Post on 08-Jan-2018
description
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 1
Raster Analysis I
Overview
• Grid themes
• Setting grid theme and analysis properties
• Projections and grid themes
• Grid function types
• Performing grid analysis
• Map Algebra
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 2
Raster Analysis I
Grid themes
• Overview
• Grid theme types
• Grid theme properties
• Adding grid themes to views
• Displaying grid themes
• Examining cell values in grid themes
• Managing grid theme files
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 3
Raster Analysis I
Grid themes: Overview
• Grid themes are ArcView’s implementation of the basic raster data model.
rectangular tessellation of square cells
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 4
Raster Analysis I
Grid themes: Overview
• Grid themes are ArcView’s implementation of the basic raster data model.
•each cell has a numeric value
cell values are
displayed in the
legend
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 5
Raster Analysis I
Grid themes: Overview
• Grid themes are good for representation of phenomena that vary gradually over space
such as elevation, wind speed and direction, or slope
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 6
Raster Analysis I
Grid themes: Grid types
floating-point
integer
only integer grids have theme tables
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 7
Raster Analysis I
Grid themes: The spatial analyst
•All grid theme functionality occurs through the spatial analyst extension.
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 8
Raster Analysis I
Grid themes: Grid theme properties
name disk location
cell size
rows
&
columns
type
status
bounding coordinates
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 9
Raster Analysis I
Grid themes: Adding grid themes to views
updated theme list
new Data Source Type choice
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 10
Raster Analysis I
Grid themes: Displaying grid themes
usually numerically classified
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 11
Raster Analysis I
Grid themes: Examining cell values in grid themes
histogram shades match theme legends
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 12
Raster Analysis I
Grid themes: Examining cell values in grid themes
histograms can be createdfor polygonal zones
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 13
Raster Analysis I
Grid themes: Examining cell values in grid themes
integer grid
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 14
Raster Analysis I
Grid themes: Examining cell values in grid themes
integer
grid
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 15
Raster Analysis I
Grid themes: Managing grid theme data files (and shapefiles)
new menu choice
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 16
Raster Analysis I
Grid themes: Managing grid theme data files (and shapefiles)
delete
rename
copy
sourcetype
datasourcename
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 17
Raster Analysis I
Setting grid theme and analysis properties
• Spatial extent
• Cell size
• Masking
Analysis properties determine grid theme properties for all output grid themes
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 18
Raster Analysis I
Setting grid theme and analysis properties: Spatial extent
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 19
Raster Analysis I
Setting grid theme and analysis properties: Cell size
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 20
Raster Analysis I
Setting grid theme and analysis properties: Masking
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 21
Raster Analysis I
Setting grid theme and analysis properties: Masking
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 22
Raster Analysis I
Projections and grid themes
ArcView cannot project grid themes on the fly as it projects feature themes.
• Do not view unprojected grid themes with projected vector themes.
• View projected grid themes with unprojected vector themes by setting view projection properties.
• If you need to project a grid theme to match projected vector themes, use ARC/INFO.
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 23
Raster Analysis I
Grid function types
• Global functions
• Zonal functions
• Focal functions
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 24
Raster Analysis I
Grid function types: Global functions
Global functions apply one calculation to all input grid cells.
global sine
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 25
Raster Analysis I
Grid function types: Zonal functions
Zonal functions apply one calculation to all input grid cells within each zone.
zonal sum
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 26
Raster Analysis I
Grid function types: Focal functions
Focal functions apply one calculation to all input grid cells within a “focus.”
focal mean
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 27
Raster Analysis I
Performing grid analysis: Map algebra (or “How it works”)
• multiple grid themes share the same X, Y coordinate space
• cell values are calculated across multiple grid themes
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 28
Raster Analysis I
Performing grid analysis: Map algebra
map algebra calculations are performed with GUI tools
grid themes(layers)
operators
expression box
operator classes
© Phil Hurvitz, 1999-2000
CFR 250/590 Introduction to GIS, Autumn 1999
raster1.ppt 29
Raster Analysis I
Performing grid analysis: Map algebra (or “How it works”)
grid themes may be used in algebraic functions
output_data_set = function (input_data_set(s) {,arguments})slp_grid = slope (dem, percentrise)
grid themes may be used in algebraic expressions
output_data_set = input_grid1 operator input_grid2 . . .
slp_dem = slp_grid * dem