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Data Conversion

Data Conversion. Conversion Commands. From Interchg file format • To Interchange file format import – export From Shapefile • To Shapefile shapearc – arcshape From Census data • To Census data tigerarc – arctiger tigertool From another GIS • To another GIS

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Data Conversion

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  1. Data Conversion POEC 6382 Applied GIS Software

  2. Conversion Commands • From Interchg file format • To Interchange file format • import – export • From Shapefile • To Shapefile • shapearc – arcshape • From Census data • To Census data • tigerarc – arctiger • tigertool • From another GIS • To another GIS • dlgarc (.dlg) – arcdlg • dxfarc (.dxf) – arcdxf • igdsarc (.dgn) – arcigds • igesarc (.ige) – arciges • etakarc ( • From DBASE to INFO • To DBASE from INFO • dbaseinfo – infodbase There are many others—go to ArcDoc under “Data Conversion”for details POEC 6382 Applied GIS Software

  3. Arc Interchange File Format Interchange File Format (suffix .e00) • permits easy transportation to another platform running Arc/INFO. • An interchange file contains all coverage information and appropriate INFO file information in a fixed-length, ASCII format. • Can drag and drop an interchange file, as well as download it from the internet. • EXPORT - converts a coverage, file or other supported data set to interchange file format • Arc: export cover cities cities (prefix only, suffix will be added) • Will convert a coverage named cities to an export file, cities.e00 • IMPORT - recreate the coverage, file or other supported data set from an exported interchange file. • Arc: import cover cities cities • converts an interchange file cities.e00 to a coverage named cities • The utility IMPORT71 which comes with ArcView can also be used to convert .e00 files to coverages, so you don’t have to have ArcInfo to use .e00 POEC 6382 Applied GIS Software

  4. COVERAGE TO SHAPE • ARCSHAPE - writes feature attributes or INFO records to a new shape data file • ARCSHAPE <in_cover> <in_feature_class> <out_shape_file> • SHAPEARC - writes shapefile spatial and attribute information to an ARC/INFO coverage. • shapearc <in_shape_file> <out_cover> {out_subclass} • Problems with polygons - Shape polygon features are converted into REGIONS because “there is no way to insure that polygon shape features do not overlap” (i.e., shape files do not have topology). If polygon topology is required, provide an out_subclass name so that your attributes will be stored in the region subclass table which will be named: <out_cover>.pat{out_subclass}. Then the REGIONPOLY command is used to recreate the polygons. POEC 6382 Applied GIS Software

  5. A Note on Regions • A way to represent more complex features • The islands of Hawai (multiple polygons) as one region • House, garage, barn building footprints at one address as one region • States of US as 50 regions, each with their counties as inside polygons (outer boundary is then the same for states and its border counties) • Overlapping areas, such as wildlife habitats overlapping with land use types • Regions are handled as a special “feature class” (or subclass), just as arcs, polygons, etc. are feature classes • There are about 25 commands for creating and processing regions! • Because shape files are not fully topological, ArcInfo does not know if polygons overlap, therefore it creates regions when converting shapefiles with polygons to coverages • REGIONPOLY is the command which converts regions into polygons POEC 6382 Applied GIS Software

  6. REGIONPOLY • REGIONPOLY • converts a regions subclass into a polygon coverage and creates an INFO table containing overlapping region information. • creates the polygon coverage by performing a REGIONCLEAN on the region coverage to eliminate unnecessary polygons. RESELECT is then used to select only those polygons associated with the region subclass. DROPFEATURES is used to drop region subclasses from the out_cover. If the <in_cover> does not have label points, CREATELABELS is used to add label points to the <out_cover>. • REGIONPOLY adds some extra fields (subclass, subclass#, rings_ok, rings_nok) to your .pat. To get rid of these use DROPITEM. • REGIONPOLY <in_cover> <out_cover> <in_subclass> {out_table} POEC 6382 Applied GIS Software

  7. Steps for SHAPEARC with polygons Example for shape file named TRACTS.shp (a shape file with this name containing census tracts for Plano is in the p:\p6382\ex4 folder) • SHAPEARC <in_shape_file> <out_cover> {out_subclass} arc: SHAPEARC tracts tracts class arc: LC (list of coverages should include TRACTS) arc: DIR INFO (note that there is no tracts.pat, but there is a tracts.patclass • CLEAN <in_cover> {out_cover} {dangle_length} {fuzzy_tolerance} { POLY | LINE} (this will recreate the polygons) arc: CLEAN tracts tractsC .01 .01 poly (always give cleaned version a new name) arc: DIR INFO (now have a .pat file) arc: ITEMS tracts.pat (however, no attribute data) • REGIONPOLY <in_cover> <out_cover> <in_subclass> {out_table} arc: REGIONPOLY statesc state class class.tbl (class.tbl contains info about the old regions) arc: ITEMS tracts.pat (now have attribute data, but extra junk variables) • DROPITEM <in_info_file> <out_info_file> {item … item} (this is optional) arc: DROPITEM state.pat state.pat subclass# rings_ok rings_nok arc: ITEMS tracts.pat (now have just the data items we wanted) (Note: ArcToolbox and ArcCatalog conversions incorporate all of the above steps) POEC 6382 Applied GIS Software

  8. Conversion Commands - Tiger/LINE • TIGERARC - converts from Census TIGER/Line files to Arc/INFO format • ARCTIGER - converts from Arc/INFO into TIGER/Line format • TIGERTOOL - runs the TIGERARC command and then processes the output by combining area point features and line features into one integrated polygon coverage. POEC 6382 Applied GIS Software

