How To: Prepare ArcInfo coverages for conversion to DFAD format
Steps to prepare ArcInfo coverages for conversion to DFAD manuscript format. Useful AMLs are referenced as well.
- All coverages in the workspace must be named DSnnnL or DSnnnP.
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- Each DSnnnL coverage which has been built for POINT (BUILD POINT) must have an associated .XCODE INFO file with specific item definitions.
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- Each DSnnnL coverage which has been built for LINE (BUILD LINE) must have an associated .ACODE INFO file with specific item definitions.
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- The DSnnnP coverage arcs must encompass closed areas, and the arcs for a given area must all have the same COVER-ID. Borders between areas must have an arc for each area.
Area borders should be two arcs directly on top of each other and sharing the same vertex coordinates (referred to as 'coincident arcs'). You can use COPY PARALLEL 0, in ARCEDIT, to create coincident arcs and SELECT BOX WITHIN to select both coincident arcs for COVER-ID updates.
Arcs of an area completely enclosed by another area must have higher COVER-IDs than arcs of the surrounding area.
- Each DSnnnP coverage must be built for LINE (BUILD LINE) and must have a .PCODE INFO file with specific item definitions.
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- DSnnnP coverages must contain at least one record in their .PCODE file with an FACODE equal to 1.
- The first record in the DSnnnP.AAT must have a cover-ID equal to 1 and represent a minimum bounding rectangle (MBR) for all data that exists in the stand-alone DSnnnP coverage or a the DSnnnL - DSnnnP pair.
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- For a given DSnnn designation, if there is only an L coverage, then a DSnnnL.DES INFO file must be created. If there is only a P coverage, then a DSnnnP.DES must be created. If both coverages exist, then either a DSnnnL.DES or DSnnnP.DES must be created.
<a href='http://support.esri.com/en/knowledgebase/techarticles/detail/15946' target='_blank'>How To: Define a .DES INFO file for ARCDFAD input coverages</a>
- The coordinate system for all coverages in the DFADARC input workspace should be PROJECTDEFINE'd to:
Projection - GEOGRAPHIC
Units - DD
Spheroid - WGS84
- The DSnnnL-ID values in the DSnnnL.PAT and DSnnnL.AAT must be unique. They must not use ID values that exist in the DSnnnP.AAT. For example, if the point IDs in the DSnnnL.PAT are 1,2,3,4. Then the DSnnnL.AAT and DSnnnP.AAT must use IDs other than 1,2,3,4.
- The features from the L and P coverages cannot total more than 16383. This limit is set by the DFAD format specifications.
- An individual feature cannot exceed 8191 coordinates. This limit is set by the DFAD format specifications.
An individual feature is a set of arcs that define a single output DFAD feature. For example, if an area feature is composed of ten coverage arcs, each arc having the same COVER-ID, this group of arcs is considered a single DFAD feature. The total number of nodes and vertices among these ten arcs cannot exceed 8191. For an area feature, if there are more than 8191 coordinates defining the feature, it must be divided into 2 separate features, each referencing a separate FACODE.
The ArcInfo DFAD translator supports DFAD levels 1, 2, 1-C, and 3-C only. Check with your data provider to determine what DFAD level you have. See Related Information to find out how to obtain the DFAD specifications.