comparison of repeated measure 
quality of che production proc 
ii 
D. Ei 
Un 
ents and relates to:the 
S 
d 
( 
Positional Accuracy 
  
Positional accuracy of'a DIM is a measure of all errors 
with respect to a fixed (absolute) or relative (local) 
coordinate system. Such errors include horizontal-and 
vertical displacement, rotation of axes, and non-linear 
differential scalin ng/warpage in any direction. Systematic 
errors can be described by a seven parameter non-linear 
error function: 
E (X, Y, Z, gy $, K, Sis 
where; X, Y Z are translational errors: 
wy 0, x are rotational errors; 
S'is.the.non-Iáinear scaling-error. 
It is not always a simple matter to determine for a single 
point in a DTM which of the seven parameters is contribut- 
ing to a positional error, but there may be global solutions 
for the entire DTM. 
Data Commonality 
  
Data commonality is the degree of congruence between dif- 
ferent DTIM's; i.e., the degreeiito which two DTM's have the 
same parameter values for the same geographical location. 
Data Compatibility 
  
Data compatibility is the degree of agreement between dif- 
ferent DIM'ss i.e., the degree to io ch two DTM's have 
parameter values within the preci RE of each 
other for the same geosraphical n 
Compression 
io 
(Representation) Error 
  
Once DIM information is compiled, further proce 
add additional errors into the DTM when it is c 
Or reformatted. A varietv of compression algori 
been developed. Additionaliv, various structur 
formations have been used for user specific requirements. 
Jancaitis (1977) developed a RerRedotos y for the *rans- 
formation of uniformally gridded dig tal elevation values 
into coefficients for polynomial su ce patches, Jacobi 
and Kubik (1682) and SRE erai. User address 
the problem of usins'fractals to de 
resea 1 
ov om C. T 2 x 3 ec T7 1 , 
ness. oeverai A rChers have inv