46 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
error more than a specified percent of the total volume. This | As m 
allowable error can be related to a R.M.S.E. of the DTM that usua; 
will be used to generate the cross-sections or profiles. If | proi. 
the DTM has been adequately tested, and it meets the specifi- | terre 
cations, the engineer should be free to pursue the project with | The € 
confidence that the terrain data being provided is adequate for 
his needs. Ine i 
which 
The photogrammetrist, who will probably generate the DTM, know- conta 
ing the limitations of his instrumentation, can specify the terra 
kind of aerial photography he will need, specify the quality See F 
and quantity of field control that is necessary, and design T 
procedures that will assure him that the DTM product will meet The 1 
the requirements. Think of the peace of mind that goes with one a 
the product that meets a certain specification. is de 
69 
N HM—— EAST DIMENSION —— DATA POINTS 
P 
P 
| i 4 
ed 
7] 
DTM 
| INTERPOLATED 
| . POINTS 
S 
"A ; 
= 
LL 
= > 3 
= i | RTARTING 
e : t INOORDINATE 
FH 
e . 
© ‘ 
| . 
! . 
—-— DIST a N EU Mn OMAN DT ed SIZE OF 
EAST LL de of Tr ndn we | BLOCK 
: BLOCK 
DIST. ETE ^ Fig 8. 
NORTH 
| Note t 
i | E brough 
ready i 
É v The cl 
Fig 7. Organization of Terrain Däta round ir 
Stored.