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Overview• Importing data from generic raster files• Creating surfaces from point samples• Mapping contours• Calculating summary attributes for polygon

features using a grid layer (“Zonal Statistics”)• Cross tabulating areas• "Querying" across multiple grid layers• Calculating neighborhood statistics• Calculating distance surfaces and buffers• Determining proximity• Converting raster and vector data sources

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Overview• Importing data from generic raster files• Creating surfaces from point samples• Mapping contours• Calculating summary attributes for polygon

features using a grid layer (“Zonal statistics”)• Cross tabulating areas• "Querying" across multiple grid layers• Calculating neighborhood statistics• Calculating distance surfaces and buffers• Determining proximity• Converting raster and vector data sources

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Importing data from generic raster files

• ArcGIS can import grids from 4 different generic raster data formats– ASCII raster file format– binary raster file format– USGS Digital Elevation Model (DEM) raster

file format*– US DMA (Defense Mapping Agency) DTED

(Digital Terrain Elevation Data) raster file format

* common format; free for download from USGS

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Importing data from generic raster files

• USGS DEMs are available online (free)

USGS source

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Overview• Importing data from generic raster files• Creating surfaces from point samples• Mapping contours• Calculating summary attributes for polygon

features using a grid layer (“Zonal statistics”)• Cross tabulating areas• "Querying" across multiple grid layers• Calculating neighborhood statistics• Calculating distance surfaces and buffers• Determining proximity• Converting raster and vector data sources

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Creating surfaces from point samples

• Generation of a complete surface from incomplete point samples

• Interpolation between and beyond individual sample points

• Better estimation of surface value in locations near sample points

• Several different interpolation methods available• Assumption of gradual change of value across

landscape

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Creating surfaces from point samples• Points are interpolated to a surface Contin

uous surface

discrete sample points

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Creating surfaces from point samples

• Two basic methods (spline and IDW)

• spline (minimized curvature)

• inverse distance weighting (local influence is strong)

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Overview• Importing data from generic raster files• Creating surfaces from point samples• Mapping contours• Calculating summary attributes for polygon

features using a grid layer (“Zonal statistics”)• Cross tabulating areas• "Querying" across multiple grid layers• Calculating neighborhood statistics• Calculating distance surfaces and buffers• Determining proximity• Converting raster and vector data sources_

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Mapping contours

• Finds adjacent cells of the same value

• Converts linear arrangement of raster cells to vector lines

• User control of base contour and contour interval

• Few digitized contour line data sets exist for remote areas

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Mapping contours

• Group of contours created as shapefilenew layer

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Overview• Importing data from generic raster files• Creating surfaces from point samples• Mapping contours• Calculating summary attributes for polygon

features using a grid layer (“Zonal statistics”)• Cross tabulating areas• "Querying" across multiple grid layers• Calculating neighborhood statistics• Calculating distance surfaces and buffers• Determining proximity• Converting raster and vector data sources

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• Defines a zone of cells based on a group of integer cells or polygons with same value

• Creates statistical summary of zone

• Summary table is created

• Summary chart

Summarizing zones

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• “Zone” is a group of cells (or polygons) that have the same attribute value

Summarizing zones

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• Table and chart are created

statistics from input grid based on polygonal zones

Summarizing zones

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Overview• Importing data from generic raster files• Creating surfaces from point samples• Mapping contours• Calculating summary attributes for polygon

features using a grid layer (“Zonal statistics”)• Cross tabulating areas• "Querying" across multiple grid layers• Calculating neighborhood statistics• Calculating distance surfaces and buffers• Determining proximity• Converting raster and vector data sources

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Cross tabulating areas• Creates a “zonal intersection” of integer grid

layers (similar to vector intersection)

• Output is a table

• 1st input layer creates records (1 record for each unique value)

• 2nd input layer creates fields (1 field for each unique value)

• Table values are map unit area measurements of combinations of zones

• Valuable technique for change detection

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Cross tabulating areas• Output table

row

laye

r (s

oils

)

column layer (stands)

area measurementsin map units

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Overview• Importing data from generic raster files• Creating surfaces from point samples• Mapping contours• Calculating summary attributes for polygon

features using a grid layer (“Zonal statistics”)• Cross tabulating areas• "Querying" across multiple grid layers• Calculating neighborhood statistics• Calculating distance surfaces and buffers• Determining proximity• Converting raster and vector data sources

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"Querying" across multiple grid layers (“Map Query”)

• Raster Calculator is easy to use and gives rapid results

• Results may be as good as vector overlay depending on cell size & relative precision

• Multiple grids can be simultaneously queried(whereas only 2 vector layers can be compared in vector overlay)

• Output represents cells that meet and do not meet query criteria

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Overview• Importing data from generic raster files• Creating surfaces from point samples• Mapping contours• Calculating summary attributes for polygon

features using a grid layer (“Zonal statistics”)• Cross tabulating areas• "Querying" across multiple grid layers• Calculating neighborhood statistics• Calculating distance surfaces and buffers• Determining proximity• Converting raster and vector data sources

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Calculating neighborhood statistics

• “Focal” statistical functions

• Moving focus window calculates statistics for all cells within focus

• Output value is written to central cell in output grid

• Statistical functions:• Minimum• Maximum• Mean• Median• Sum

• Range• Standard Deviation• Majority• Minority• Variety

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Calculating neighborhood statistics

• Focal Standard Deviationlocations of greatest variationin elevation

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Calculating neighborhood statistics: high pass filter

• High-pass filter (focal process)

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Calculating neighborhood statistics: high pass filter

• High-pass filter finds edges edges are higher or in absolute value

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Overview• Importing data from generic raster files• Creating surfaces from point samples• Mapping contours• Calculating summary attributes for polygon

features using a grid layer (“Zonal statistics”)• Cross tabulating areas• "Querying" across multiple grid layers• Calculating neighborhood statistics• Calculating distance surfaces and buffers• Determining proximity• Converting raster and vector data sources

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Calculating distance surfaces and buffers

• Similar to buffering with vector data

• Creates a continuous distance surfacerather than a discrete bounded polygonal area

• Distance measured from input layer featuresor grid cells

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Calculating distance surfaces and buffers

• Distance from vector features

continuous distance value surface

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Overview• Importing data from generic raster files• Creating surfaces from point samples• Mapping contours• Calculating summary attributes for polygon

features using a grid layer (“Zonal statistics”)• Cross tabulating areas• "Querying" across multiple grid layers• Calculating neighborhood statistics• Calculating distance surfaces and buffers• Determining proximity• Converting raster and vector data sources

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Assigning proximity• “what territories are closest to a set of

features?” • output cells have the value of the closest input feature

“Thiessen,” “Voronoi”

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Overview• Importing data from generic raster files• Creating surfaces from point samples• Mapping contours• Calculating summary attributes for polygon

features using a grid layer (“Zonal statistics”)• Cross tabulating areas• "Querying" across multiple grid layers• Calculating neighborhood statistics• Calculating distance surfaces and buffers• Determining proximity• Converting raster and vector data sources

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Converting raster and vector data sources

• Raster vector conversions are possible

• Always a loss or generalization of shape

• Support for point, line, polygon grid in ArcGIS

• Avoid converting grids that do not have large contiguous zones (e.g., DEMs)

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Converting raster and vector data sources: grid to polygon

• Convert grid zones to polygon shapefilepolygon shapefile

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Converting raster and vector data sources: grid to polygon

• Convert grid zones to polygon shapefileGRIDCODEfield

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Converting raster and vector data sources: grid to polygon

• Convert vector lines to grid zones

Value field