The subject of the invention is a method for downloading data from multiple cameras for omnidirectional image recording, and a device for downloading data from multiple cameras for omnidirectional image recording, used to download the data from data from multiple cameras at once. A set of multiple cameras may create an omnidirectional camera, a multiview camera or a light field camera. A special case of such a unit is an omnidirectional camera built from action cam type video recorders, used for omnidirectional recording.

Fragments of the description were presented as logical operations and data processing steps performed on data bits in the memory of data processing devices, e.g. computers.

It should be understood that the logical operations and data processing steps performed on data bits in the memory of data processing devices are implemented by physical devices which perform operations and steps on physical values or operate with physical items, or their condition or conditions.

Typical physical values used to record logical information such as data bits are various forms of electric or magnetic signals, which may be stored, transferred, transmitted, combined, compared or subjected to other physical activities in a calculating system, such as a computer.

Due to their common use such signals will be called bits, packets, messages, values, symbols, signs, numbers and other names, which should be always interpreted as representations, physical values and actions performed on these physical values by physical devices. Additionally these words are used only as convenient substitutes for appropriate values and physical processes. Names such as processing, generating, transmitting, performing, mapping, selecting, calculating, generating and others refer to physical processes and activities performed by physical devices (processing systems) which operate on data and transform data, represented by physical (electrical) signals in the records and memory of a processing system into other data which are also represented by physical values in the records and memory of the processing system or other data storage system using physical values.

The computer memory, memory, data card typically refer to a device which enables the storage of a set of states (information, data bits) in the form of electrical signals or changes to other physical state of this device and enables the multiple measurements of this condition (reading the information, data, bits).

The sets of cameras are frequently constructed from relatively cheap and mass produced„action cam" type cameras. An example of such camera is the GoPro Hero 3 Black camera. These cameras record a moving image in a built-in internal memory or as in the case of the mentioned earlier GoPro camera, on a memory card entered in an appropriate slot in the camera.

The cameras may record the images or video on a memory card such as the SD card [https://en.wikipedia.org/wiki/Secure_Digital], miniSD or microSD [http://www.dtt8.com images/micro-sd%20specification.pdfj standard.

Another popular memory card standard used in cameras is the MMC standard [http://www.jedec.org/sites/default/files/docs/JESD84-B41.pd fj. Some cameras use CF memory cards [http://www.compactflash.org/].

The cameras are equipped with an Universal Serial Bus (USB) [https://pl.wikipedia.org/wiki/USB] and a computer connector (port or interface) compatible with the USB standard used to connect the camera to other devices.

The USB architecture consists of an USB host, multiple USB ports and connected devices. The USB host may manage multiple controllers, and each controller may make one or more USB ports available. These devices may be connected creating a tree topology network by using USB hubs. They may be cascade-connected, creating an up to five level tree structure. The entire network may be used to connect up to 127 USB devices, however due to the power draw their number has to be limited. Each device communicates with the controller using up to 32 logic channels, of which 16 are input channels and 16 output channels. Two channels, one for each transmission direction are reserved, so there are 30 actual logic channels per each connected USB device. A single USB network may be used by devices with various transmission speeds.

USB standard compatible devices may be divided into three groups for reasons of compatibility with the assumed USB standard specifications: - USB 1.1 standard compatible devices; devices which meet the conditions forthis specification may operate at (Full Speed) 12 Mbit/s (1.5 MB/s) and (Low Speed) 1.5 Mbit/s (0.1875 MB/s).

- USB 2.0 (Hi-Speed) standard compatible devices; devices which are compatible with the USB 2.0 specification can transmit data at a maximum rate of 480 Mbit/s (60 MB/s). Actual data transmission rate depends on the device design and according to independent tests conducted by the CNet website [http.V/www.cnet.com/products/seagate-freeagent-goflex-ultra -portable/2/] the maximum write speed is in the range of 25 to 30 MB/s, and read speed from 30 to 42 MB/s. The USB 2.0 standard devices are fully compatible with the older standard devices.

Most of the cameras available on the market, in particular„action cam" type cameras are devices compatible with USB 1.1 or USB 2.0 standard, however the data transmission rate is limited to 10 MB/s [http://www.goprofanatics.com/forum/gopro-hd-hero3/2496-usb~ transfer- rate.html].

