Starting from Text Files

User Interface Graphic user interface –Mouse, buttons, windows, menus Commands-driven interface –Commands, parameters

Integration Spatial data –Coverage –Shapefile –Import/Export –Text files Attribute data –INFO –DBF –Text files

Generate GENERATE Arc: generate example2 Generate: circles Terminate input by entering END ID,X,Y,Radius: 201, 3, 7, 2.0 ID,X,Y,Radius: 202, 9, 4, 3.0 ID,X,Y,Radius: end Generate: quit

GENERATE: Examples Here is a listing of a file named PT.FILE. 1, 100, 100 2, 99, 112 3, 112, 119 4, 121, 98 5, 107, 102 END Arc: generate ptcov Generate: input pt.file Generate: points Generating points... Generate: quit Externalling BND and TIC... Arc: generate example7a Generate: copytics example4 Generate: points Enter points. Terminate input by entering END at ID,X,Y: prompt. ID,X,Y,{Angle},{Scale}: 601,3,7 ID,X,Y,{Angle},{Scale}: 602,9,7 ID,X,Y,{Angle},{Scale}: 603,5,4 ID,X,Y,{Angle},{Scale}: end Generate: quit Arc: generate example10 Generate: tics Enter Tics. Terminate input by entering END at ID,X,Y: prompt. ID,X,Y: 801,0,0 ID,X,Y: 802,0,10 ID,X,Y: 803,10,10 ID,X,Y: 804,10,0 ID,X,Y: end Generate: quit

GENERATE: More Examples In this example, the code automatically generates the polygon label point and adds the closing vertex. Arc: generate example8b Generate: polys Enter polygons. Terminate polygon by entering END at X,Y: prompt. Terminate input by entering END at ID,X,Y: prompt. ID,{AUTO | X,Y}: 701 X,Y: 3,9 X,Y: 4,5 X,Y: 8,4 X,Y: 9,7 X,Y: 6,9 X,Y: end (Label for ID 701 placed at 6.242,6.809) ID,{AUTO | X,Y}: end Generate: quit Arc: generate example9 Generate: polygons Enter polygons. Terminate polygon by entering END at X,Y: prompt. Terminate input by entering END at ID,X,Y: prompt. ID,{AUTO | X,Y}: 701,auto X,Y: 3,9 ; 4,5 ; 8,4 ; 9,7 ; 6,9 ; 3,9 X,Y: end (Label for ID 701 placed at 6.242,6.809) ID,X,Y: end Generate: quit

After GENERATE Use CLEAN and BUILD –Topology Precision –Whichever level in effect at the time of using Generate

UNGENERATE

GENERATE: In actual use Two parts: –Text file (coordinates) –DBF file (attributes) Use Generate with Text file to create a cover Use DBASEINFO to convert DBF to INFO table Use JOINITEM to join two parts together

UNGENEATE: example Arc: ungenerate point chcare chcare.ung

Import/Export Arc: Export Cover Roads Roads (generates exported file roads.e00) Arc: Import Cover Roads Roads1 (generates coverage roads1) Arc: Export Grid DEM DEM Arc: Import Grid DEM DEM1

Exported coverage: a single file LAB TOL LOG BND PAT TIC …

Assignment From ArcDoc, answer: –How to “generate” a coverage with annotation in it? –How to “generate” curves? –How to “generate” a fishnet? Using the steps demonstrated in class and data files downloaded, create coverages for welfare, company, bus, and road Using ArcGIS, create a map that shows all coverages. –Export the map into a graphic file and then to me as the submission.

Spatial Data Creation and Spatial Data Conversion

Spatial data considerations Converting an existing digital dataset into GIS database Creating from ground zero: –Georeferencing a paper map –Tracing geographic features –Adding attributes –Building topology –Validating data –Creating metadata

Sources of data

Capturing data From hardcopy spatial data –Scanning Taking a digital picture of the map –Digitizing Tracing the map with a tracing device –Heads-up digitizing Combination of scanning and digitizing

Scanning Creates a raster image of a hard-copy map The raster image can be vectorized –ArcScan, ARC GRID Units: inches, centimeters, pixels Requires georeference

Tablet digitizing Produces a vector coverage Unit: digitizer unit (e.g., inches) Requires georeference Can use ADS, ArcEdit Can be rasterized: ARC GRID

Heads-up digitizing Combines scanning and manual digitizing Maps are first scanned, georeferenced, and then displayed on screen for tracing features Pros –Fast, –allowing error-correction, Cons –Possible errors

Coordinate space

Topology Independent of coordinate space A result of actual relative locations of real-world geographic features

Data automation Accuracy of spatial data and attributes affect the accuracy of analysis results Data automation process is critical in implementing any GIS –No data, –No analysis of data, –No results

Automation considerations Which method of data capture will be used? How will data be referenced to the real world? Will BUILD or CLEAN be used to construct topology?

Georeferencing with a master coverage Master coverage –A georeferenced coverage –Used to georeference all other spatial data in database –Coordinates in the master coverage are normally in real-world coordinates already –Created by Type up/import coordinates into a dbase file Use CREATE to initiate an empty coverage Use TABLES/ADD to add coordinates

Master coverage You can use ArcInfo to copy the tics from the master coverage before digitizing, or You can use the master tics to move coverage features to a different coordinate space after digitizing.

Digitizing tolerances To reduce errors –Weed tolerance –Arc snap –Node snap –Arc intersect

Constructing topology Record spatial relationships Minimize data redundancy

BUILD and CLEAN BUILD –Creates topology for points, arcs, polygons, and annotation –Does not move/delete features –Fails when encounters intersections BUILD {POLY|LINE|POINT|ANNOtation} CLEAN –Creates topology for arcs and polygons –Moves or deletes features –Alters coordinates of features CLEAN {out_cov} {dangle_distance} {fuzzy_tolerance} {POLY|LINE}

Tolerances used with CLEAN

Converting Vector Data

Digital vector data

Evaluating digital data

Accessing digital data Before obtaining digital data, be sure you know its format and that you have a device for reading it.

Georeferencing converted data CAD data – no georeferencing GIS data –Right map projection? –Correct topology? Transformation –Aligns tics to matching tics in a georeferenced coverage

Transformation Converts coverage coordinates from one coordinate system to another through –Translation (shift) –Rotation –Scaling TRANSFORM

RMS error

Summary Sources of data Tools for data conversion Data automation BUILD and CLEAN Georeferencing spatial data TRANSFORM

Converting Vector Data

Digital vector data

Evaluating digital data

Accessing digital data Before obtaining digital data, be sure you know its format and that you have a device for reading it.

Georeferencing converted data CAD data – no georeferencing GIS data –Right map projection? –Correct topology? Transformation –Aligns tics to matching tics in a georeferenced coverage

Transformation Converts coverage coordinates from one coordinate system to another through –Translation (shift) –Rotation –Scaling TRANSFORM

RMS error

Summary Sources of data Tools for data conversion Data automation BUILD and CLEAN Georeferencing spatial data TRANSFORM