The second simulation was performed with only 4 full control points in
the corners of the block. The coordinates of the control points were
assumed as error-free.
Finally, in the block adjustment only the given DTM (see figure 7),' i.e.
no control points or any other control information was used.
For this special case of combined point determination two simulations
were performed:
- DTM information is available for all 100 object points
7 DTM information is given for only 7 object points.
In this case the datum of the block is just determined.
The heights of the DTM nodes were assumed as error-free. In the adjust-
ments condition equations were used to keep the object points on the
bilinear surfaces of the concerned DTM meshes,
The following table shows the RMS values u$, u$, us of the Standard
deviations O&is Ojis c2; Of the adjusted object point coordinates Xi;
yi» 2j for all four simulations:
simulated examples m My us
1 : error-free orient. parameters 0.09 m | 0.10 m | 0.30 m
2: 4 error-free full control points | 0.20 ml 0.22 m 0.61 m
3: error-free DTM for all 100 points; 0.19 m| 0.19 m | 0.09 m
4.02 m | 1.21 m
4 : error-free DTM for only 7 points 2.38 m
A comparison of simulation 2 with the theoretical case of simulation 1
illustrates the high stability of the three line imagery block, even
with very sparse control.
Simulations 3 and 4 show that in principle classical control information
can be replaced by an available DTM, The accuracy of the adjusted X, ÿ
and 2 coordinates is dependent on the number of points with DTM infor-
mation, the DTM accuracy and the shape of the terrain.
4. CONCLUSION
Much R&D work still has to be done in connection with the use of opto-
electronic three line cameras. Some future tasks are mentioned briefly:
- the direct use of the pixel numbers aij. Dii, Cjj and read cycle
numbers dj in the observation equations of the least-squares ad-
justment instead of the use of derived image coordinates Xijs Yij
- detailed investigations concerning minimal configurations for
three line imagery
- 220: ~
