Rebecca Boger Earth and Environmental Sciences Brooklyn College

 What is GIS? Functions Features Attributes  Data models and databases Vector Raster Geodatabases  How do we know where are we on the Earth’s surface? Datum Projection Coordinates  ArcGIS overview

 Computer system hardware  Geographically referenced digital data  Computer software that carries out various management and analysis tasks  People

1. Much information has a spatial and / or temporal component − Location − Pattern − Trend 2. Quick and easy access to large and varied amounts of data − Search and update data − Model − Analysis 3. Output capabilities – maps, graphs, statistics tailored to desired needs

 Visualization Looking at data on a map to get information see relationships  Geodata management Updating and organizing data to be useful  Analysis Applying tools to answer questions and support decisions

Uses of GIS are almost limitless and apply to most every field Source:

 Location: Where is it?  Condition: What is it?  Trend: What has changed?  Routing: Which is the best way?  Pattern: What is the pattern?  Modeling: What if?

 Analysis : applying tools to geographic data to answer questions  Example: Suppose you own a several coffee shops and want to expand in the same city Question: What are the potential areas for a new shop?

 Shape  Location  Symbol  Attributes

 What is GIS? Functions Features Attributes  Data models and databases Vector Raster Geodatabases  How do we know where are we on the Earth’s surface? Datum Projection Coordinates  ArcGIS overview

 Raster: continuous data, imagine a grid placed over the Earth’s surface  Vector: discrete objects – lines, points and polygons

 Each cell (pixel) has one value distributed over the entire area  Reality – there may be variance within the area E.g., mapping elevation data with a cell size of 30mx30m  Apply a mean, median or modal value, or other type of representation  Can also be coded for categorical data (non numeric), such as land cover type  Can convert between raster and vector

 Spatial data Data with some form of spatial or geographical reference Can be located in 2- or 3-dimensional space  Attribute Data Describes the characteristics of spatial features  Examples: Is it green or blue? How much is it worth? When was it built?  Usually stored in a relational database that is linked to spatial data files

Information stored in tables Each row called a record Each spatial feature is linked to a record Columns or fields recording attributes Source:

Source: ArcGIS desktop help tool

 Geographic data are organized into feature classes  Feature class is a digital dataset with the same shape and attributes  Layer is a visual representation of a feature class in a map  Feature class table as one record and one column for each attribute

 What is GIS? Functions Features Attributes  Data models and databases Vector Raster Geodatabases  How do we know where are we on the Earth’s surface? Datum Projection Coordinates  ArcGIS overview

 How to place a 3D Earth on a flat 2D paper map  Something gives Shape Area Distance Angles  A spherical globe of Earth can preserve all

 Geodesy: science of measuring the shape of the Earth  Create a set of known locations – datum  Map projections transform the datum to a flat surface

 Depiction of spherical Earth on 2D surface  Many different types Designed for different uses Extent of area covered (small or large scale) Where on Earth Shape of area depicted (e.g., long north/south orientation of California versus east/west orientation of Kansas)

 Reference systems: Where are you relative to something else? E.g., city grid and addresses  Latitude and longitude  Universal Transverse Mercator (UTM)

 What is GIS? Functions Features Attributes  Data models and databases Vector Raster Geodatabases  How do we know where are we on the Earth’s surface? Datum Projection Coordinates  ArcGIS overview

 GIS tasks can be categorized into two main functionalities: ArcMap: Mapmaking, editing, and spatial analysis ArcCatalog: database design and data management; search for spatial data, preview it, create and manage metadata  Similar to working with Windows Explorer ArcToolbox: window containing set of tools, merged in ArcMap and ArcCatalog  Overlapping functionalities

 Viewing spatial data by creating and querying a map  Main document has *.mxd extension Map document stores the layers, symbology, and layout, but does NOT store the actual geographic data (can be large files) Directs to where the geographic files are located  Geodatabases help with keeping track of datasets for map project

 Manage your data: find datasets on your hard drive, copy and move datasets around your system, document datasets with metadata  Particularly useful because a single geographic dataset is often composed of multiple files or folders. Copying and deleting sometimes cannot be done with using Microsoft Windows Explorer.

 Geoprocessing Processing geographic information through operations called commands or tools  ArcToolbox important way to conduct geoprocessing Basic analysis tools, conversion tools (import and export), data management tools, geocoding tools, linear referencing tools, and spatial statistic tools  Extensions: provide other tools for geoprocessing

 ESRI data structure  homogeneous collection of features that can have either point, line, or polygon shapes.  “package” of separate files (at least 3) with different extensions.shp: shape file, stores feature geometry.shx: shape index, stores an index to the feature geometry.dbf: dBase file of attribute information can be other files