SDK Core Utils

class Metavision::CDFrameGenerator

Utility class to display CD events that handles multithreading and is built on the top of PeriodicFrameGenerator.

Public Functions

CDFrameGenerator(long width, long height, bool process_all_frames = false)

Default constructor.

Parameters

width – Width of the image (in pixels)
height – Height of the image (in pixels)
process_all_frames – If true, it will process all frames, not just the latest one. Note that if true it can slow down the process.

~CDFrameGenerator(): Destructor.

void set_colors(const cv::Scalar &background_color, const cv::Scalar &on_color, const cv::Scalar &off_color, bool colored = false)

Sets the color used to generate the frame.

By default, the frame generated will be 8 bits single channel with the default colors grey, white, black as background, on and off colors respectively. If the parameter colored is false, then the generated frame will be 8 bits single channel and the first channel will be used to define each colors (i.e. the other channels will be ignored). If the parameter colored is true, then the generated frame will be 8 bits three channels.

Parameters

background_color – Color used as background, when no events were received for a pixel, default: grey cv::Scalar::all(128)
on_color – Color used for on events, default: white cv::Scalar::all(255)
off_color – Color used for off events, default: black cv:Scalar::all(0)
colored – If the generated frame should be single or three channels

void set_color_palette(const Metavision::ColorPalette &palette)

Sets the color used to generate the frame.

Parameters: palette – The Prophesee’s color palette to use

void add_events(const Metavision::EventCD *begin, const Metavision::EventCD *end)

Adds the buffer of events to be displayed.

Parameters

begin – Beginning of the buffer of events
end – End of the buffer of events

void set_display_accumulation_time_us(timestamp display_accumulation_time_us)

Sets the time interval to display events.

The events shown at each refresh are such that their timestamps are in the last ‘display_accumulation_time_us’ microseconds from the last received event timestamp.

Parameters: display_accumulation_time_us – The time interval to display events from up to now (in us).

bool start(std::uint16_t fps, const PeriodicFrameGenerationAlgorithm::OutputCb &cb)

Starts the generator thread.

Parameters

fps – Frame rate
cb – Function to call every time a new frame is available. It takes in input the time (in us) of the new frame and the frame. The frame passed as a parameter is guaranteed to be available and left untouched until the next time the callback is called. This means that you don’t need to make a deep copy of it, if you only intend to use the frame until the next one is made available by the callback.

Returns

true if the thread started successfully, false otherwise. Also returns false, if the thread is already started.

bool stop()

Stops the generator thread.

Returns: true if the thread has been stopped successfully, false otherwise. Return false if the thread had not been previously started

void reset(): Resets the frame generator state.

struct Metavision::RGBColor

Struct that represents a color in RGB colorspace.

Public Members

double r: a fraction between 0 and 1

double g: a fraction between 0 and 1

double b: a fraction between 0 and 1

struct Metavision::HSVColor

Struct that represents a color in HSV colorspace.

Public Members

double h: angle in degrees

double s: a fraction between 0 and 1

double v: a fraction between 0 and 1

inline RGBColor Metavision::hsv2rgb(HSVColor hsv)

Utility function to convert from HSV to RGB colorspace.

Parameters: hsv – A color in HSV colorspace
Returns: RGBColor the color converted in RGB colorspace

inline HSVColor Metavision::rgb2hsv(RGBColor rgb)

Utility function to convert from RGB to HSV colorspace.

Parameters: rgb – A color in RBB colorspace
Returns: HSVColor the color converted in HSV colorspace

enum class Metavision::ColorPalette

Enum class representing available color palettes.

Values:

enumerator Light

enumerator Dark

enumerator CoolWarm

enumerator Gray

enum class Metavision::ColorType

Enum class representing one of the possible type of colors.

Values:

enumerator Background

enumerator Positive

enumerator Negative

enumerator Auxiliary

inline const RGBColor &Metavision::get_color(const ColorPalette &palette, const ColorType &type)

Gets a color given a palette and the color type.

Parameters

palette – The requested color palette
type – The requested color type

Returns

The color associated to the given palette and type

inline const RGBColor &Metavision::get_color(const ColorPalette &palette, const std::string &name)

Gets a color given a palette and the color name.

