GIS_4

What are the 3 required files?

.shp, .shx, .dbf.

Data Table Joins: Problems with Table Joins?

1) Field for key attribute must have same type (ex. one is numberic and other one is text). However, Field names can be different. 2) Data formats varies.

Tables: Each attribute table has a Primary Key Attribute with 2 properties:

1. Each value is unique. 2. There are no null values.

Define GeoCoding?

A GIS operation for converting street addresses into spatial data that can be displayed as features on a map, usually by referencing address information from a street segment data layer.

Define Coverage?

A data model for storing geographic features. A coverage stores a set of thematically associated data considered to be a unit. It usually represents a single layer, such as soils, streams, roads, or land use. In a coverage, features are stored as both primary features (points, arcs, polygons) and secondary features (tics, links, annotation). Feature attributes are described and stored independently in feature attribute tables. coverage cannot be edited in ArcGIS 8.3 and subsequent versions.

Define Attribute Table?

A database or tabular file containing information about a set of geographic features, usually arranged so that each row represents a feature and each column represents one feature attribute. In raster datasets, each row of an attribute table corresponds to a certain zone of cells having the same value. In a GIS, attribute tables are often joined or related to spatial data layers, and the attribute values they contain can be used to fine, query, and symbolize features or raster cells.

Spatial Data Formats: ESRI format: Coverage?

A folder with multiple files. Can include points, lines, and/or polygons. Have a topology (that is a set of rules between points, lines and polygons to eliminate overlapping and gaps.

GeoDataBase?

A geodatabase is a container used to hold a collection of datasets (GIS features, tables, raster images, and other objects).

Tables: External table file formats for IMPORT into ArcGIS: (.csv)?

A plain ASCII text with Comma Separated Values (.csv). Very compatible. Each table's record is a row terminated with a line-break character (invisible, nonprinting value). Values are delimited (usually comma or whitespace). For data values that contain a delimiter, enclose the value in double quotes. Sometimes columns get wrong data type on import (ex. use double quotes to force text data type for digits.)

Define Attribute Query?

A request for records of features in a table based on their attribute values.

Spatial Data Formats: ESRI format: Shapefile?

A shapefile consists of multiple files, all with the same prefix name but different file extensions. It is more commonly used and has a simpler structure THAN coverage.

Define Location Query?

A statement or logical expression that selects geographic features based on location or spatial relationship. Ex. a spatial query might find which points are contained within a polygon or set of polygons, find features within a specified distance of a feature, or find features that are adjacent to each other.

Define Spatial Join?

A type of table join operation in which fields from one layer's attribute table are appended to another layer's attribute table based on the relative locations of the features in the two layers.

Define Shapefile?

A vector data storage format for storing the location, shape, and attributes of geographic features. A shapefile is stored in a set of related files and contains one feature class.

Define ANSI?

Acronym for American National Standards Institute. The private, nonprofit organization that develops US industry standards through consensus and public review.

Define ASCII?

Acronym for American Standard Code for Information Interchange. The de facto standard for the format of text files in computers and on the Internet that assigns a 7-bit binary number to each alphanumeric or special character. ASCII defines 128 possible characters.

Define FIPS Codes?

Acronym for Federal Information Processing Standards (FIPS) codes. It represent an official coding system developed by the National Institute of Standards and Technology (NIST) [known between 1901 and 1988 as the National Bureau of Standards (NBS)], an agency of the US Department of Commerce. FIPS codes are assigned for a variety of geographic entities including American Indian and Alaska Native Area, Hawaiian home lands, congressional districts, counties, county subdivisions, metropolitan areas, places and states. In the US, a 5-digit FIPS code is assigned to each county. each state has its own 2-digit number, and each county within the state has its own 3-digit number, which are combined to uniquely identify every US county. Ex. a FIPS code of 06071 represent California (06) and San Bernardino County (071).

Calculate x, y fields?

Add new X and Y fields in the attribute table.

GEOCODES: With the geocoding capability of ArcGIS, an ??? (that is nonspatial data) can be converted into a point (spatial data) that corresponds to that address by using an ???, either for mapping or for combining with other data.

Address. Address Locator.

File GeoDataBase?

An ESRI replacement for Shapefiles. Stores vector and raster map layers. Stores other objects (ex. tables). Stores 1 or more datasets in a folder of files with. gdb extension. Can be up to 1 TB in size. Can be used across platforms. Can be compressed and encrypted for read-only, secure use.

Define Relate?

An operation that establishes a temporary connection between records in two tables using a key common to both.

Define Attribute Join?

Appending the fields of one table to those of another table through an attribute common to both tables (called a key attribute)

Define Joining?

Appending the filed of one table to those of another through an attribute or field common to both tables. A join is usually used to attach more attributes to the attribute table of a geographic layer.

??? can show the user which folders contain spatial data and what kinds of spatial data are contained in those folders.

ArcCatalog.

