Major parts of ArcGIS•ArcView -Basic mapping, editing and Analysis tools•ArcEditor -all of ArcView plus Adds ability to deal with topological and network editing-additional stuff in Arctoolbox•ArcInfo- fully functional everything

Definitions• Features

– points, lines, or polygons with x,y coordinates marking the location of points, nodes or vertices• Node- the end points of a line• Vertices - the corners of a polygon

• Feature Classes– Contains a number of different

features that are all the same type of geometry• e.g., they can multiple feature files that

are all point features, but not some combo of points, lines and polygons

Data Types• Raster vs Vector• Raster is turning pixels on and off and

giving them values – Advantages- looks like a photograph– Disadvantages- at high magnification things

can look jagged as pixels are square

• Vector- uses x,y coordinates to create points, lines and shapes– Advantage is things are smooth at high

magnification– Disadvantage is that it looks like a line

drawing

Data files in ArcGIS• Shapefiles

– Vector data files– Can be points, lines or polygons– Cannot store topological data– Files have the suffixes .shp, .dbf

or .shx– Icons are green with different symbols

for points lines and polygons

Icons for the three types of vector features

Data files in ArcGIS

• Coverages- topological data sets that contain multiple features classes

• Files are commonly spread among multiple folders

• Coverages have a folder with files that have the suffix .adf and a file called info that must be in the same location as the .adf file

• Geodatabases- one of the newer types of files

• Contains multiple types of of features classes

• Can also contain tabular files that are not linked to spatial locations

• They can store topological relationships between different data sets

Data files in ArcGIS

• Layer files-A layer file contains references to spatial data and how it should be displayed and what basic properties it has– Example, a layer file with basic map

symbols can be placed into any work so that there is consistency between jobs (maps) of various types

Data files in ArcGIS

• RASTERS- rasters are arrays of numbers stored in binary format. RASTER files have the data itself, plus some critical information about how the array is set up and how it is georeferenced

• These can be displayed in a variety of ways, but can only be analyzed when they are converted to grid files

Data files in ArcGIS

• Tables- these can exist as separate files or associated with other files.

• They can have the suffix .dbf (database file) or as comma delimited text files

• INFO files are commonly stored as standalone tables with a yellow stripe at the top of the table

Data files in ArcGIS

• Grids - a specialized data file developed by the software manufacturer to allow for rapid manipulation or analysis of RASTER data

Data files in ArcGIS

• TINs- Triangulated Irregular Networks store surface information such as elevation

• Uses nodes (points) to define triangular shaped planar surfaces.

• Tins are used to create contour maps and analyze 3D surface information

Data files in ArcGIS

Metadata

• Data about the data– Includes

• who created the file• What coordinate system it uses• What the fields in the attribute tables mean

– What are the abbreviations• Plus other information

– It is time consuming to create, but ArcGIS will assist in the adding information to the file and in making sure that the metadata stays with the appropriate files

ArcCatalog

• Like having windows explorer operating within the GIS software– It knows how to organize and

manipulate and store information within itself

Topological models

• How features (polygons, points, lines) relate to each other– Adjacency- sharing of a boundary

• State lines, county lines

– Connectivity- how things connect• if one stream flows into another stream

– Overlap- if data relates to same are more than once

• Spraying of pesticides over the same area

– Intersection- types of interactions• Highway goes over or has onramps to a crossing

road

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Precision

vs

Accuracy

Accuracy

• Geometric Accuracy– How closely do the x,y coordinates of

features or raster data reflect their position on the earth?

• Thematic Accuracy– Refers to the accuracy of attributes

• Is the population of the city really 734, or is it 7340?

Image service vs Feature service data servers

• Image services– Can view and print out images, but

cannot download or manipulate the files

• Feature services– Can download, view, and printout

data

• http://www.geographynetwork.com

Try to find one of each on this site.