Vector Data Analysis Chapter 10

Introduction  Varies with discipline  Raster vs vector ongoing question

Buffering  Proximity  Buffer points, lines, polygons  Can have varied buffer based on data  Examples  Rings  Dissolved buffers  Analysis technique

Map Overlay  Map overlay combines the geometry and attributes of two feature maps to create the output.  Input and overlay.  Must be same coordinate system and zone, same datum.  Multiple combinations as a process.

Feature Type and Map Overlay  Point-in-polygon  Line-in-polygon  Polygon-on-polygon

Map Overlay Methods  Our old friends UNION, INTERSECT and IDENTITY  UNION preserves all map features from both the input and overlay map. Logical OR.  INTERSECT preserve only those features that are common to both input and overlay map. Logical AND.

Map Overlay Methods  IDENTITY preserves only map features that fall within the area of the input map. Logical AND/OR. Input map AND overlay or input.

Slivers  Slivers and fuzzy tolerance.  Minimum mapping unit.

Error Propagation in Map Overlay  Positional  Identification  Error quantification

Distance Measurement  Closest  ArcView = Assign Data by Location  ARC/INFO = NEAR and POINTDISTANCE

Map Manipulation  ArcView uses GeoProcessing extension to DISSOLVE, CLIP and MERGE  DISSOLVE is simplification  CLIP is cookie cutter  MERGE combines

Map Manipulation  ARC/INFO uses RESELECT, ELIMINATE, UPDATE, ERASE, and SPLIT  In addition to DISSOLVE, CLIP, MERGE  RESELECT creates new coverage based on logical expression  ELIMINATE creates new coverage by removing features defined by logical expression  UPDATE is cut and paste  ERASE removes features within erase coverage  SPLIT is opposite of merge, breaking into two or more