Each Spatial Data Format is identified by its own icon in ???. The icon for a geodatabase is a ???

ArcCatalog. Cylinder.

??? provides user more information about ??? data than user can get from Windows Explorer or other file browsers.

ArcCatalog. Spatial.

What are other geometry calculations?

Area, Perimeter, and Lenth. Both Area and Perimeter are Polygon Features, while Length is Line Feature.

Tables: First row of attribute table includes ???.

Attribute (that is variable) names.

Tables: Spatial Table?

Attribute Table associated with a geometry (that is point, line, polygons) on a map layer. Attribute data stored in a table is part of map layers.

Categorical Attributes? aka. Qualitative or Descriptive Attributes

Attributes that are either Names or Descriptions are called Categorical Attributes. They are usually text (that is characters), but they could be numbers if the numbers are CODES standing for descriptions or if they are ranges of numbers that compose category (ex. population ranges, rather than a specific population count).

Quantitative Attributes?

Attributes that are either measurements or counts of features.

Viewing Geodatabase?

Cannot identify file names in Windows Explorer. Must use ArcCatalog.

2 kinds of Attributes?

Categorical vs Quantitative Attributes

Tables: Rectangular table with one value per cell: ??? are variables (aka. fields or attributes).

Columns.

GEOCODES: Example of FIPS codes:

Country: US State: 42 (Pennsylvania) County: 003 (Allegheny) Minor civil division: 42 003 61000 (Pittsburgh)

Spatial Data Formats: ESRI format: Coverage: In ArcCatalog?

Coverage contains Coverage Feature Classes.

Data Table Joins: Solutions with Table Joins when field for key attribute are not the same? One is text, and other one is numberic.

Create a NEW field of same type and use Field Calculator.

Tables: Nonspatial Table?

Data table with geocodes that does not have a geometry associated with. Can add as a table to ArcMap. Can join to a map layer to add more attributes to that map layer.

Data Table Joins: Solutions with Table Joins when Data formats are different?

Example. Table A has 48-S-91, but Table B has 48S91. We must remove these dashes in these attribute values before table join.

Tables: External table file formats for IMPORT into ArcGIS: Excel (.xls, .xlsx)?

Excel 2003, up to 65,000 rows and 256 columns. Excel 2007, up to 1,048,576 rows and 16,384 columns.

Geocodes: Hierarchical?

FIPS codes (political boundaries) > Census codes (statistical boundaries) > Local government cadastral data (legal boundaries)

A ??? can be exported into a shapefile.

Feature class.

GEOCODES: ??? (FIPS) develop by the National Institute of Standards and Technology (NIST) [Formerly National Bureau of Standards (NBS)]. And codes for place-names throughout the world, include countries, states/provinces, counties, metropolitan statistical areas (MSA's), cities, and places.

Federal Information Processing Standards (FIPS). Geocodes (2000).

A Shapefile can be imported into a ??? as a feature class.

File GeoDataBase.

.gdb?

File geodatabase.

A ??? is created by ArcMap and ArcCatalog desktop software, but not by an external software.

File geodatabase.

The Shapefile format defines the ??? and ??? of geographically referenced features in 3 or more files with specific file extensions that should be stored in the same project workspace.

Geometry and Attribute.

Define Event Layer?

In ArcGIS, a layer created from an event table.

Define Definition Query?

In ArcMap, a request that examines feature or tabular attributes based on user-selected criteria, which displays only those features or records that satisfy the criteria.

Define Topology?

In geodatabases, the arrangement that constrains how point, line, and polygon features share geometry. Ex. street centerlines and census blocks share geometry, and adjacent soil polygons share geometry. Topology defines and enforces data integrity rules (ex. there should be no gaps between polygons). It supports topological relationship queries and navigation (ex. navigating feature adjacency or connectivity), supports sophisticated editing tools, and allows feature construction from unstructured geometry (ex. constructing polygons from lines).

Define Spatial Data?

Information about the locations and shapes of geographic features and the relationships between them, usually stored as coordinates and topology.

Data Table Joins: Matching Variables? Which Variables are good candidates for matching between Spatial and Nonspatial tables?

It is poor practice to choose Location Names as Matching Variables as spellings may vary (ex. St. vs Saint Martinville, and misspeeling). A new variable must be created for the Nonspatial dataset. If the matching variables in spatial dataset is in text, then the new variable must be in text format as well. Again, Matching Variables do NOT NEED have same name.

Data Table Joins: Example of Many-to-One (M:1) Join?

Join a code table to a feature attribute table to add code description.

Data Table Joins: Example of One-to-One (1:1) Join?

Join a state nonspatial table to a state shapefile attribute table by StateName.

Spatial Joins?

Joins DIFFERENT layers using physical spatial relationships (not attribute field). Enables data aggregation (ex. counting points by polygon). Most appropriate when a matching variable is Unavailable (that is an attribute join CANNOT be performed).

Tables: First character of Attribute Name must be a ???

