Estimating Map Document Quality
To define and specify map output accuracy, certain assumed
standards will be made to simplify the discussion.
e A uniform line of 8 mils is used as the standard line
width for compiling maps. Then line compiling skill
causes a random error in 8 mil lines of about +4 mils
(0.1mm) standard deviation.
® The planimetric deviation in the manuscript due to
the accumulated errors in the total aerial photo-
grammetric process is estimated to have a standard
deviation held to *4 mils (0.1mm) when compiled at four
times the aerial photo scale. The accumulated error
sources include those of the atmosphere, camera, film,
data processing, printer, diapositive, and stereoprojection
) through lenses or mechanical linkages.
9 The eight-mil mylar documents averaging 30- by 20-inches
are used for drafting and later printing and processing
of separation negatives. With minimum stretching from
normal productive handling these documents can be held
to a random accumulated error of +4 mils.
9 To convert line maps by a precision scanner and sub-
sequent digital processing, it is estimated that 4-mil
steps (or unit vectors) are sufficient to digitize a
line and to detect the line center. The 4-mil steps
are to be maintained at the -*l1-mil precision of the
Scanner, resulting in the fourth source of a +4 mil error.