SCRATCH/BUFFER.shp", buffer_distance_or_field="1 Meters", line_side="FULL", line_end_type="ROUND", dissolve_option="ALL", dissolve_field="", method="PLANAR")
# line below is the only "arcpy" expression
arcpy.CalculateField_management(in_table="BUFFER", field="Shape", expression="!Shape!.convexHull()", expression_type="PYTHON_9.3", code_block="")
arcpy.Buffer_analysis(in_features="BUFFER", out_feature_class="C:/SCRATCH/SECTOR.shp", buffer_distance_or_field="-1 Meters", line_side="FULL", line_end_type="ROUND", dissolve_option="NONE", dissolve_field="", method="PLANAR")
# intersect bulding buffer with sector and find shadow
arcpy.Intersect_analysis(in_features="BUFF_50M #;SECTOR #", out_feature_class="C:/SCRATCH/ISECT.shp", join_attributes="ALL", cluster_tolerance="-1 Unknown", output_type="INPUT")
arcpy.Union_analysis(in_features="ISECT #;BUILDING #", out_feature_class="C:/SCRATCH/SCRATCH.gdb/ISECT_Union", join_attributes="ALL", cluster_tolerance="", gaps="GAPS")
arcpy.SelectLayerByLocation_management(in_layer="ISECT_Union", overlap_type="ARE_IDENTICAL_TO", select_features="BUILDING", search_distance="", selection_type="NEW_SELECTION", invert_spatial_relationship="INVERT")
arcpy.MultipartToSinglepart_management(in_features="ISECT_Union", out_feature_class="C:/SCRATCH/SCRATCH.gdb/SPARTS")
arcpy.Sort_management(in_dataset="SPARTS", out_dataset="C:/SCRATCH/SORTED.shp", sort_field="Shape_Area DESCENDING", spatial_sort_method="UR")
arcpy.SelectLayerByAttribute_management(in_layer_or_view="SORTED", selection_type="NEW_SELECTION", where_clause='"FID" >0')
arcpy.DeleteFeatures_management(in_features="SORTED")
