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© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 1
Vector Analysis I
Where have we come so far?
• What GIS is.
• How GIS works.
• Some of what GIS can do.
• GIS data formats.
• Spatial data.
• Tabular data.
• Modifying views of data.
By now, you should be familiar with:
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 2
Vector Analysis I
What comes next?
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 3
Vector Analysis I
Basic vector analysis
• Which forest stands lie within 100 m of a road?
• Which inventory plots have been affected by a recent slope failure?
• Does any stream pass through the oldest stands in a forested area?
• What is the age-class distribution of stands adjacent to stands younger than 10 years?
• What is the mean slope of the group of stands within 50 m of a stream?
Examples
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 4
Vector Analysis I
Overview of basic vector analysis
• Analyzing spatial relationships
• Theme-on-theme selection
• Selecting points near a line
• Selecting adjacent features
• Line-on-polygon selection
• Polygon-on-line selection
• Point-in-polygon selection
• Polygon-on-point selection
• Polygon-on-polygon selection
• Spatial join
• Spatial join: containment
• Spatial join: proximity
• Spatial merge
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 5
Vector Analysis I
Analyzing spatial relationships
• Proximity
• Containment
• Overlap
Relationships between features
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 6
Vector Analysis I
Theme-on-theme selection
• Definitions
• Target theme: the theme we want to know something about
• Selector theme: the theme we are spatially referencing to
• For a series of streams, find the distance to the nearest forest stand
target theme selector theme
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 7
Vector Analysis I
Theme-on-theme selection: feature type relationships
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 8
Vector Analysis I
gates near streams
Selecting points near a line (proximity)
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 9
Vector Analysis I
Selecting adjacent features (proximity of 0)
stands adjacent to other stands
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 10
Vector Analysis I
Line-on-polygon selection (intersection, proximity of 0, overlap)
roads and streams within stands
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 11
Vector Analysis I
Polygon-on-line selection (intersection, proximity of 0, overlap)
stands traversed by streams
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 12
Vector Analysis I
CFI plots within 30-40 y old stands
Point-in-polygon selection (containment)
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 13
Vector Analysis I
conifer basal area statistics
Point-in-polygon selection
30-40 year old stands are underrepresented in inventory
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 14
Vector Analysis I
Polygon-on-point selection
stands containing non-forestedor unsampled plots
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 15
Vector Analysis I
Polygon-on-polygon selection (containment, overlap)
stands overlapping with unstable soils
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 16
Vector Analysis I
Spatial join
• theme attribute tables are joined on the shape field
• features are related and compared for distance and containment
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 17
Vector Analysis I
Spatial join: containment
polygon attributes are attached to points
related fields can be used for display
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 18
Vector Analysis I
Spatial join: proximity
distance from plot centers to roads
distance used as a display field
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 19
Vector Analysis I
Spatial merge
• features with identical attribute values are merged together
• table records are joined
• a new theme is created
• a special case of the tabular summary
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
vector_analysis_1.ppt 20
Vector Analysis I
Spatial merge
summarize the Age_Class_1999field
creates a new theme