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Overview

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

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Overview

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  1. 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

  2. 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

  3. 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

  4. USGS source Importing data from generic raster files • USGS DEMs are available online (free)

  5. 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

  6. 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

  7. Continuous surface discrete sample points Creating surfaces from point samples • Points are interpolated to a surface

  8. spline (minimized curvature) • inverse distance weighting (local influence is strong) Creating surfaces from point samples • Two basic methods (spline and IDW)

  9. 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_

  10. 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

  11. new layer Mapping contours • Group of contours created as shapefile

  12. 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

  13. Summarizing zones • 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

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

  15. Summarizing zones • Table and chart are created statistics from input grid based on polygonal zones

  16. 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

  17. 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

  18. area measurementsin map units Cross tabulating areas column layer (stands) • Output table row layer (soils)

  19. 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

  20. "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

  21. 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

  22. 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

  23. Calculating neighborhood statistics locations of greatest variationin elevation • Focal Standard Deviation

  24. Calculating neighborhood statistics: high pass filter • High-pass filter (focal process)

  25. Calculating neighborhood statistics: high pass filter edges are higher or in absolute value • High-pass filter finds edges

  26. 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

  27. 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

  28. continuous distance value surface Calculating distance surfaces and buffers • Distance from vector features

  29. 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

  30. Assigning proximity • “what territories are closest to a set of features?” • output cells have the value of the closest input feature “Thiessen,” “Voronoi”

  31. 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

  32. 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)

  33. polygon shapefile Converting raster and vector data sources: grid to polygon • Convert grid zones to polygon shapefile

  34. GRIDCODEfield Converting raster and vector data sources: grid to polygon • Convert grid zones to polygon shapefile

  35. Value field Converting raster and vector data sources: grid to polygon • Convert vector lines to grid zones

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