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How To: Create a polygon coverage from DFAD data

Summary

Instructions provided list the sequence of steps to convert a DFAD file to a polygon coverage.

Procedure

DFAD data is a set of manuscripts from which the DFADARC creates pairs of coverages. The new coverages will be named as followed with 'n' being the number of manuscripts in the original DFAD file.

DS01L and DS01P
DS02L and DS02P
...
DS0nL and DS0nP

Each 'L' coverage contains line and point features that relate to the <cover>.ACODE and <cover>.XCODE attribute files that are created in the same workspace. The ACODE file can be joined to the AAT based on the <cover>-ID in the AAT and the FACODE item in the ACODE. The XCODE file can be joined to the PAT based on the <cover>-ID in the PAT and the FACODE item in the XCODE.

The 'P' coverage contains area features and the attributes of these features are stores in the <cover>.PCODE file. Area features in a DFAD file may be overlapping or discontiguous and are only represented as chains of arcs when first converted. The REGIONCLASS command can be used to create overlapping or discontiguous area features from these lines.

  1. Convert the DFAD file to a new ArcInfo workspace.

    Code:
    Arc: precision double double

    Usage: DFADARC <in_dfad_file> <out_workspace>
    Arc: dfadarc dfad1 tempwork

    Data Set #1...
    DFAD Level 1-C Manuscript
    WAG (WAC) number: 405 Series 200 cell: 22 Series 50 cell: 14
    Data Set reference number: G18 013 Edition: 01
    Compilation date:
    Geographic extent: (00 00 00.0 N, 000 00 00.0 E) SW
    (01 00 00.0 N, 001 00 00.0 E) NE
    Security Classification: UNCLASSIFIED LIMITED DISTRIBUTION

    End of DFAD file.
    Done converting dfad1.

  2. Change workspaces and list the coverages.

    Code:
    Arc: workspace tempwork
    Arc: lc
    Workspace: C:\TESTING\DFAD\TEMPWORK

    Available Coverages
    -------------------
    DS01L DS01P

  3. The chain of arcs which formed enclosed area features in the original DFAD file will be coded with unique values stored in the <cover>-ID item in the AAT.

    Code:
    Arc: items ds01p.aat

    COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC
    1 FNODE# 4 5 B -
    5 TNODE# 4 5 B -
    9 LPOLY# 4 5 B -
    13 RPOLY# 4 5 B -
    17 LENGTH 8 18 F 5
    25 DS01P# 4 5 B -
    29 DS01P-ID 4 5 B -

  4. Use REGIONCLASS to create region features from the closed chains of arcs. The new region features will be stored in a region subclass and the original <cover>-ID values will be stored in the FACODE item in the region attribute table.

    Code:
    Usage: REGIONCLASS <in_cover> {out_cover} <out_subclass>
    {in_region_item} {out_region_item} {selection_file}
    {MULTIRING | SINGLERING}

    Arc: regionclass ds01p ds01reg land ds01p-id facode
    (Re)building nodes...
    Grouping arcs for regions...
    3 preliminary region(s) appended to subclass land.

  5. CLEAN the coverage to create polygon and region topology.

    Code:
    Usage: CLEAN <in_cover> {out_cover} {dangle_length}
    {fuzzy_tolerance} {POLY | LINE}

    Arc: clean ds01reg # 0.01 0.01 poly
    Cleaning C:\TESTING\DFAD\TEMPWORK\DS01REG
    Checking regions...
    Sorting...
    Intersecting...
    Assembling polygons...
    Re-building AAT...

  6. Join the <cover>.PCODE to the region attribute table based on the FACODE item which exists in both tables.

    Code:
    Usage: JOINITEM <in_info_file> <join_info_file>
    <out_info_file> <relate_item> {start_item}
    {LINEAR | ORDERED | LINK}
    Arc: joinitem ds01reg.patland ds01reg.pcode ds01reg.patland
    facode facode

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