## NAME

v.out.sdts - Creates an SDTS dataset conforming to the Topological Vector Profile from a GRASS vector map layer.
(GRASS Vector Data Export/Processing Program)

## SYNOPSIS

v.out.sdts
v.out.sdts help
v.out.sdts [-am] input=name [path=name] output=name

## DESCRIPTION

v.out.sdts creates an SDTS dataset that conforms to the requirements of both the federal Spatial Data Transfer Standard and the SDTS Topological Vector Profile. It creates the dataset from the files associated with a vector map layer which is specified by the user. The files that make up the SDTS dataset are output to the current directory, unless otherwise specified by the user (with the path parameter). The output dataset is in the mandatory ISO 8211 (FIPS 123) format; the ISO 8211/SDTS output files can be inspected with m.sdts.read.

## COMMAND LINE OPTIONS

### Flags:

-a
  transfer Lines of "AREA type" only; omit Lines of "LINE type" from output SDTS dataset.
-m
  access user-defined metadata file. This file is typically, but not necessarily, created with v.sdts.meta. See the discussion of SDTS data quality files and metadata below.

### Parameters:

input=name
  name of vector map layer from which the SDTS dataset wil be created.
path=name
  full path to location for placement of output SDTS dataset. Path must exist and be writable by the user. If path is not specified, dataset will be output to the current directory.
output=name
  four-character string to be used as prefix for each of the output SDTS files. Can be any combination of letters and digits, although letters must be upper-case.

## LINE TYPES IN GRASS AND SDTS

GRASS makes a distinction between types of lines, between those that are edges of areas or polygons and those that are not. GRASS handles these types different topologically: AREA type lines carry pointers to left and right polygons, but LINE type lines carry no such pointers.

The SDTS Topological Vector Profile, however, does not distinguish line types, and does require that ALL lines carry left and right polygon references. This has meant that during the export process topology-building algorithms are applied to construct the missing topology that SDTS requires. A potential problem arises, however, with the transfer of object attributes in certain circumstances. E.g. if a polygon in GRASS is bisected by a line of type LINE, the resulting SDTS dataset will contain two polygons where only one existed in GRASS: should both these polygons be assigned the attribute of the original, now non-existent polygon? The "-a" option, which transfers only AREA type lines, works around this problem.

## SDTS REQUIREMENTS: DATA QUALITY REPORTS

SDTS datasets 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 user's mapset's dig_misc directory for appropriate files, one for each module, containing narrative text in ASCII format. If found, they are converted to SDTS/ISO 8211 format and added to the export dataset; warning messages are displayed if any data quality modules are missing.

Data quality reports can be created, and installed in the proper location under dig_misc, with v.sdts.meta.

## OTHER METADATA

When v.out.sdts is run, if the "-m" flag is set, the program searches in the dig_misc directory for a supplementary metadata file for the map layer being transferred. If found, its contents are incorporated in the SDTS dataset. This file can be created and installed with v.sdts.meta; for details see the man page for this program.

## SDTS REQUIREMENTS: THE 'README' FILE

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. It should contain:

  "volume name [if appropriate], date, a list of SDTS transfers (if more than one), and then for each SDTS transfer: a list of subdirectories and non-SDTS files, if approriate, the file name of the Catalog/Directory module, where it can be found, and an explanation that this file and all other SDTS files are in ISO 8211 format, and that the Catalog/Directgory module carries a complete directory to all other SDTS ISO 8211 files comprising the SDTS transfer, notes about any non-SDTS adjunct/auxiliary files, a brief explanation of the spatial domain, the purpose, authority (FIPS 173), source (e.g. agency name) and contacts within the source organization...." (SDTS, IV: Topological Vector Profile, 6.10).

  ## GRASS ATTRIBUTES IN THE SDTS DATASET

  The SDTS dataset produced by v.out.sdts contains two attribute module files. One, containing attribute module "AP00", stores global attributes, i.e., metadata items applicable to the entire transfer (most are derived from the dig file header). The second holds attribute module "AP01", and contains records with two fields: ATTR_NUM contains dig_att integer values; and ATTR_LABEL contains the corresponding labels or descriptions from the dig_cats file.

  ## RESTRICTIONS

  Currently, the user can only create an SDTS dataset from a single vector map layer in his or her mapset at a time.

  ## SEE ALSO

  m.sdts.read, v.in.sdts, v.out.sdts, v.sdts.dp.cp, v.sdts.meta.cp, v.sdts.meta

  ## AUTHORS

  David Stigberg, U.S.Army Construction Engineering Research Laboratory
  Tin Qian, University of Illinois

  Last changed: $Date: 2002/01/25 05:45:35 $