3.2 The theoretical accuracy of large spatial blocks with independent models 
b .2.] Extent of the investigation 
In this extensive study Mr. SCHUHMACHER investigated five different square shaped blocks with 5, 
10, 15, 20 and 25 strips each. All the blocks treated were schematiced: 60 9, forward overlap, 8 tie 
points per model in idealized position including the two perspective centers, flat terrain. The plani- 
metric as well as the height control was changed and both 20 9, and 60 %, sidelap were investigated. 
In addition different accuracy assumptions were made for the control. 
On the whole Mr. SCHUHMACHER performed 90 block runs. Therefore 25 system hours were needed 
on our fast Control Data computer CDC 6600. The largest block investigated contained 1640 indepen- 
dent models. 
The study gives a lot of valuable information and will be published separately by Mr. Scuun- 
MACHER in a photogrammetric journal. Here only the most important results can be presented in a 
comprehended form. 
3.2.2 Results for 20% and 60% side lap, wide angle photography and errorfree control 
The planimetric accuracy was found as practically independent of the height control distribution 
and analogous the planimetric control has nearly no influence to the height accuracy. So the results 
for planimetry and height can be considered independently. 
In planimetry 4 different perimeter control distributions were investigated: 
P1. dense perimeter control, distance 2 base lengths 
P2. 16 regular distributed perimeter control points 
P3. 8 control points positioned in the block corners and in the centers of the block edges 
P4. 4 control points positioned in the block corners 
Figures 1 and 2 show the planimetric results for 20% sidelap and for 60% sidelap, respectively. 
In both figures the standard deviations ox mean and oy mean of the planimetric coordinates x and 
y of 9 - 9 — 81 adjusted minor control points distributed in a regular screen over the block are 
plotted against the number ns of strips in the block. ox mean and oy mean are given in um refered 
to the image scale as well as in units of the standard deviations ox = oy of the planimetric coordinates 
of the model points (table 1). 
> © Gmean 
[um] t s of6x= Sy P1,P2,P3,P4 control variants 
    
   
  
  
L e 
50] ^0 €. 9x mean PA 
O 
-60 o Sy mean 
40+ —— approximating curves 
5,0 
30740 
4 
r30 
207 
‘ F20 P3 
107 : ES P2 
1,0 P1 
5 10 15 20 25 strips 
Fig. 1: 0x mean, Oy mean for 20% sidelap, wideangle photographie and errorfree control