To accelerate the downloading of data recorded by the camera, usually the memory card is removed from the camera and the data is read directly by a memory card reader instead of connecting the camera to the computer by an USB. For example the use of dedicated card readers enables the reading of data from an SD memory card at a speed of 20 MB/s in case of an USB 2.0 compatible memory card reader [https ://www.pugetsystems.com/labs/articles/Card-Reader- Comparison-USB-2-0-vs-USB-3-0- 126/].

The USB in the cameras is also used for device charging. Standard power supply voltage for a single USB 1.1 or 2.0 compatible device is 5 V, whereas the specification defines conformance range of 4.75 V to 5.25 V [http://www.usb.org/developers/docs/usb20_docs/]. For USB 2.0 port the basic power supply unit is 100 mA, and these are the minimum values of the current which may be supplied by the port. At a standard power supply voltage the current in the circuit is 5 times higher and reaches 500 mA.

The USB specification in 2007 defined a new type of ports used for the charging of device batteries, called charging ports. They enable obtaining supply currents exceeding 500 mA without any negotiations with the controller, due to the possibility of interference the maximum supply current was limited to 900 mA. Whereas for dedicated charging ports the maximum current value which may be supplied by the port reaches 1.5 A.

Regardless of the USB standard version, the specification defines a series of USB device classes [http://www.usb.org/developers/docs/devclass__docs/] which specifies the details for communication with a given class of a device. One of the classes is a Mass Storage Class [https://en.wikipedia.org/wiki/USB_mass_storage_device_class ] commonly used in mass storage and pendrive devices. A mass storage class device provides access to its internal memory to the host device to which it is connected, enabling the host device to operate directly on the data recorded in the internal memory of the mass storage class device in the same manner as on data recorded directly in the host device memory.

Memory which is made available by mass storage class devices is mounted, that is, logically connected, and makes available the file system recorded in the memory, which is manipulated by the operating system. Logically mounted memory is made available as a contents of the folder where it was mounted.

The operating system [https://en.wikipedia.org/wiki/Operating_system] is software for the management of a computer system (processing unit), which generates a logical environment to start and control user tasks which are executed by the system.

Thread should be understood as a part of the computer software which is executed by the computer (processing unit) concurrently with other tasks performed by the computer. Usually each thread is executed by a different hardware fragment of the computer's processor, a different processor core.

The term„data downloading" should be understood as the process of copying and transfer of information between the memory of one device and the memory of another device.

Simultaneous operation of multiple cameras installed in a common holder or set of holders generates significant problems related to the downloading of the data recorded by the camera to a single computer or mass storage device, such as a RAID. In particular the significant problems include:

- the need of removing the memory cards from cameras before downloading

- subsequent connections of all cameras from the set to a computer or a mass storage device in case of cameras with no replaceable memory cards (built in memory)

- the need to charge the camera batteries before commencing the download of data (using the USB port)

- time needed to copy the data from all of cameras.

The device according to the invention enables the copying of data from all the cameras of the set without necessity of removing the cameras from the grip or set of grips every time, nor to remove memory cards from the cameras. A method according to the invention enables the shortening of the time needed to download the data from a set of cameras to a computer or mass storage device compared to the downloading (transmission) of data from cameras through an USB to a computer.

Currently downloading the data from a set of multiple cameras usually requires removing the memory card from each camera and to laboriously read their data one after another. Typically the download is performed by connecting cameras in a sequence to a computer through an USB and downloading the data, or by removing data cards from the cameras and reading the memory cards using dedicated card readers [https://en.wikipedia.org/wiki/Card_reader].

There are devices on the market which are based on USB hubs, which enable connecting 4 to 10 card readers to the computer, eliminating the need for arduous swapping of memory cards and enable the simultaneous connection of 4 to 10 memory cards to the computer.

Another popular solution for the problem of downloading data from multiple cameras is the use of an USB hub and/or many USB hosts, enabling the connection of multiple cameras to the computer. In this case multiple devices or mass storage devices are visible to the computer operating system, enabling the downloading (copying) of data from connected cameras. This solution requires a sequential initiation of connections (logical connections at the operating system level) with subsequent cameras in order to download the data recorded by the cameras.

