The Intet national Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
4.2. Determination of the solar radiation 
The solar radiation is determined from the solar radiation 
database. Solar radiation is determined in MJ/m 2 /year. It 
depends on the location of the object in the particular radiation 
zone. Medium values for those 4 zones are varying from 3700 
to 4500 MJ. 
Figure 6. Solar determination radiation regions (alpine, dinaric 
mountain, panonian basin and Mediterranean region), 
4.3. Area of the object 
In case of the parcel, the area is determined directly from land 
cadastre. If the object is building the area of the roof is 
determined directly from cadastre of buildings or by counting 
the pixels (0,5m x 0,5m) in digital orthophoto. In both cases the 
area has to be corrected by the inclination factor. 
| Parcefs 2403.shp 
□ 
Plan shp 
□ 
| Sis vàe. shp 
[=□ 
Dkn.shp 
□ 
G25«?062c.tif 
Segment Length: 9.68 m Perimeter: 72.36 m Area: 254.69 sq m 
Figure 7. Area determination 
4.3. Azimuth 
Azimuth determination for parcels is determined by digital 
slopes orientation database. 
Figure 8. Azimuth determination for parcel 
The azimuth of the roof can be determined through computation 
based on the measured coordinates of the relevant points on the 
roof. Due to simplicity the azimuth in the operational 
photovoltaic system is defined just by overlaying a compass 
based diagram on the displayed object. The reading is recorded 
manually. 
Figure 9. Azimuth determination for object 
4.4. Inclination 
Inclination of the roof is determined by using formula 
b 
tga = - 
a 
where b = roof height obtained from the cadastre of buildings 
a = horizontal component of a steep, measured from 
DOF 
55