Notes on Manmade data, SDTS format

The manmade data do not convert very smoothly to a shapefile via DLG format. The match between line or arc files converted this way and converted in Arc/Info, and then comparing both to the original DLG files, is good.  The polygon data converts well in ArcInfo.   There has been very limited success, however, in converting the manmade polygon data directly into shapefiles.

Even using the SDTSLDLG, running DLGBLD on the manmade data files still does not work consistently.  It ceases to function when it encounters area data in the DLG file.  Despite this fact, once the rest of the programs are run and the data converted to a shape file, the point data appears to be accurate.  The polygon dat file, however, would not open. 

The feature attribute primary module for manmade data contains the letters AMSF in the name. In some cases there may be a coincident attribute primary module with the letters ACOI in the name. This coincidence module is fairly common in the manmade data.

The SDTS2DLG program creates a DLG and a DLA file when run. Running the DLGBLD program links the records within the DLG file. The DLA file contains information about the topology of the data (line, node, etc) and functions as a link between the attribute information and the actual topology features. The first column indicates Area, Point, Line or Node. The second links to a record id in the attribute file (RCID), while the next column links to an attribute id in the attribute file (ATID and RCID). The fourth column matches the minor code in the DLG file, and the last points to the file where the attribute will be found (most often the feature attribute primary module).  Since the BLGBLD program does not always complete, it is very difficult to actually relate the polygon attributes,

The following is sample data from the manmade DLA file.

A, 2082, 2082, 2081 , PC01
A, 2083, 2083, 2082 , PC01
A, 2084, 2084, 2083 , PC01
P, 1, 1970, 2084 , AMSF
P, 2, 1971, 2085 , AMSF
P, 3, 1972, 2086 , AMSF
L, 2493, 4442, 4556 , AMSF
L, 2496, 4443, 4557 , AMSF
L, 2642, 4444, 4558 , AMSF

The PCATDUMP program creates an equivalent format file for the polygon data; I have used the naming convention of putting pol.dat at the end of the file that is created in my documentation although the program does not require a specific name.  The Avenue script that converts this file to a DBF file does require that naming convention. (again, this is inconsistent)

The ATTR2DAT program creates a file from the feature primary attribute module. This file contains attribute information in a useable format. There is quite a bit of information in the manmade DAT files with unclear purposes. The file is basically an ASCII delimited text file, although it is created with a DAT extension. For the hydrology line data, all except the first two columns were deleted, with no apparent problem with the data.

The following is sample data from the manmade DAT file, directly after conversion:

1,2000150, , , , , , , , , , ,-9, ,-999,-99,
2,2000453, , , , , , , , , , ,-9, ,-999,-99,
3,2000150, , , , , , , , , , ,-9, ,-999,-99,
4,2000420, , , , , , , , , , ,-9, ,-999,-99,
5,2000453, , , , , , , , , , ,-9, ,-999,-99,
6,2000150, , , , , , , , , , ,-9,Y,-999,-99,
7,2000150, , , , , , , , , , ,-9, ,-999,-99,
8,2000101, , , , , , , , , , ,-9, ,-999,-99,
9,2000105, , , , , , , , , , ,-9, ,-999,-99,

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Keywords=GIS, data, SDTS, manmade
Last Modified January 04, 2001 07:46 AM