Letter. Remaining characters can be any letter, digit, or the underscore character, but no blanks, or special symbols). Maximum length a field can hold is 256 characters.

Define Attribute?

Nonspatial information about a geographic feature in a GIS, is usually stored in a table and is linked to the feature by a unique identifier. Example: attributes of a river might include its name, length, and sediment load at a gauging station. In raster datasets, information associated with each unique value of a raster cell.

GEOCODES: Example of Local Government Cadastral Data:

Parcel Block & Lot Number: 0096-P-0021000000 (1690 Seaton St., Pittsburgh, PA 15226)

Spatial Joins: What are 3 common Spatial Joins?

Points to Polygons (counts) Polygons to Points (add polygon info to points) &, Points to Points (compute distances)

Table Joins?

Put 2 tables together, on the fly, to make 1 table. Each table in a table join must have a key attribute (that is a common field) for matching. Must have same values and data types for key attribute in both tables.

Spatial Joins: Example of Points to Points?

Q: How close is the nearest bus stop (that is point) to a business (that is point)? Start with business point, bus stop point > Right-click business points > Joins and Relates > Join. In addition, select the Distance Field that is "Each point will be given all the attributes of the point in the layer being joined that is closest to it, and a Distance Field showing how close that point is in the units of the target layer. Distance Field added to a new layer of businesses and bus stops joined.

Spatial Joins: Example of Points to Polygons?

Q: How many businesses (that is points) are in each neighborhood (that is polygon)? Start with Business points, neighborhood polygons > Right-click Neighborhoods > Joins and Relates > Join. A new polygon layer with count of points. Shown as a choropleth map with labels, or table.

Spatial Joins: Example of Polygons to Points?

Q: What neighborhood (that is polygon) is a business (that is point) located in? Start with Neighborhood polygons, business points > Right-click business points > Joins and Relates > Join. A point shapefile with neighborhood data on each business.

Data Table Joins: How to access Attribute Joins?

Right Click the Layer of your choice.

Tables: Rectangular table with one value per cell: ??? are observations (that is records).

Rows.

A ??? is a simple, nontopological format for storing the geometric location and attribute information of geographic features. A ??? (same) is one of the spatial data formats that we can work with and edit in ArcGIS.

Shapefile.

??? comes in many different formats, including geodatabases, coverages, shapefiles, CAD (computer-aided design) files, rasters, and TINs (triangulated irregular networks).

Spatial Data Format.

2 kinds of Tables in ArcGIS?

Spatial vs Nonspatial Table

GeoCodes (2010) ANSI Codes?

Standards for: American National Standards Institute (ANSI) Codes. Expands the FIPS. Entities covered include: states and statistically equivalent entities, counties and statistically equivalent entities, named populated and related location entities (such as places and county subdivisions), and American Indian and Alaska Native areas.

Personal Geodatabase?

Stores datasets in a Microsoft Access .mdb file (intrinsically a different kind from a .gdb file). Limited to 2 GB. Much overhead in space and extra structure. Tempting to apply one's own Access skills, but needs ArcGIS Catalog utility for manipulation. A personal geodatabase (that is .mdb) can also be created by ArcMap and ArcCatalog desktop software.

GeoCode?

Takes a table of addresses and converts them to actual locations with latitude and longitude. Convert street address to point on ArcMap.

Data Table Joins: Text values are ??? align while Numberic values are ??? align.

Text = Left Numberic = Right

.dbf?

The dBASE table that stores the attribute information of features; required.

Calculating Centroids: Point Centroids?

The geographic centers of polygons. Play a key role in spatial analysis.

Define Centroid?

The geometric center of a feature.

.shx?

The index file that stores the index of the feature geometry; required.

.shp?

The main file that stores the feature geometry.

Define Spatial Analysis?

The process of examining the locations, attributes, and relationships of features in spatial data through overlay and other analytical techniques in order to address a question or gain useful knowledge. Spatial analysis extracts or creates new information from spatial data.

Define Join Table?

The table in a join operation, often a nonspatial table, that is appended to the target layer's attribute table.

Define Target Table?

The table in which new attributes are appended. Records in a target table are often referred to as target features.

Define GeoCode?

To assign a street address to a location. When used as a noun, refers to a code representing the location of an object, ex. an address, a census tract, a postal code, or x-/y-coordinates.

GEOCODES: Example of Census codes:

Tract: 1917 Block Group: 003 Block: 005 (US 42 003 1917 003 005)

Tables: External table file formats for IMPORT into ArcGIS: Microsoft Access Database (.mdb)?

Up to 2GB file size.

A Shapefile is only for ??? data, and not for ??? data.

Vector. Raster.

Export features?

X and Y events should be exported as a permanent shapefile.

Tables: External table file formats for IMPORT into ArcGIS: dBase database table (.dbf)?

dBase IV has a maximum of 255 fields per record. Can open dBase file in Excel but cannot save dBase from Excel.