CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 1  Overview Grid themes Setting grid theme and analysis properties Projections and grid themes Grid function types Performing grid analysis Map Algebra

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 2  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

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 3  Grid themes: Overview Grid themes are ArcView’s implementation of the basic raster data model. rectangular tessellation ofsquare cells

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 4  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

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 5  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

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 6  Grid themes: Grid types floating-pointinteger only integer grids have theme tables

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 7  Grid themes: The spatial analyst All grid theme functionality occurs through the spatial analyst extension.

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 8  Grid themes: Grid theme properties name disk location cell size rows & columns type status bounding coordinates

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 9  Grid themes: Adding grid themes to views updated theme list new Data Source Type choice

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 10  Grid themes: Displaying grid themes usually numerically classified

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 11  Grid themes: Examining cell values in grid themes histogram shades match theme legends

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 12  Grid themes: Examining cell values in grid themes histograms can be created for polygonal zones

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 13  Grid themes: Examining cell values in grid themes integer grid

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 14  Grid themes: Examining cell values in grid themes integer grid

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 15  Grid themes: Managing grid theme data files (and shapefiles) new menu choice

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 16  Grid themes: Managing grid theme data files (and shapefiles) delete rename copy source type data source name

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 17  Setting grid theme and analysis properties Spatial extent Cell size Masking Analysis properties determine grid theme properties for all output grid themes

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 18  Setting grid theme and analysis properties: Spatial extent

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 19  Setting grid theme and analysis properties: Cell size

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 20  Setting grid theme and analysis properties: Masking

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 21  Setting grid theme and analysis properties: Masking

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 22  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.

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 23  Grid function types Global functions Zonal functions Focal functions

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 24  Grid function types: Global functions Global functions apply one calculation to all input grid cells. global sine

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 25  Grid function types: Zonal functions Zonal functions apply one calculation to all input grid cells within each zone. zonal sum

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 26  Grid function types: Focal functions Focal functions apply one calculation to all input grid cells within a “focus.” focal mean

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 27  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

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 28  Performing grid analysis: Map algebra map algebra calculations are performed with GUI tools grid themes (layers) operators expression box operator classes

CFR 250/590 Introduction to GIS, Autumn 1999 Raster Analysis I © Phil Hurvitz, raster1.ppt 29  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