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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
The Quality control result is described in Evaluation Report and 
possible result can be that product is accepted or rejected. Final 
product should be after corrections accepted and officially 
approved. 
6. ORTHOPHOTO QUALITY ELEMENTS 
After spatial data production and delivery finished the process 
of Quality Control in Croatian Geodetic Institute can start 
according to implemented rules. 
Orthophoto production is described in Specification (SGA, 
2004) as well as final delivered product. Specification consists 
of guidelines for delivery orthophoto product and 
documentation from the process of production. From 
Specification clearly come out Quality elements and 
subelements (CGI, 2004a) that are subject of Quality control. 
The list of Quality Elements (QE) contains: Overview, Spatial 
Characteristics, Completeness, Logical Consistency and 
Positional Accuracy. 
All QE are further divided into subelements: 
Overview 
o Configuration 
o History 
o HW an SW Description and Production 
report 
Spatial Characteristics 
o Orthophoto Characteristics 
o Frame characteristics 
o Mission Metrix (location) 
Completeness 
o Commission 
o Omission (missing photos or toponyms and 
road names) 
o Completeness of Toponyms and Road 
Names 
Logical Consistency 
o Format Consistency (files can be opened 
and viewed, file names and formats, 
correctness) 
Positional Accuracy 
o Absolute Accuracy 
Using appropriate software and prepared spreadsheets in excel 
format controller is performing quality control. 
The main condition for further controls is passed control of 
delivery. There is no sampling method used for this control. 
The criteria are that corrupt or missing deliverables is not 
acceptable. In this process should be checked received material 
against the delivery list, present all deliverables in delivery and 
check that all data files are readable. The principle is if this first 
control not passed the product and whole delivery should be 
rejected before next detailed controls. If delivery passed on 
control further controls can be perform. Because of system of 
predecessors controller should check if results of previous QC 
of predecessor products passed on control (Scanned photo, 
Aerial Triangulation and DTM). In Production report should be 
inspect description of used software and hardware to finish 
control of overview quality element. Control of subelement 
Orthophoto characteristics contains check geometric resolution, 
radiometric resolution and distribution of histogram. For gray 
scale orthophotos distribution of histogram shall be 
approximately between 5 (black) and 250 (white). The values 0- 
5 and 250-255 are not allowed. Similar situation is also with 
RGB colour orthophotos and distribution of each channel (red, 
green and blue). Check of location (origin, dimensions and 
resolution - Figure 6) each orthophoto should passed 100 %. 
Appropriate method for that control is fully automated. 
Origin 
Dimensions 
X: 16448250.0000 
Width: 12250.0000 
Y: 15067000.0000 
2: 1 0.0000 
Height: j 3000.0000 
Pixel Size ^| 
Number of Pixels 
X: 4500 
Y: 6000 
X: 10.5000 ~2i 
Y: [05000 _j 
Figure 4. Control of origin, dimensions and resolution of 
orthophoto image 
According to Contract for production data full area should be 
covered with orthophotos (excess and missing are not allowed). 
Inspection of Toponyms and Road Numbers (Figure 5) as 
cartographic part of orthophoto product (see Figure) check 
according to official sources like Croatian Base Map in scale 
1:5000 (check of toponyms) and classification of public roads 
(road numbers). 
Figure 6. Toponyms and Road Numbers on Orthophoto 
Positional accuracy and their sublement absolute accuracy 
control by field control method. Objects in the field are 
measured using GPS, and this true position (e.g. road 
boundaries) is used to control the accuracy of the Orthophoto 
(Figure 7).