How to Pick a GIS Getting Started With GIS Chapter 8

8 How to Pick a GIS 8.1 The Evolution of GIS Software 8.2 GIS and Operating Systems 8.3 GIS Software Capabilities 8.4 GIS Software and Data Structures 8.5 Choosing the Best GIS

Choosing the GIS n GIS users need to be aware of different GIS software products during system selection and beyond n OpenGIS (OGC) standards have led to a new generation of choices for software n Informed choice is the best way to select the best GIS

Functionality n What functions must GIS perform? n What functions can it perform? n What software has what functions? n First management step is often to make a requirements matrix: needs vs. capabilities

A functional definition of GIS n A GIS is often defined not for what it is but for what it can do. n If the GIS does not match the requirements for a problem, no GIS solution will be forthcoming. n A GIS may have overcapacity.

GIS as a toolbox… n How did functions develop over time? n What are the differences among software packages? n What are any given packages strengths and weaknesses? n What other factors come into play, cost, training, maintenance, robustness, etc.

GIS software in 1979 n A historical GIS “snapshot” was the IGC survey conducted in 1979 n In the 1979 survey, most GISs were sets of loosely linked FORTRAN programs performing spatial operations n Computer mapping programs had evolved GIS functionality

GIS in the 1980s n spreadsheet was ported to the microcomputer, allowing “active” data n relational DBMS evolved as the leading means for database management n single integrated user interface n degree of device independence n led to the first true GIS software

GIS in the 90s n used graphical user interfaces and the desktop/WIMP model n Unix workstations integrated GIS with the X-windows GUI n GISs began to use the OS GUI instead of their own n PCs integrated GIS with the variants of Windows and other OSs

X windows and the GUI

GIS in the 2000s n Mobile systems n Web-based extensions n Distributed systems and data n Most software now object-oriented n New competition: OpenSource n Web services n Location-based services

Trends still under way n Open Source development tools now ubiquitous, e.g. geotools libraries n GoogleEarth, Virtual Earth, etc. n Mash-up solutions

The “critical six” functional capabilities n data capture n storage n management n retrieval n analysis n display

Data capture functions n digitizing n scanning n mosaicing n editing n generalization n topological cleaning

Steps in mosaicing

Rubber sheeting

Line generalization

Storage functions n compression n metadata handling n control via macros or languages n format support

Compression n By data structure u quad trees u run length encoding n By data format u compressed TIF u jpeg n By physical compression u digit handling

Data management functions n physical model support n DBMS n address matching n masking n cookie cutting

Cookie cutting

Data retrieval functions n locating n selecting by attributes n buffering n map overlay n map algebra

Map algebra

Data analysis functions n interpolation n optimal path selection n geometric tests n slope calculation

Interpolation ?

Data display functions n desktop mapping n interactive modification of cartographic elements n graphic file export

Functional capabilities are by- products of data structure n Raster systems work best in forestry, photogrammetry, remote sensing, terrain analysis, and hydrology. n Vector systems work best for land parcels, census data, precise positional data, and networks.

Vector n Precision intact n Used when individual coordinates are important n More concise spatial description n Assumes feature model of landscape n Easy to transform data e.g. map projections

Raster n Better for field data n Used by most imaging systems n Can be compressed n Easy to display and analyze n Many common formats n However, most systems now use both n Raster layer often backdrop-onscreen editing

The Big Eight n Form the bulk of operational GIS in professional and educational environments n There are some significant differences between these “big eight” systems.

ArcGIS ESRI Redlands, CA Market leader PC and workstation remarkable functionality many formats supported

ArcPad Mobile GIS Designed for GPS and PDA Developer package Uses Windows CE

AutoCAD MAP Windows all versions SQL DBF Access Extension to AutoCAD Menu-based Massive installed base Added grid, projection & topology support DB links good. 3D links good

GRASS First UNIX GIS Developed by Army Corps of Engineers UNIX functionality Many unique functions Free until recently Many data sets Baylor University now supports

IDRISI Developed at Clark University, Worcester MA Original in PASCAL, with open code Development uses a specialty Windows/DOS Spatial analysis/stats extensions

Maptitude Caliper Corporation Consultancy TRANSCAD and GIS+ Many network solutions Windows Import/Export Address matching

GeoMedia CAD software with GIS extensions Intergraph Corp, Huntsville AL Uses Windows NT Many parcel applications Web extensions, server tools etc.

MapInfo Based in Troy, NY Mapping functions Uses Visual Basic Many applications Favored for 911, field

New entry: Manifold

A variety of issues should be considered in system selection: n cost n upgrades n LAN configuration support n training needs n ease of installation n maintenance n documentation and manuals n help-line and vendor support n means of making patches n workforce

Selecting a GIS can be a complex and confusing process. n The intelligent GIS consumer should research, select, test, and question systems before purchase.

Coming next….. GIS in Action