The subject of the patent application is a method of remote simultaneous triggering of cameras and recording the position of central projections of photographs.

The state of the art knows devices for remote triggering of cameras. Such methods do not enable simultaneous recording of positional data of central projections of photographs. It is necessary, however, to correlate photographs with such data, e.g. for the purposes of developing maps or carrying out various photogrammetric measurements. In the absence of the data correlated with pictures, aerial photographs taken by unmanned systems are integrated with the data assigned a posteriori on the basis of the data obtained during the flight (geographical coordinates, among others). In this case the data is not integrated with the photographs. This requires the performance of calculations to determine the data for the purpose of their integration with the photographs, and is also burdened with measurement uncertainty. As a result, there is no accurate correlation of the photographs with the positional data of central projections of photographs, which in turn makes the data prone to errors during further processing. Such errors can be introduced, for example, due to lack of accurate map calibration or due to geometric distortions of the processed images.

It is therefore necessary to automatically integrate the positional data of central projections of photographs, whereas both the photographs and the positional data of central projections should be acquired at the same time. To this end, close cooperation between the cameras and the devices that provide the positional data of central projections of photographs (GPS receivers) is required. The method according to the invention solves the problem of correlating simultaneous triggering the camera and recording the data. The application of this method allows the user to obtain data integrated with the photographs. This obviates the need for the elaborate process of correlating photographs with the positional data of their central projections - it is no longer necessary to match the data for each photograph and risk loss of accuracy.

A method of remote simultaneous triggering of cameras and recording the position of central projections of photographs according to the invention is characterised in that the trigger of the cameras is connected to the cameras, each of which has a separate channel, with a GPS module and a control module in such a way that the GPS module provides the trigger with the longitude and latitude, time, course, speed, altitude above sea level, number of satellites in view, milliseconds of the week and the delay between activating the trigger and activating the shutter. The trigger gathers the data about the operation of the system: the index of trigger activations or the index of shutter activations for each camera channel. The trigger is activated by the measurement of the duty cycle of PWM signal fed to the trigger input. When the trigger activates, the photograph is taken and its data is acquired. The data about the photographs is stored in the mass-storage memory connected to the trigger. The index mechanism correlates the photographs and the data. Preferably, the method according to the invention operates in an automatic mode, where the activation of the trigger and data registration occurs if the limit distance value from the last activation is exceeded, or the time since the last activation has lapsed, without any additional control signals required.

The method according to the invention may also operate in a semiautomatic mode, in which an option is available to activate and deactivate a given channel by PWM signal.

Optimally, a trigger in the automatic or semi-automatic mode uses a flash- lamp interface and all the data is recorded at the time of triggering the shutter, and simultaneously the time between the activation of the trigger and of the shutter is recorded.

The method according to the invention can be used to control more than one camera.

Preferably, the distance or interval criterion can be applied independently to each camera.

The advantage of the method according to the invention is the ability to simultaneously trigger cameras and record the position of central projections of photographs. The invention is applicable in aerial photography, in particular in unmanned aircrafts, which makes it possible to develop precise maps, terrain maps and orthophoto maps.

Embodiment of the design is shown in the drawing in which Fig. 1 shows the functional chart of the method of remote simultaneous triggering of cameras and recording the position of central projections of photographs. The method according to the invention in the embodiment according to Fig. 1 makes it possible to correlate aerial photograph with positional data of central projections of the photographs, obtained from a GPS module. Trigger 1 is configurable if connected by USB to a PC via included software. The configuration of the device is stored in non-volatile memory of the device.

In the work mode the trigger 1 is connected to the cameras 2, the GPS module 3 and the control module 4. The trigger 1 cooperates with GPS receivers that support N EA and UBX protocols. The GPS module 3 provides the following data: longitude, latitude, GPS time, course, speed, altitude above sea level, number of satellites in view, GPS, millisecond of the GPS week, delay between activating the trigger and activating the shutter (the trigger is activated first). The following system operation data is also recorded: whether a photograph was taken, channel of the event (each for one camera), trigger activation index for each channel, and shutter activation index for each channel. This data is saved in a text file in the mass-storage connected to the trigger 1. An indexing mechanism correlates the data and the photograph.

The method can be used in 3 modes of triggering the camera 2: in manual mode, automatic mode and semi-automatic mode. In the manual mode the trigger is activated by the measurement of the duty cycle of PWM signal fed to the trigger 1 input.

In the automatic and semi-automatic mode there are 2 criteria of activation of the camera 2 - physical distance (obtained from the GPS) from the last activation of the camera and the time since the last activation of the camera. The activation of the camera trigger and recording of data occurs when both criteria are met, i.e. when the limit is exceeded the limit value of the distance from the last activation or the limit value of the time from the last activation is exceeded. At the time of the activation of the trigger both these values are zeroed. If the method does not use a flash-lamp interface, all data is recorded at the time of the trigger activation. If the method uses a flash-lamp interface, all data is recorded at the time of triggering the shutter, and simultaneously the time between the activation of the trigger and of the shutter is recorded. The automatic mode operates based on the previously uploaded settings (configured by the PC software) and requires no additional control signals. The semi-automatic mode also operates based on the previously uploaded settings (configured by the PC software). Additionally, this mode allows the user to activate or deactivate a channel by PWM signal.

For both modes the PC software can be used to set up 3 parameters: duration of trigger activation, interval between successive activations and distance between the successive activations. The last two values are the criteria for the activation of the camera 2. By modifying these parameters one can freely adjust the degree of longitudinal overlap of photographs.

PWM signals are used for triggering. There are 3 control modes of applying the method: with an autopilot (via a software in the unmanned aircraft), in the manual mode (human operator equipped with a remote control device) and via another device that can send PWM signals to the trigger based on the preset criteria. Cameras available on the market most often employ a triggering interface that involves connecting the signal line with the ground. The trigger 1 is connected to the camera 2 with such an interface. Optionally, the trigger 1 is additionally connected to the camera 2 via a flash-lamp interface so as to enable accurate measurement of the delay between the activation of the trigger and the shutter. Any device that generates PWM signals can be used to control the trigger 1 (in the semi-automatic or manual mode). The PWM standard is used, in which the pulse length is between 1000 and 2000 μ5. The method uses the following standardisation - high PWM signal corresponds to the pulse length greater than 1200 με, and low PWM signal corresponds to the pulse length lower than 1200 μ≤. In the semi-automatic and manual mode the trigger 1 is activated by providing the high signal on the PWM input of the respective channel (camera). When the high signal is detected in the semiautomatic mode, a (preset) triggering program is activated. When the low signal is detected the triggering is stopped. When the high signal is detected in the manual mode, the trigger is activated, and when the low signal is detected, the trigger is deactivated.