  9. CONVERSION FROM OTHER GIS dlgarc - Converts from USGS Digital Line Graph (DLG) format to Arc/INFO format arcdlg - Converts from Arc/INFO to DLG dxfarc - Converts Autocad DXF (digital exchange format) to Arc/INFO dxfinfo - Describes the contents of a DXF file arcdxf - Converts from Arc/INFO to DXF format igdsarc - Converts from Intergraph’s Interactive Graphics Design Software (IGDS) and MicroStation Design format to Arc/INFO. --these files have a .dgn extension igdsinfo - Describes contents of IGDS file arcigds - Converts from Arc/INFO to IGDS igesarc - Converts from Initial Graphics Exchange Specification (IGES) to Arc/INFO arciges - Converts from Arc/INFO to IGES etakarc - Converts from Etak MapBase file to Arc/Info There are many others—go to ArcDoc under “Data Conversion”for details POEC 6382 Applied GIS Software

  10. Conversion from Other GIS (e.g .dxf) LAYERS • DXF format files, for example, may have up to 999 “layers” of vector data. This is typical of CAD files. • Use the command dxfinfo (for .dxf) or igdsinfo ( for .dgn) to get list of layers • shapefiles and coverages typically contain only one type of data—for example, streets, railroads, and hydrologic features would each be a separate coverage • However, it is possible to store multiple line and point features in a single coverage, using an item field (dxf-layer) to differentiate the layers. • Generally, when converting CAD files (such as .dxf), you have two choices: • Convert all layers to one coverage and use an item variable to differentiate them (use the $REST option; the item dxf-layer will differentiate the layers) • Convert each layer to its own coverage, by either • Create one coverage as above and then reselect on dxf-layer to re-create separate ones • Use dialog in dxfarc (or ArcToolbox wizard) to convert each layer to separate coverages POEC 6382 Applied GIS Software

  11. Conversion from Other GIS (e.g. .dxf)(contd.) ATTRIBUTE DATA • Some converted coverages (for example, those from dxf and dgn formats) have INFO files containing attributes for the coverage that are not automatically joined to the coverage. • These INFO files can be seen with Arc: dir info command. • The attributes are stored in • <cover>.acode INFO file for feature class arc • <cover>.pcode INFO file for feature class poly • <cover>.xcode INFO file for feature class point. • Use the JOINITEM command to join the INFO file to the cover, using <cover>-id as the <relate_item> • Note that TIGERTOOL and the conversion wizards in ArcToolbox do the joinitem for you POEC 6382 Applied GIS Software

  12. AutoCAD .dxf Example Key83.dxf, the file to be converted, is in p:\poec6382\ex4  &watch dxfarc.wat (useful for viewing output from dxfinfo below) Display the dxf file—note the multiple layers Arc: ap Arcplot: mape dxf key83.dxf Arcplot: dxf key83.dxf Arcplot: quit Display info about dxf file layers—again, note the mutiple layers Arcplot: dxfinfo key83.dxf (provides info about the dxf layers— does not covert to INFO) Convert Arc: Dxfarc key83.dxf Enter the 1st layer and options: $rest (converts all layers) View Results arc: dir info key83.acode (arc features) key83.xcode (point features—text annotation in this case) Note: no .aat or .pat file) POEC 6382 Applied GIS Software

  13. AutoCAD .dxf Example (contd) Join Attribute data arc: build key83 lines Arc: dir info (there is now an .aat file.) Arc: items key83.aat (however, no attribute data in .aat file) Arc: list key83.acode (this is where the attribute data is --note the dxf-layer variable which identifies the layer --use dxf-layer to split into separate coverages arc: joinitem key83.aat key83.acode key83.aat key83-id (adds attribute data to .aat file)  Separate out the city layer arc: reselect key83 key83city lines Enter a logical expression Ø      reselect dxf-layer = ‘CITY’ Ø      do you wish to re-enter ? n Ø      do you wish to enter another expression? n arc: clean key83city arc: build key83city poly arc: describe key83city Display key83city in arc • Arc: ap • Arcplot: mape key83city • Arcplot: polys key83city POEC 6382 Applied GIS Software

  14. INTERGRAPH .dgn Example • Get information: IGDSINFO <in_igds_file> Arc: igdsinfo base.dgn\ (Provides the layer names you will for the igdsarc command to process selected layers.) • Do conversion: IGDSARC <in_igds_file> <out_cover> Arc: igdsarc base.dgn base • IGDSARC will prompt you for the information necessary to perform the IGDS conversion. You will be prompted for the layer names and entities of each IGDS layer to be processed. The format of the interactive dialog used by IGDSARC is as follows: Enter layer names and options (type END or $REST when done): ================================================== Enter the 1st layer and options: $REST Do you wish to use the above layers and options (Y/N)? Y POEC 6382 Applied GIS Software

  15. INTERGRAPH .dgn Example (contd.) • Check if coverage has been created: Arc: lc • Look at files created Arc: dir info (will see .aat and .acode info files) • Describe the coverage -- see if topology needed. • Build topology for lines or polygons, depending on cover • Join the acode attributes to the .aat, or the xcode attributes to the .pat POEC 6382 Applied GIS Software

  16. Notes on ArcToolbox Converting Shapefiles • When converting shapefiles with polygons, ArcToolbox runs shapearc, regionpoly and dropitem, thus creating “ready to use” feature attribute table Converting CAD files • CAD files displayed in ArcCatalog have two icons: • “triple box” (top) icon contains point, arc, polygon datasets • Use this for conversions • “single box” (lower) icon is drawing file, and will display all layers • When converting, convert each dxf-layer separately • .acode (for arcs), .pcode (for polys) and .xcode (for point and annotation) files are created, and they are also automatically joined to the feature attribute tables. POEC 6382 Applied GIS Software

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