8)
se
ve
+1,
the
0)
1)
2)
1 Or
13)
Aluir Dal Poz
e Dy. isthe predicted residual of b or b* and is the second element of v;
e Sa" \s the standard deviation of n... and is the square root of the first element of diagonal of c;
® Spy is the standard deviation of nn, ,. and is the square root of the second element of diagonal of c; and
e — Wy,. and. Wy are the normalized corrections.
The observations a (or a*) and b (or b*) do not have errors when the values w,,« and Wins, With the significance level a ,
are contained in the intervals:
-Na p < Wa «Nan» and -Na D € Ww «Na n (14)
where, Na / is extracted from normal curve.
3 RESULTS WITH REAL DATA
The entire system has been implemented in C language, with a command line user interface and it has been designed to
be automatic. All the routines including estimation and image processing were in-house developed.
3 : F ka ; Ri "
A EN M 3 n S R
i. lui Od ig
Figure 4. Results from the pipeline for feature extraction and matching
(a) Window automatically extracted from the original image (grouping 3 — highlighted in
table 1);
(b) Edges obtained by applying the Nevatia and Babu filters and automatic thresholding;
(c) Thinned edges with non maxima suppression and filtering of isolated elements;
(d) Straight lines after line fitting. The highlighted lines (1) and (2) were previously
known in the object-space and the line (2) was correctly matched.
Experiments with real data were performed in order to verify the potential of the proposed method. A scanned aerial
photograph (1:8.000) of Rio de Janeiro City was used. The original image was resampled to a pixel size of 75m in order to
facilitate the debugging of the C codes and to avoid a large data set. Experiments with the original data are being conducted
and will not be reported in this paper.
Selected Number of straight lines
Groupings Object-space Image-space
l 4 6
2 6 10
3 2 6
4 2 9
5 2 4
6 2 10
Table 1. Image and object-space groupings
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000. 211