—————
in both direc.
features have
also the basis
), but most of
ch do not con-
^tter condition
rplane (Aveni,
balloon or too
aerial images
imber of
trol points
(signal.)
0
(signal.)
0
(natural)
all the excavæ
use of lack of
Plotters AC
Beutner, Sabine
and S9. The triangulation of the Palpa color block was performed with 88 images and 8 control points. Since we were
not very happy with the quality of the color images we ordered a B/W photoflight to be done one year later. At that time,
without us being in the area, the signalized ground control points were not available any more. Also, kinematic GPS was
not used. Therefore we had to measure the B/W block without any control points and connect it via joint tie points to
some images of the color block. We did a joint bundle adjustment of both the color and B/W images including kinematic
GPS data (BW+C). Table 2 gives the results of triangulation.
Version number of images number of control points kinematic GPS oo [Um]
B/W+C 211 8 yes 13.3
Table 2: Triangulation characteristics for Palpa
Although the photoflight was meant to produce an image scale of 1:5 000 the actual scale turned out to be 1:7 000. The
overall block accuracy, as indicated by o — 13.3 Hm, corresponding to 9.3 cm on the ground, was good enough for the
purpose at hand. It was clear that at this fairly high noise level self-calibration would not help improving the results and
was therefore not used.
3.2 DTM Generation
In order to generate a DTM of the Palpa area a total of 57 B/W stereo pairs had to be measured. We decided to go with
manual measurements because we needed a very precise DTM, especially for the integration of the image texture map
and vector data of the geoglyphs. Any deviation between vector data and texture would have been noticeable very easily.
Our previous experiences with automated commercial image matchers convinced us that these could not give us the
required performance.
We used profile measurements at a profile distance of 20 m with additional breaklines. This gave us about 200 000 points
for an area of about 2 km by 9 km. Later on we also integrated all the extracted geoglyphs as breaklines into the DTM.
Figure 4 shows the shaded version of a wireframe model of the DTM with the plateau Cresta de Sacramento as the major
site of geoglyphs. The flat region is the Rio Grande valley. The major excavation sites La Muña and Los Molinos are
indicated.
Los Molinos
La Muña
*Fig.7: Geoglyphs
Fig.8: 3-D model
Cresta de Sacramento
Figure 4: Shaded DTM of the Palpa area
The wireframe model serves as the basis for orthoimage production and visualization. We have produced wireframe
models at various resolutions according to the different purposes. Rasterwidths range from 25 m for overview representa-
tions down to 1 m for highresolution applications.
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 57