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specific points and map details for which there is to be measured photogram- 
metrically both horizontal position and elevation, and for which similar meas- 
urements were made previously by accurate surveys on the ground, the notes of 
which the contracting authority retains. Further ascertaining is done by com- 
paring the positions and elevations determined by the measurements made photo- 
gramnetrically with those from the Surveys on the ground. The results of this 
procedure reveal whether the work of the map testing agent or unit is either 
sufficiently accurate, or not accurate enough for testing maps, or that defi- 
cieneies exist in some or all of the testing instruments, photographic nega- 
tives and photographic transparencies used, or the basic and/or supplemental 
control furnished. 
Map testing is done photogrammetrically when the preceding procedure 
proves such testing is feasible, or not done until after the ascertained defi- 
ciencies are corrected appropriately, according to responsibility, by the map- 
ping consultant and by the testing consultant. 
The map testing results reported include adequacy of the mapping consult- 
ant's utilization of the aerial photography, ground survey control, and photo- 
grammetric instruments; accuracy in the horizontal of the plotted control and 
planimetric features; accuracy in the vertical of the contours, spot elevations, 
and profile and cross sections, when measured photogrammetrically; completeness 
of photographic identification and delineation on the maps of the topography, 
planimetry, and other details; and systematic errors, if any. The reported 
results are reviewed and the maps judged thereby to be sufficient in complete- 
ness and accuracy are accepted. Also, maps are designated which, before rejec- 
tion or acceptance, must be field inspected for completeness, and survey-tested 
on the ground to determine the accuracy of their contours, planimetric details, 
and profile and cross sections. All maps not accepted on the basis of tests by 
photogrammetric methods are tested by field surveys, as previously outlined. 
Finally, acceptance or rejection of maps is made. 
Correction, revision, and completion of maps 
  
As conditions, effectiveness, and economic cireumstances warrant, the 
correction and/or revision and completion of maps are accomplished by field sur- 
veys, by photogrammetric methods, or by a combination of both of these methods. 
The procedures for correcting and/or revising and completing the maps by 
field surveys begin with the control surveys on the project wherever errors are 
suspected and verification or disproof of those errors are required. Then 
errors that are found are corrected in both the basic and supplemental control. 
Field surveys are employed for correction and revision of the maps where 
the ground is obscured. Field Surveys are also used wherever preferable due 
to time limitations, economic reasons, and areas being small and isolated where 
the corrections, revisions, or completions must be made; and wherever it is 
essential to make simultaneously the corrections or additions to the maps and 
in the basic and/or supplemental control. 
When correction and/or revision of control are done by & combination of 
ground surveys and photogrammetric methods, supplemental control is bridged 
after localization and correction of basic control by field surveys, and wher- 
ever new photographs are taken. Photogrammetric methods of correction and/or 
revision and completion of maps are employed wherever new photographs are 
required because map deficiencies, as determined by accuracy and map complete- 
ness tests, (1) prove the initial photography is inferior in photographic qual- 
ity, contains detrimental image movement, does not properly cover all of the 
area to be mapped, or is of a scale smaller than practicable for accomplishing 
the mapping at an appropriate compilation scale and to required accuracies; or 
(2) indicate that the initial photography is dimensionally defective. Photo- 
grammetric methods are also employed for similar purposes when initial photog- 
raphy is adequate but systematic and/or random errors in the initial control 
are so extensive in scope throughout the survey project that it is uneconomical