Parameters

palette – The requested color palette
name – The requested color name

Returns

The color associated to the given palette and name

class Metavision::CvColorMap

Wrapper around cv::applyColorMap to avoid reallocating memory for the colormap at each call.

The colormap look-up-table is created only once, when the class is constructed. Then the parenthesis operator allows to apply it on an input image.

See implementation of “void ColorMap::operator()(InputArray _src, OutputArray _dst) const” in https://github.com/opencv/opencv/blob/master/modules/imgproc/src/colormap.cpp

Public Functions

inline CvColorMap(unsigned int cmap = 2)

Initializes the colormap.

Parameters: cmap – Colormap to apply. See cv::ColormapTypes. It’s cv::COLORMAP_JET by default

inline void operator()(const cv::Mat &src, cv::Mat &dst) const

Applies the colormap on a given image.

Parameters

src – Source image, grayscale or colored of type CV_8UC1 or CV_8UC3
dst – Result is the colormapped source image. Note: cv::Mat::create is called on dst

class Metavision::CvVideoRecorder

A simple threaded video recorder using OpenCV routines.

Public Functions

~CvVideoRecorder(): Records all remaining frames then destroys the object.

bool start(): Starts the recording thread.

void stop()

Stops adding data to the recording queue through the write methods.

The recorder thread remains active until all data added in the queue have been dumped.

Throws: cv::Exception – when an error occurs (e.g output file too big)

void write(cv::Mat &data)

Pushes the input frame for writing.

This method does nothing if the recorder thread is not active

bool is_recording(): Returns if the recording thread is ongoing.

class Metavision::VideoWriter : public VideoWriter 

Video writer class.

The class provides C++ API for writing video files or image sequences.

Note

This class fixes a bug in the OpenCV MJPEG encoder and it is recommended to use it over the original cv::VideoWriter.

Public Functions

VideoWriter(): Default constructors.

VideoWriter(const cv::String &filename, int fourcc, double fps, cv::Size frameSize, bool isColor = true)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Tips:

With some backends fourcc=-1 pops up the codec selection dialog from the system.
To save image sequence use a proper filename (eg. img_%02d.jpg) and fourcc=0 OR fps=0. Use uncompressed image format (eg. img_%02d.BMP) to save raw frames.
Most codecs are lossy. If you want lossless video file you need to use a lossless codecs (eg. FFMPEG FFV1, Huffman HFYU, Lagarith LAGS, etc…)
If FFMPEG is enabled, using codec=0; fps=0; you can create an uncompressed (raw) video file.

Parameters

filename – Name of the output video file.
fourcc – 4-character code of codec used to compress the frames. For example, VideoWriter::fourcc(‘P’,’I’,’M’,’1’) is a MPEG-1 codec, VideoWriter::fourcc(‘M’,’J’,’P’,’G’) is a motion-jpeg codec etc. List of codes can be obtained at Video Codecs by FOURCC page. FFMPEG backend with MP4 container natively uses other values as fourcc code: see ObjectType, so you may receive a warning message from OpenCV about fourcc code conversion.
fps – Framerate of the created video stream.
frameSize – Size of the video frames.
isColor – If it is not zero, the encoder will expect and encode color frames, otherwise it will work with grayscale frames.

VideoWriter(const cv::String &filename, int apiPreference, int fourcc, double fps, cv::Size frameSize, bool isColor = true): This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. The apiPreference parameter allows to specify API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_FFMPEG or cv::CAP_GSTREAMER.

VideoWriter(const cv::String &filename, int fourcc, double fps, const cv::Size &frameSize, const std::vector<int> &params): This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. The params parameter allows to specify extra encoder parameters encoded as pairs (paramId_1, paramValue_1, paramId_2, paramValue_2, … .) see cv::VideoWriterProperties

VideoWriter(const cv::String &filename, int apiPreference, int fourcc, double fps, const cv::Size &frameSize, const std::vector<int> &params): This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

virtual ~VideoWriter()

Default destructor.

The method first calls VideoWriter::release to close the already opened file.

virtual bool open(const cv::String &filename, int fourcc, double fps, cv::Size frameSize, bool isColor = true)

Initializes or reinitializes video writer.

The method opens video writer. Parameters are the same as in the constructor VideoWriter::VideoWriter.

The method first calls VideoWriter::release to close the already opened file.

