Ebrahjm, Mostafa Abdel-Bary 
  
In Islamic cultures the so-called decorative arts provide the primary means of artistic expression, in contrast to Western 
art, in which painting and sculpture are preeminent. Illuminated manuscripts, woven textiles and carpets, inlaid 
metalwork, blown glass, glazed ceramics, and carved wood and stone all absorbed the creative energies of artists, 
becoming highly developed art forms. These works include small-scale objects of daily use, such as delicate glass 
beakers, as well as more monumental architectural decoration, for example, glazed tile panels from building façades. 
Such objects were meticulously fabricated and carefully embellished, often with rare and costly materials, suggesting 
that the people for whom they were made sought to surround themselves with beauty. (Linda Komaroff, 1999) 
Decoration is a major unifying factor in Islamic architecture and design. Decoration has linked buildings and objects 
from all over the Islamic world - from Spain to China to Indonesia. Islamic art is an art not so much of form as of 
decorative themes that occur both in architecture and in the applied arts, independently of material, scale and technique. 
There is never one type of decoration for one type of building or object; on the contrary, there are decorative principles 
that are pan-Islamic and applicable to all types of buildings and objects at all time. (Islamic Arts and Architecture 
Organization (a), 1998) 
The effect of the Islamic decoration is extraordinary and its function quite unmistakable. The Islamic decoration goes 
hand in hand with the non-directional plan, the tendency to an infinite repetition of individual units(bays, arches, 
columns, passages, courtyard, doorways, cupolas) and the continues merging of spaces without any specific direction or 
any specific center or focus. And if a definite spatial limit is reached, such as a terminal wall, the surface that should 
stop the progress of anyone moving through the building will be decorated with patterns that repeat themselves, leading 
on visually beyond the given limit of the wall, surface, vault or dome. (Islamic Arts and Architecture Organization (b), 
1998) 
1.2 The Accuracy 
The accuracy is an important element in the world of measurements. So, it has been defined in several text books and 
articles. As example, Edward M and Gordon Gracie, 1981 defined the accuracy as the degree of conformity or closeness 
of a measurement to the true value. They state that accuracy includes not only the effects of random errors but also any 
bias due to uncorrected systematic errors. If there is no bias, the standard deviation can be used as a measure of 
accuracy. 
Buckner R.B., 1983 defined accuracy as the degree of conformity with a standard (“the truth”). He mentioned that the 
accuracy relates to the quality of a result, and is distinguished from precision, which relates to the quality of the 
operation by which the result is obtained. 
Kenneth E. and Donald J., 1995 defined the accuracy as the degree to which information on a map or in a digital 
database matches true or accepted values. Accuracy is an issue pertaining to the quality of data and number of errors 
contained in a dataset or map. 
Buckner R.B., 2000 wrote that the accuracy has only one meaning: conformity with the truth. The truth in measurement 
science is defined by one or more of the following: 
* An adopted physical or other standard (on distance, weight, volume, time, etc.). 
* Geometric laws. 
* A system decided as correct by some recognized authority. 
In theory of errors of measurements the term accuracy is traditionally used for a concept that measures the closeness of 
derived estimated or predicated data to reality. (Ebrahim, 1992) 
The accuracy can be evaluated by using one of the following two methods (Hottier, 1976 ) : 
1- Check measurements 
2- The accuracy predictor 
In the first method, the photogrammetric results are compared with the results obtained from a more accurate measuring 
procedure. The accuracy predictor is a theoretical way to evaluate a system using its main parameters. 
Fraser,1990 agree with Hottier, 1976 for the first method and mentioned that “If check points are available in the object 
space, the root-mean square (RMS) errors of photogrammetrically determined target point co-ordinates can be used as 
an accuracy measure”. 
  
196 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 
  
  
  
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