Introduction to GIS GIS/CAD5

CAD – Computer Aided Design GIS – Geographic Information System CAD – drawing, editing, construction, project visualisation - 2D and 3D GIS - mostly 2D - mapping, information collection, spatial analyses, interpretation

GIS - essential terms Map – consists of layers and symbolisation Layer – set of single-type information - parcels, streets, buildings, contour-lines, … also called as feature class Feature – a single map object - building, pond, … Attribute – a single characteristics of feature - height, area, type, …

Map – consists of layers

Layers geometryVectorRaster Point Line Polygon Layers in GIS usually can not contain more than one geometry type One GIS layer normally corresponds to one file

Feature – single object of a layer GIS feature consists of 2 parts: Layer is represented as TABLE Features is represented as ROW of the table Geometry Attributes

Attributes – characteristics of the features Attributes are represented as COLUMNS of the table Geometry Attributes

Understanding to Drawings and Layers 1. CAD Drawing = File consists of layers data and other information at one file Drawing (file) Layer Drawing (file) Layer Reference layer

Understanding to Drawings and Layers 2. GIS Layer = File Project = (map) File consists of reference to layers information on selection and symbolisation layout graphics (legend, titles, etc.) Layer (file) Project (file) Layer (file) Project (file)

GIS data formats Note: SW GIS normally can read CAD files! ESRI Shapefile (SHP) – GIS commercial standard GML – XML based standard (not much supported) ESRI Geodatabase (GDB, MDB) TIN (vector surface) GRID (raster data) GeoTIFF, JPG, PNG, … Rasters must have coordinate system reference!

Layers – data sources and storage Files – GIS formats (shapefile, geodatabase file, rasters) – CAD formats (DXF, DWG, DGN) On-line WWW services – Raster services (WMS) – Vector services (WFS) Database tables (Oracle, PostGIS, …)

Useful links: – ESRI vendor – ESRI vendor – Czech Geoportal – Prague Geoportal