10/14/09

The NCGMP09 database design specifies certain information regarding geologic map cartography.  In order to help you evaluate that design, we include a draft ESRI line style based on the "FGDC Digital Cartographic Standard for Geologic Map Symbolization" (http://ngmdb.usgs.gov/fgdc_gds/).

The NGMDB project continues to work with ESRI on their implementation of the FGDC standard, in which the symbols are built as Cartographic Representations.  However, Cartographic Representations are applicable only to ArcGIS 9.3 and above, and they employ a different method of symbolization that is not yet compatible with the NCGMP09 database design.  To help evaluate NCGMP09, we include here a style file that contains an (albeit limited) implementation of the FGDC standard.  This style file was built by Taryn Lindquist in ArcGIS 8.3 several years ago during the development of technical specifications for the FGDC line symbols, in order to test the symbology in Arc.  It was, therefore, never intended for widespread adoption and use in its current form.  But bearing in mind the caveats (below), it may have some immediate utility, especially for evaluating NCGMP09.

Comments about the style file should be directed to Taryn Lindquist and Dave Soller (USGS), at mapsymbol@flagmail.wr.usgs.gov.


CONTENTS:

-  draftFGDCGeology1.style -- style file containing many of the lines in Sections 1-5 in the FGDC standard

-  symdmpln=draftFGDCGeology1.pdf -- symboldump of the lines in the style, as a PDF file

-  standard_pages_secs1-5.pdf -- contains line symbol numbers and specs for draftFGDCGeology1.style

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CAVEATS (provided by Taryn):

-- The dash/gap lengths are pretty much "up to spec" according to the FGDC standard, with minor modifications in order to plot correctly in Arc software.

 -- Line symbol parts such as thrust teeth, queries, etc., were gathered from existing (at that time) ESRI marker/font files -- in other words, new TrueType fonts were not generated for the various parts.  What this means is that many such symbol elements may not be exactly "to spec" according to the FGDC standard.  This is the reason that some queries are too "fat" for the specified gap distance.

 -- The interval specs for some of the line symbol parts are overly complex (in points, to as many as 3, maybe even 4, decimal places)  This is mostly because of the extreme difficulty in getting the hachures in the hachured fault symbols (scarps of various types) to maintain their correct spacing over a long length.

 -- The symbol names are highly cryptic, owing to line-length limitations in Arc 8.  Also, the names contain symbol numbers that match the "Ref. No." in the standard except that they contain "leading zeroes" so they'd sort correctly.

 -- There are two versions of queried ornamented line types such as thrust faults -- one ending in "quest_dn" in which the queries are right-side-up and the ornament points down, and one ending in "quest_up" in which the queries are still right-side-up but the ornament points up.  This is to ensure that the queries will be right-side-up on lines that curve around in the reverse direction.

 -- There are no accommodations built in to the style for placing line decorations such ball and bar symbols, anticline arrows, etc. -- the style only contains the lines, not the decorations ...

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