More dimensions (Z for height, T for time) also possible, but harder. Typically represented as a two-dimensional X-Y array. Many natural features are very hard logically to delineate (because consequence of continuous processes). Discrete objects / legal boundaries versus Natural gradients. Raster data model is a very efficient representation inside digital computers. Vector data model, particularly with polygons, is complex ("simple" overlay requires many computations). In an analysis with dozens of layers, can spend as much time on cleanup as analysis. Manning's Ideas & Methods Revisted and Popularized in 1960s by Ian McHarg (Penn) and Carl Steinitz (Harvard) characteristics might be "medium good" or "pretty bad" for intermediate cases. characteristics might be "bad" in which case overlap areas are "unsuitable". characteristics might be "good" in which case overlap areas are "suitable". Use overlays of maps to determine areas where characteristics overlap used light tables and hand tracing for spatial analysis. mapped natural resources by survey (no airphotos!). #VECTOR OR RASTER FOR NATURAL LANDSCAPE HOW TO#
How to implement these ideas in a predigital world? (not easy!)
Differed from "City Beautiful movement" which emphasized monumental civic centers and public buildings. importance of parks: "the cities that are best designed have about one-eigth of their area in parks and about one acre to 75 people." (Manning 1919). resource-based planning (natural characteristics should influence city form) "multiple neighborhood-based centers determined by available resources". wrote first "National Plan" advocating conservation areas as well as development. very prolific (1700 projects over career) and influential. Warren Manning, student of Frederick Law Olmstead, active early 20th century Raster Data Models (model properties of uniformly spaced grid cells) Historical Motivation General Concept of Suitability Analysis (i.e., appropriate land use based on characteristics of land) Web Feature Service) Geographic Markup Language (GML) for xml-based Services and Application Programming Interface(Web Mapping Service and Standards: SDTS (spatial data transfer standard forĪrchival file format) Open Geospatial Consortium protocols for web. Use their own proprietary data formats, making for a Babel of GIS data Other GIS packages (MapInfo, Intergraph, TransCAD, Maptitude). Relies on a heavy-duty RDBMS such as Oracle. Retrieved dynamically from a database server. Coverages must be moved using ArcGIS (ArcCatalog), not operating system file. This shared info directory impedes data management. In "Info" tables in a shared info directory Database tables for all coverages in the workspace are stored. 
A workspace typically contains several coverage directories.Geometry includes topological relationships among features.One directory per layer containing its geometry files (.Shapefiles are easily moved or copied within the OS just copy.Topological relationships are not stored in the layer, but computed.A closed object with an interior and exterior.Extra points between the nodes-vertices-may add shape to the line.Built from at least two points at the ends of the line: the nodes.Vector Data Models for GIS Up to now - Vector Data Models (model boundaries of spatial features) Today - Raster-based Spatial Analysis Review Raster vs.
Then, one more lab (on web mapping and geospatial services ).Lab #7 due the following Monday - raster-based spatial analysis.Lab #6 due next Monday - vector-based spatial analysis.
Part I of Homework Set #2 due today (Part II due Nov. Spatial Data Models: Spatial Analysis II (Raster Models) Octobased on materials by Michael Flaxman, Joseph Ferreira, Thomas H. Spatial Data Models and Spatial Analysis IIġ1.520: A Workshop on Geographic Informationġ1.188: Urban Planning and Social Science Laboratory
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