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As a solution for this problem, it has been desired to grasp the
actual state of narrow roads and generate the maps with high
positional accuracy to improve the efficiency in the
construction control and road administration. Some
administrative agencies are considering preparing the highly
detailed and accurate orthophoto as a part of fundamental data.
Figure 2 shows the image of utilization of basic data to the
construction control at the area of narrow road.
Base map
|
|
|
Overlay analysis, and
Control construction ^£ EE
A record of narrow
Usa
Qc
Present situation
on True ortho photo
Figure 2: Image of using fundamental data for the construction
control at the narrow road areas
The following maters can be pointed out as the technical
problem in this case.
]. There are quite many occlusions of buildings as there
are many tall buildings.
2. [ts necessary to prepare 3 dimensional high precision
building edge line for generating true orthophoto.
3. Shaded portion is larger at the building crowded area,
and therefore, it is difficult to take a clear aerial
photography.
4. It is difficult to spend high cost comparing with the
cost necessary for the generation of ordinary orthophoto.
Based on the recognition of these problems, we discussed the
generation method of true orthophoto applying and taking
advantage of merits of area sensor type digital aerial camera
DMC.
3. DISUCUSSION OF METHOD
3.1 General description of area sensor type digital aerial
camera DMC
DMC is an area sensor type aerial camera using CCD array
(Figure 3). The camera body unit is composed of 8 camera
heads, namely 4 high resolution panchromatic cameras using
CCD array of 7K x 4K and 4 multi spectra cameras using CCD
array of 3K x 2K (Figure 4). The multi spectra cameras collect
data from red, green, blue and near infrared bands. 4 high
resolution panchromatic images are mosaiced by post
processing. Also, RGB or near infrared color image is
synthesized by pan-sharpen processing. Main capacities are
shown in Table I.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004
Figure 4. 8 camera heads
Structure High resolution panchromatic or
multi spectra of 14K x 8K
74 (perpendicular to flying
direction) x 44 (flying direction)
Shooting angle
PAN: 13,824 x 7,680 pixels (final
Resolution, optical system | output image)
4 pieces, f - 120 mm / 1:40
MS: RGB / NIR
Channel, raw resolution, | 3,000 x 2,000 pixels
resolution of pan-sharp, | 13,824 x 7680 pixels (final
optical system output image)
4 pieces; f - 25 mm / 1:4.0
Shutter, Iris Variable 1/50 — 1/300, f/4 — f/22
MDR 840 GB (about 2,000 or more
(Mission data recorder) images)
Shortest shutter interval 2 seconds / image
Radiometry 12bits
Position and Orientation | POS/AV 510
recorder
Table 1. Details of main capacity of DMC
3.2 Proposal method
Using DMC system, we propose the method of generating
true orthophoto for suitable application purpose and cost
effectiveness under conditions listed below.
e Taking high-overlapped photography without extra
cost.
e Acquisition cost effective 3 dimensional vector data
