An Attempt to Observe Paths of Particle of Wind Flowing over Buildings Utilizing Simplified Aerial Photogrammetry
Toshio Koizumi, Hiroto Hagura
Chiba Institute of Technology
2-17-1 Tsudanuma, Narashino-shi Chiba, Japan
Introudction
It is important in the study of wind to three-dimensionally determine on site the flow of wind near the ground surface.
The authers developed a system to measure the data of wind flow in both the horizontal and vertical directions utilizing aerial photographs.
This system uses two cigar-shaped kite balloons to which is mounted a 35 mm still camera, which stereophotographs a third balloon release as a tracer, thereby three-dimensionally analyzing the third balloon's path of particle.
This time, we utilized a system in observing the paths of particle of wind flowing over a building, and confirmed the effectiveness of the system.
Observation System
This system was developed for the purpose of observing paths of particle of wind flowing.
Fig. 1 shows outline of this system.
Fig 2. Devices and Analysing System for Aerial Photogrammetry Utilizing kite Balloon
This system I composed of following elements as shown in Fig. 2.
1) A kite balloon born camera system.
- Balloon ; 7 m3 , 4.25m3 , helium gus
- String ; 1,000 meter
- Still camera ; 35mm, wide angle, f=28mm (Olympus 0M-1, Canon T70)
- Monitor camera ; Pentax PC-K1200, Sony CCD camera
- Radio control ; Sutter, monitor and angle control Horizontal 360 degree
Vertical ± 90 degree
- Time lag of two camera shutters is less than 0.04 seconds.
- Total payload ; 5.0 kg, 3.0 kg.
2) Analytical system
- Coordinate digitizer ; Resolution 0.025 mm ( Mutoh BL )
- Personal computer ; NEC 9801VX
Fig. 3. shows the signal sending and receiving systems.
Observation of paths of particle of wind flowing over buildings.
The observations were made with buildings in campus of Chiba Institute of Technology.
Fig. 4 shows the site of experiment.
Fig. 5 shows drift route of balloon.
Fig. 6 shows release of balloon.
