DIGITALNA ARHIVA ŠUMARSKOG LISTA
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|ŠUMARSKI LIST 7-8/2021 str. 73 <-- 73 --> PDF|
Vertical Accuracy – Vertikalna točnost
The comparison of the results of the PPK and static surveys for P5, P6, P7 and P8 points show that the variations were generally about ± (8-272) cm in vertical coordinates between 10:00 hour and 15:30 hour, see Figure 8 (except for 11:30-11:45 hours). The ambiguity solution not fixed at this time period. Between 11:30 hour and 11:45 hours, the integer ambiguity value fixed. The vertical coordinate differences at this period between the PPK surveys and the static surveys differed up to about ±20 cm, see Figure 9.
The comparison of the results of the PPK and static surveys for P5 point shows that the variations were generally about ± (1-10) cm in three dimensional coordinates between 10:30 hour and 15:30 hour, see Figure 10. The comparison of the results of the PPK and static surveys for P6, P7 and P8 points shows that the variations were generally about ± (0-1000) cm in three dimensional coordinates between 10:30 hour and 15:30 hour. The signal scattering due to the trees causes strongly fluctuating epoch results for three points, with ranges of ± (0-1000) cm for the north, east and height components, see Figure 10. The impact of the bad signal quality on the positioning results is naturally worse for kinematic positioning than for static processing occurs.
The coordinate differences at the certain time intervals for P6, P7 and P8 points in the forest areas between the PPK surveys and the static surveys differed up to about ± (0-50) cm, see Figure 11.
Consistency of the Static and PPK Results – Dosljednost statičkih i PPK rezultata
To check the compatibility of the PPK technique with the static technique, the three dimensional (3D) misclosure vectors were computed as follows (Pirti 2013):
m2p = (XPPK – XStatic)2 + (YPPK – YStatic)2 + (HPPK – HStatic)2 (1)
mP is the misclosure vector (in metres) for all of the points, YPPK and XPPK are the easting (Y) and northing (X) coordinates (in metres) of the four points from PPK survey coordinates, YStatic and XStatic are the easting and northing coordinates of the four points (P5, P6, P7 and P8) from static surveys.
Figure 12 shows the horizontal misclose vectors for these four points. In this study the most important criteria in PPK measurement technique are survey time and fixed of the integer ambiguity value. Except for the partial and float ambiguity solutions for P5, P6, P7 and P8 points within forest and unobstructed environments (see Figure 12), the results clearly show that the PPK technique is a stable method and about ± (0-100) cm level of accuracy is generally obtainable (Pirti 2009).