INCREASED IMAGE QUALITY RESULTING FROM NEW TECHNOLOGIES IN AERIAL CAMERAS
Dipl.-Ing. Roland Schlienger
Co-authors: Peter Fricker, Arthur Rohrbach, Holger Schade
Leica AG, Aerial Visionics Systems
CH-9435 Heerbrugg, Switzerland
Presented paper for the XVIII Congress ISPRS Vienna, 1996, Commission I, Working Group 1
KEY WORDS: Camera, Aerial, Resolution, Distortion, Performance, Large, Small, Scale.
ABSTRACT:
A link in terms of image resolution is developed between new optics for the Leica RC30 Aerial Camera with forward image motion
compensating device and the new PAV30 Gyro-stabilized camera mount. Moreover the progress in reduction of distortion and
improvement of resolution of the Wild / Leica lens cones f = 153 mm and f= 303 mm in the last three decades is shown.
Theoretical evaluations illustrate the improvements through compensation of forward motion and angular camera rotations, essentially
for large-scale photography.
The parameters qualifying image resolution and geometric accuracy in mapping are given for the new 15/4UAG-S and 30/4NAT-S
lenses with laboratory measurements: modulation transfer function (MTF), resolution for high and low contrast targets, homogeneity of
spectral transmission and distortion.
Geometric accuracy is illustrated by results of test flights performed by Leica with very large image scale (1:2 500, flying height 380 m
and 760 m). Even for longest exposure times (1/100 s) and intentionally disturbed aircraft stability in pitch, roll and yaw, the small
residuals on control points (East and North + 1.5 cm, height + 3 cm) confirm the theoretical expectations. The dramatic improvement of
system quality is obtained at full aperture f:4.
RÉSUMÉ:
Il est développé le lien en qualité d'image entre la résolution de nouveaux objectifs pour chambre aérienne Leica RC30 avec
compensation du filé d'image et nouvelle suspension gyro-stabilisée PAV30. Une rétrospective illustre le progrés en réduction de
distorsion et accroissement de résolution des objectifs Wild / Leica f= 153 mm et f= 303 mm durant les trois dernières décennies.
Une évaluation théorique montre l’amélioration en résolution par compensation du filé d’image suite par déplacement de l'avion et rota-
tions de la chambre aérienne, en particulier pour les grandes échelles.
Les paramètres déterminant qualité image et géométrie sont quantifiés pour les nouveaux objectifs 15/4 UAG-S et 30/4 NAT-S: transfert
de contraste (MTF), résolution pour mires fort et faible contraste, homogénéité de transmission spectrale, distorsion.
Finalement, la précision géométrique est documentée par des vols à très grande échelle (1:2 500, hauteur de vol 380 m et 760 m)
effectués par Leica. Même avec temps d'obturation maximal (1/100 s) et déstabilisation intentionnelle de l'avion en roulis / tangage /
lacet, les faibles résidus sur les points de contrôle (Est et Nord +1.5 cm, altitude +3 cm) confirment les pronostics théoriques. Un
accroissement considérable de qualité du système est obtenue déjà à pleine ouverture f:4.
INTRODUCTION Weighted Average Resolution‘) in linepairs / mm for the optimal
aperture f:4 or f:5.6 (older lenses max. f:5.6).
In the last decade the increasing demand for both large scale
aerial surveys and economic high-altitude photography with
highest image quality led to extremely stringent specifications
for nearly all links in the quality chain of aerial camera systems.
New technologies used in the Leica RC30 Aerial Camera System
now make it possible to profit from the higher image quality of a
new lens generation.
EVOLUTION OF DISTORTION AND RESOLUTION OF
LEICA AERIAL CAMERAS
Figure 1 illustrates the progress in resolution and distortion of the
standard wide-angle lens cone f=153 mm (6“) and the narrow-
angle f=303 mm (12*). The latter being the lens mostly dedicated
to large-scale photography. The maximum distortion is given for
the maximum lens aperture, the AWAR resolution („Area
176
All values are related to high-contrast targets (contrast 100:1 or
log k = 2) imaged in the image frame of the lens cone by
collimators spaced at 5°. The typical high-resolution film for
high-altitude survey flights Kodak Panatomic-X 2412, also used
for the lens Calibration Certificate, has been taken as a reference.
At £4, the mean AWAR for Panatomic-X at high contrast exceeds
clearly 120 Lp/mm for the new generation lens 15/4UAG-S and
105 Lp/mm for the 30/4NAT-S type. AWAR values of the same
magnitude have also been obtained when calibrating the
15/4UAG-S on the multicollimator of the U.S. Geological Survey
(USGS), which included the use of other test parameters such as
the emulsion type (Spectroscopic V-F) and the size gradation of
the test targets.
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996
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