For close-up photogrammetry, it is recommended that the user manually set the camera to focus to the calibrated infinity, the camera is in M mode, set the appropriate shutter and aperture, turn on the AutoISO option, and the metering mode is global metering.
When the light conditions are better and the fineness requirements for the collected data are higher (the smaller the GSD), the distance to the photographed object will be closer.
At this time, you should select a small aperture (Fno large) to ensure a small hyperfocal distance and keep the object being photographed in a clear state.
When the highest clear resolution corresponding to a large aperture meets user needs, try to select a large aperture to obtain greater luminous flux.
In environments with better lighting conditions, you can choose a faster shutter speed to avoid motion blur.
Recommended to use the aperture between f/5.6-f/11. The planning of the close-up photogrammetry route can be completed using the M300 waypoint flight function. The specific preparation steps and operation steps are described below.
close-up equipment required for image measurement
DJIP1*1
M300 aircraft*1,
M300 remote control*1.
Planning steps
(1) Determine the distance between the route plane and the captured facade
If the takeoff point can be placed within a few meters from the captured facade, the takeoff point can be placed near the captured facade, and the aircraft can be flew away from the captured facade. By checking the distance between the aircraft from the Home point on the APP, the distance between the route plane and the captured facade is approximately estimated. Please pay attention to avoid obstacles above the aircraft during takeoff.
(2) Manually plan
A. Manually fly the aircraft to the distance required from the photographed facade, adjust the altitude and position so that the aircraft is at the first waypoint of the facade route. The aircraft hoveres, return to the homepage of the APP, click Route Flight-Create Route-Let’s Flight-Select Points to enter the waypoint flight planning interface: Zoom in the map to the maximum level, and manually add a starting waypoint at the position of the aircraft:
B. Manually control the second waypoint from the aircraft to the bottom of the facade route. After the position is determined, add the second waypoint manually at the position of the aircraft at this time, and then save the route. In order to save power, it is recommended to save the route and lower the aircraft back to the takeoff point.
C. After the aircraft lands, select the route task that has just been saved, click Edit route - Manually edit, and manually add the remaining waypoints. Note that according to the planning method of the zigzag route, you can improve operational efficiency. The third point needs to be planned directly above the second point, the fourth point is planned directly above the first point, the fifth point needs to be planned directly above the fourth point, and so on.
* Example: The relevant route parameters of the route in the facade model are as follows:
.76cmGSD,
5mm Lens: The distance between the route and the wall is 60m
side overlap rate: 70%
Heading overlap rate: 80%
Heading overlap rate: 80%
0 Timed photo interval: 1s
Aircraft horizontal flight speed: 8.3m/s
Camera shutter speed: 1/500
Aircraft vertical route interval: 11m
*Flight speed and vertical route interval calculation method:
Create a new aerial mission to build a picture. Select the corresponding model of P1, and set the flight altitude to the opposite side.
A. The heading overlap rate is set to the desired heading overlap degree. The maximum flight speed that can be achieved at this time is the flight speed of the facade route.
B. Set the heading overlap to the desired side overlap. The maximum flight speed value *1* (2/3) that can be achieved is the longitudinal route interval. Among them, 2/3 of the photos are the ratio and 1 is the timed photo interval.
Method 2 (Acceleration and deceleration optimization is not considered, not recommended):
calculates the moving distance in GSD.
Flight speed = 8192*(1-heading overlap rate)*GSD/100; longitudinal interval = 5460*(1-sided overlap rate)*GSD/100.
(3)
After manually setting the points, the parameters of the route and each waypoint are set. The route parameters and some waypoint parameters are shown in the figure below (the height of each waypoint can be calculated based on the schematic diagram of the route results at the end of the article and the route interval. For example, set the height of waypoints 1 and 2 to 25 meters, then the height of waypoints 3 and 4 is 36 meters, and the waypoints 5 and 6 wayspoints. The height is 47 meters, and the height of the remaining waypoint is derived from this type. )
(4)
set the waypoint action of waypoint 1 as: start taking pictures at the time interval; the action of the last waypoint action: ending the time interval, no action is required for other waypoints.
(5)
After the route and waypoint parameters are set, save the route.
(6)
Infinity focus (important): Manually control the aircraft to fly to an altitude above 60m, and it is recommended to fly to an altitude of 80 meters.
camera is set to -90 degrees, the focus mode is set to AF, click the center of the screen to focus, and after the focus is completed, the focus mode is cut to MF, which is equivalent to saving the infinite focus parameters.
Follow up until the task is over. Do not touch the screen for secondary focus.
(7)
After the focus is completed, lower the altitude of the aircraft and fly manually to the near the first waypoint near the first waypoint. Call the waypoint flight mission saved in step (6). After the aircraft reaches the first waypoint, the mission will be performed in the direction of the route. At this time, manually control the YAW axis and the gimbal pitch of the aircraft as soon as possible to aim the camera lens at the camera facade. The route mission can be automatically carried out without other operations.
(8)
After the mission is completed, the aircraft will be controlled to land safely.
route result example
DJI P1 30 meters close photography modeling results display:
camera focus mode
The above case, the S-speed used in the camera mode, that is, the shutter priority gear, and the shutter speed of the camera is fixed.
In fact, in close photography modeling, you can also use A-level, that is, aperture priority mode, to lock the aperture value to achieve infinite focus at a shorter distance.
Recommended parameters are as follows:
mmGSD,
5mm Lens: 30m
side overlap rate: 70%
Heading overlap rate: 80%
Heading overlap rate: 80%
Timed photo interval: 1s
Calculate
horizontal flight speed: 4m/s
vertical route interval: 4m
Camera A: 5.6 aperture
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