CFR 250/590 Introduction to GIS, Autumn 1999 Creating Shapefiles & Vector Editing © Phil Hurvitz, 1999-2000create_f_themes.ppt1 Overview Digitizing Creating

© Phil Hurvitz, 1999-2000

CFR 250/590 Introduction to GIS, Autumn 1999

create_f_themes.ppt 1

Creating Shapefiles & Vector Editing

• Overview

• Digitizing• Creating vector data sets• Converting to shapefile• Creating new themes• Snapping• Altering the shape of lines and polygons• Splitting features• Unioning polygons• Combining polygons• Intersecting polygons• Subtracting polygons• Adding attributes• Undoing edits• Saving edits_





• Digitizing

• most common “legacy” method of getting data into a GIS

• tedious & detail-oriented work





• Creating vector data sets

• ArcView supports creation of vector data sets • Point• Line• Polygon

• Complete creation & editing of data sets is supported• Coordinate data• Attribute data





• Converting to shapefile

• Any supported vector data set can be converted to shapefile





• Converting to shapefile

• Selected sets are converted





• Creating new themes

• New themes can be created from scratch





• Snappinggeneral snap tolerance

interactive snap tolerance





• Snapping options

• Snap to an existing vertex

• Snap to an existing line segment or polygon edge

• Snap to an intersection of two or more lines

• Snap to an existing line endpoint





• Altering the shape of lines and polygons





• Splitting features

• Coordinate features (lines & polygons) are split

• Attributes are handled by rules• Blank: values in new records are left blank• Copy: values in new records are copied from the parent record• Proportion: numeric values are proportional to the original area or length• Shape Area: values are the areas of the new polygons• Shape Perimeter: values are the perimeters of the new polygons• Shape Length: values are the lengths of the new lines





• Splitting polygons





• delete erroneouslines

• select erroneouslines

• split the line

• create a line

• Splitting lines





• Unioning polygons

• Multiple features are merged into one • Attributes are handled by rules





• Unioning polygons





• Combining polygons





• Combining polygons





• Intersecting polygons





• Subtracting polygons





• Adding attributes





• Undoing edits

• Edits are undone in reverse order

• Edits can be undone until the last save (or creation)

• Once a theme’s changes are saved, edits cannot be undone





• Saving edits

• Save EARLY and OFTEN

• Edits are saved when:• Theme is closed for editing• Another theme is opened for editing• Project is saved or closed• ArcView is closed

Documents

CFR 250/590 Introduction to GIS, Autumn 1999 Creating Shapefiles & Vector Editing © Phil Hurvitz, 1999-2000create_f_themes.ppt1 Overview Digitizing Creating