Export into E00 format. A recommended format for exporting GRASS vector data is the ESRI E00 format. It is performed by v.out.eQQ, which writes a vector map to an ARC/INFO line/polygon coverage. We can export the roads map of the Spearfish data set as follows:

v.out.eOO roads mapset=PERMANENT out=roads.eOO

It is required to specify an output name, otherwise the E00 data stream will be written to standard out (stdout). The file is stored in the current directory.

Export into UNGENERATE format. Export of GRASS vector maps to ESRI UNGENERATE file format is possible with v.out.arc. A GRASS vector file to be exported to ARC/INFO must either contain only linear features (line vectors) or only area features (polygon vectors). The vector type, line or polygon has to be specified. To inspect a vector file, use v.info. As an example we export the roads vector map by:

V.info roads

v.out.arc roads type=line arc prefix=roads

Export into GRASS ASCII vector format. The module v.out.ascii allows us to export a GRASS vector map to GRASS ASCII format. As an intended exception, the exported file will be stored within the LOCATION in a subdirectory dig ascii/ and not in the current directory. The category labels are stored in ASCII format at dig cats/ (however, the file is identical to the binary GRASS binary format). The label points file will be found in the directory dig att/ which is also identical to the GRASS binary format.

Export into SDTS format. To export a vector map to SDTS data set conforming to the Topological Vector Profile (TVP) we can run the module v.out.sdts. The usage is very simple:

The parameter output is a prefix for the SDTS output files which must be 4 upper-case characters and/or digits. The resulting files are stored in the subdirectory named according to the output parameter, generated in the current directory or a directory defined with path parameter. The output data set is in the mandatory ISO 82II (FIPS 123) format. When desired, the ISO 82II/SDTS output files can be inspected with m.sdts.read. Two flags are available: -a restricts the output to areas while omitting lines, the flag -m accesses a user-defined metadata file. This file is typically, but not necessarily, created with v.sdts.meta. SDTS data sets are required to contain 5 different data quality report modules, for lineage, positional accuracy, attribute accuracy, logical consistency, and completeness. When v.out.sdts is run, it searches in the

users MAPSET dig misc directory for appropriate files, one for each module, containing narrative text in ASCII format as written by v.sdts.meta, a TclTk based application with menu entries to supply the metadata information. If metadata files generated with v.sdts.meta is found, they are converted to SDTS/ISO 8211 format and added to the export data set; warning messages are displayed if any data quality modules are missing.

In addition to the files created by v.out.sdts, every SDTS transfer must contain a README file. This file is not generated by v.out.sdts, and must be created by hand (see the manual page for this command).

Export into DXF format. To export GRASS vector files to DXF format, the module v.out.dxf can be used. The usage is very simple, as we demonstrate with the roads map again:

v.out.dxf roads out=roads.dxf

The DXF file is written to the current directory.

4.3. SITES DATA

In addition to the vector format, features that are spatially referenced to a single point can also be stored in the GRASS site format. Note that other GIS software may not support handling of site data separately from vector data.

4.3.1 GRASS sites data model

The multi-dimensional, multi-attribute ASCII sites format includes a coordinate entry followed by a category (with a # as prefix), optional floating point attributes (% as prefix), and optional character string labels (@ as prefix). All character strings that include a space must be enclosed with quotes . The coordinates are separated by a vertical bar while the rest of the fields are separated by a space. The format in general is as follows:

east I north I [z [ I . . . ] ] [#cat int] [%at fp [%at fp...]]\

[@at str [%at str...]]

The GRASS sites model also supports an optional header which describes the data stored in the sites file. Example of such a header is as follows:

namemyname

desclSoil chemical data time I 15 Jan 1994

labels I east north elevation ID pH Nitrogen formi I I#%%

The following example of soil profile data entry includes location coordinates easting and northing, site ID as an integer category, pH value as a floating point attribute, and character strings describing the soil texture and land cover. In our example, the file header includes only two lines describing the name of the file and the label for each field:

name I Soil data

label I east north ID pH texture vegetation 3567000 15787000 1*1 %4.2 @ sandy soil @ forest

For points in geographical coordinates, the header and data entry may looklike this:

labels I longitude latitude ID elevation 75:33:55.34WI 33:44:59.2 IN I#1 %22 5.2

4.3.2 Import of sites data

There are several approaches to import a sites map layer. Site data can be directly entered into the GRASS DATABASE by copying an ASCII file in the prescribed format into the site lists/ subdirectory in the LOCA-TION/MAPSET directory, or the data can be imported from a number of supported formats (e.g., CSV, ArcView, dBase, MapInfo). Finally, the points can be digitized from a map.

GRASS provides modules to import point data in various formats such as s.in.mif for MapInfo point data, s.in.shape for ArcView, s.in.atkisdgm for German ATKIS (elevation data transfer format), and s.in.dbf for the dBase data. Site data measured by GPS can be imported as sites using s.in.garmin.sh or as vector data using v.in.garmin.sh and then converted to sites using v.to.sites. Timestamps or time ranges are supported with a date parameter for s.in.ascii and s.in.dbf. Please refer to Section 5.1.4 how to define a timestamp or time range.

Importing ASCII tables. Point data in ASCII format can be imported directly with s.in.ascii. The data should be arranged as east north value:

3246000.0 5877000.0 23.0 3246012.5 5877012.5 24.4 3246025.0 5877025.0 22.3

Then, they can be imported as follows:

s.in.ascii sites=mygrasssites input=myasciisites

Optionally, you can define a timestamp for the map (parameter date). Note that s.in.ascii will insert a file header and a category number (ID) after