The essence of the invention which is a device for downloading data from multiple cameras consists of each camera being connected by an USB to a device according to the invention, hereinafter referred to as the integrator. The integrator (software embedded in the integrator executed by the device processor) opens a connection to each of the connected cameras. The integrator software connects to each of the cameras and mounts the memory resource provided by the camera in its own memory. Thereafter the integrator makes the folder with mapped memories of individual cameras of the set available using a dedicated USB port as a mass storage device to the user's computer. The software according to the invention installed on the user's computer opens a connection to the integrator using the USB protocol. This software starts N independent threads, one each of N cameras connected to the integrator and downloads the data from each camera connected in parallel to the integrator.

Since the device connected to the user's computer may draw only a limited amount of current (typically the USB controller supplies 2 A of current at a voltage of 5 V), the device uses a system of current limiters, which reduces the maximum current draw by the cameras connected to the device. The essence of the Invention, which is a method for downloading of data from multiple cameras consists of the cameras being connected to USB ports of the integrator, whereas the charging current of each of the cameras connected to the integrator is limited, then a connection being opened to each of the cameras connected to the integrator and the memories made available by individual cameras are mounted as sub-folders of a dedicated folder, after which the dedicated folder is made available and the integrator is connected by an USB cable to a computer's USB port and a connection is started with the integrator, where N threads are started and data are downloaded from the folders made available by the cameras and mapped by the integrator in N threads.

It is advantageous when the number of cameras connected to the integrator is higher than the amount of started threads.

It is also advantageous when the number of started threads equals 1.

It is also advantageous when the memories made available by individual cameras are mounted as sub-folders of a dedicated folder with names which unequivocally identify the number of the connected camera.

It is also advantageous when the memories made available by individual cameras are mounted as sub-folders of a dedicated folder with names which unequivocally identify the number of USB port to which the given camera was connected.

This method is implemented in a device for downloading data from multiple cameras according to the invention, the essence of which consists of a set of cameras being connected directly through USB ports to an integrator, which opens a connection with each of the cameras and mounts the memory resource which is made available by the camera as a sub-folder of the main folder, after which the main folder with mapped sub-folders is made available to the user's computer through an USB port.

It is advantageous when current limiters are installed in the USB line between the integrator and the cameras.

The use of the solution presented in the invention enables the following technical and utility effects:

- the possibility of simultaneous reading of images from multiple cameras without having to remove a memory card from the camera, - limiting the maximum current supplied to the cameras by the user's computer,

- increasing the camera system's data download speed,

- the problem of simultaneous downloading of data from a set of multiple cameras was solved, while powering the system solely from the user's computer USB port.

The subject of the invention, in an example, but not limiting, implementation was presented in diagram on the figure.

A device according to the invention called integrator 1 composed of an SBC (single board computer) 1A, two USB hosts (IB and 1C), hub ID and current limiters IE. The cameras 2 are connected directly to the hub ID using the USB cable 3. The integrator 1 software executed by the processor of the SBC computer 1 A opens a connection to each of the cameras 2 and mounts the memory resource made available by the camera 2 as a sub-folder 3 of a separate folder 4 (drawing of the memory system). There is a possibility where each of the sub-folders identifies in an unequivocal manner the number of the camera, which enables simple processing of data recorded by individual cameras on subsequent stages of processing.

The integrator 1 makes available the main shared folder 4 with the mapped sub-folders 3 as a mass storage device, through a controller 1C and an USB connection 5 to the user's computer 4 to which it was connected.

Since the integrator connected to the computer may draw only a limited amount of current (typically the USB controllers allows the drawing of up to 2 A of current at 5 V). Moreover typically the camera 2 when connected to a computer or another device with an USB connector tries to switch to a charging mode and requests a large charging current (typically 750-900 mA). In case of connection of N cameras to the integrator 1 the total current required by cameras 2 would amount to N x the current requested by a single camera, while the integrator 1 may draw from the user's computer 4 a current which allows only to supply only a single camera (a max. of 2 A at 5 V). To solve this problem in the integrator 1 between the USB hub ID and the cameras 2 current limiters IE were placed, which limit the maximum current supplied to cameras 2.