001362L 1 0600049   22040000210000012921DQHL37500000;&1107DQHL.DDF0100;&DDF RECORD IDENTIFER1600;&LineageMODN!RCID!COMT(A,I,A)01754 D 1   00043   4104000100080DQHL170380000001DQHL1CONVERSION TO SDTS: This DEM was converted to SDTS Raster Profile as
part ofa mass conversion of US Geological Survey Digital Elevation
model archive to SDTS.  The data organization was changed from a
southwest origin with south to north scans to a northwest origin with
west to east scans.  The x,y grid positions were not altered -- i.e.,
the data was not resampled.  The UTM gridded DEMs are ragged in their
native form.  A fill value was used too make the DEM grid rectangular
in this transfer.


GENERAL NOTES: A number of factors affect gridding processes and the
accuracy of the final DEM product: 1) A dependency exists between the
scale of the source materials and the level of detail or grid
refinement that is possible from a given source.  2) During the
process of changing scale, from large to small, some source data may
be generalized or dropped out and, therefore, some features would not
be available for formation of, or incorporation into, a grid at that
scale.  3) The process of forming a grid with regular spacing requires
the transfer of precise point or vector data to generalized grid
square corners using a process similar to taking a simple weighted
average.  This process may alter the apparent position upon display of
point or vector source data, reducing the ability to recover positions
of specific features whose dimensions are less than the internal grid
cell spacing.  For all DEM's, the grid spacing and spatial resolution
results in data intervals that span terrain discontinuities, such as
benches, tops, and drainage.  Some features can be appropriately
captured at a given grid spacing while other, smaller features are
subdued or filtered out altogether.00087 D 1   00039   21040001080DQHL4080000002DQHL2DEM CELL NAME: ALANSON, MI-2400000117 D 1   00039   21040001080DQHL7080000003DQHL3PROCESS CODE 5: DLG/hypsography LINETRACE, LT4X complex linear00070 D 1   00039   21040001080DQHL2380000004DQHL4DEM PRODUCER:  00066 D 1   00039   21040001080DQHL1980000005DQHL5DEM LEVEL-200436 D 1   00041   310400010080DQHL38780000006DQHL6DEM LEVEL 2 means: DEM created from digital line graph (DLG) contours or equivalent, or from any USGS map series up to 1:100,00 scale using stable base contour separate or equivalent.  DEM data derived from hyposgraphic and hydrographic data digitizing, either photogrammetrically or from existing maps, are entered into the Level 2 category after review on a DEM editing system.00105 D 1   00039   21040001080DQHL5880000007DQHL7SOURCE DATE OF PUBLISHED MAP OR PHOTOGRAPHY:  198300094 D 1   00039   21040001080DQHL4780000008DQHL8DATA INSPECTION OR REVISION DATE:  199800145 D 1   00039   21040001080DQHL9880000009DQHL9INSPECTION FLAG: Iindicates all process of part three quality control have been performed.00152 D 1   00041   310400010080DQHL10380000010DQHL10DATA VALIDATION FLAG: Level 2 and 3 DEMs reviewed and edited.  RSME computed from test points.00085 D 1   00039   21040001080DQHL3880000011DQHL11DATA EDITION: 1: USGS default00111 D 1   00039   21040001080DQHL6480000012DQHL12GRID RESOLUTION: 30.000000 METERS X, 30.000000 METERS Y01326 D 1   00043   4104000100080DQHL127580000013DQHL13VISUAL VERIFICATION: Because of practical limitations
inherent in all collection systems, there will always be some artifacts
such as benches, striations, patches, or some other anomaly that
imparts some signature of the collection system in the data set.  Some
of these artifacts, although falling within normal DEM vertical error
tolerances, can coalesce with valid surface features. All DEM's are
viewed and edited so corrective actions can be taken to minimize these
artifacts. For example, 1) Isolated tops are depicted with their
approximate size and shape; 2) Flat trending surfaces are depicted as
generally flat trending without confusing patterns or striations; and,
3) Water bodies are flat, lower than the surrounding terrain, and have
shorelines clearly delineated.  Additional testing is performed using
a DEM Editing System (DES) to aid in the identification of blunders
such as irregularly gridded data, mistagging of tops and depressions,
and spikes.  These blunders are generally identified by displaying the
DEM with the aid of DES options, which include color banding of
elevation gradients, stereoscopic viewing using anaglyphic filters,
and shaded-relief enhancement.  An elevation matrix is analyzed in
suspect areas and corrected as required.