Returns: true if video writer has been successfully initialized

bool open(const cv::String &filename, int apiPreference, int fourcc, double fps, cv::Size frameSize, bool isColor = true): This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

bool open(const cv::String &filename, int fourcc, double fps, const cv::Size &frameSize, const std::vector<int> &params): This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

bool open(const cv::String &filename, int apiPreference, int fourcc, double fps, const cv::Size &frameSize, const std::vector<int> &params): This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

virtual bool isOpened() const: Returns true if video writer has been successfully initialized.

virtual void release()

Closes the video writer.

The method is automatically called by subsequent VideoWriter::open and by the VideoWriter destructor.

virtual VideoWriter &operator<<(const cv::Mat &image)

Stream operator to write the next video frame.

See also

write

virtual void write(cv::InputArray image)

Writes the next video frame.

The function/method writes the specified image to video file. It must have the same size as has been specified when opening the video writer.

Parameters: image – The written frame. In general, color images are expected in BGR format.

virtual bool set(int propId, double value)

Sets a property in the VideoWriter.

Parameters

propId – Property identifier from cv::VideoWriterProperties (eg. cv::VIDEOWRITER_PROP_QUALITY) or one of videoio_flags_others
value – Value of the property.

Returns

true if the property is supported by the backend used by the VideoWriter instance.

virtual double get(int propId) const

Returns the specified VideoWriter property.

Parameters: propId – Property identifier from cv::VideoWriterProperties (eg. cv::VIDEOWRITER_PROP_QUALITY) or one of videoio_flags_others
Returns: Value for the specified property. Value 0 is returned when querying a property that is not supported by the backend used by the VideoWriter instance.

cv::String getBackendName() const: Returns used backend API name.

Note

Stream should be opened.

class Metavision::FrameComposer

This class implements an object capable of displaying a big image containing many images in an openGL window.

You need to first call method FrameComposer::add_new_subimage_parameters for each small image that you want to display in the big one. It will create an ImageParams object that will store the reference to the small image but also its position and other fields. Every time you call FrameComposer::update_subimage, FrameComposer will gather all ImageParams, put image at the right place in the big one and copy that in the output image.

Ideally the class takes integer pixels as inputs (CV_8UC1 or CV_8UC3). In case of floating point values, the cv::Mat is converted to an int type, which might slightly slow down the process.

Public Functions

inline FrameComposer(const cv::Vec3b &background_color = cv::Vec3b(0, 0, 0))

Constructor.

Parameters: background_color – Default color of the composition background (CV_8UC3)

inline ~FrameComposer(): Destructor.

inline unsigned int add_new_subimage_parameters(int top_left_x, int top_left_y, const ResizingOptions &resize_options, const GrayToColorOptions &gray_to_color_options)

Selects a sub-part of the final composed image and defines its preprocessing options.

Warning

It’s possible to define sub-images with overlapping regions of interests. Each update of a sub-image overwrites the corresponding subpart of the image, and thus also overwrites the overlapping areas. Thus, if a small sub-image is located on top of a larger sub-image, it will only be visible if its resfresh rate is larger than or equal to the one of the larger sub-image, and ist update with update_subimage is called at the end

Parameters

top_left_x – X-position of the top-left corner of the image in the composition
top_left_y – Y-position of the top-left corner of the image in the composition
resize_options – Options used to resize the image
gray_to_color_options – Options used to rescale and/or apply a colormap on the grayscale image

Returns

Reference (integer) of the sub-image to update later with update_subimage

inline bool update_subimage(unsigned int img_ref, const cv::Mat &image)

Update the sub-part of the final image corresponding to the reference img_ref.

Parameters

img_ref – Reference ID of the sub-image, defined in the function add_new_subimage_parameters
image – Image to display at the corresponding location in the full composed image If the type is different than CV_8UC3 or CV_8UC1, then a conversion is performed

inline const cv::Mat &get_full_image() const

Gets the full image.

Returns: The composed image

inline const int get_total_width() const

Gets width of the output image.

Returns: The width of the output image

inline const int get_total_height() const

Gets height of the output image.

Returns: The height of the output image

struct GrayToColorOptions

Settings used to rescale and/or apply a colormap on a grayscale image.

Public Members

unsigned char min_rescaling_value = 0: Min grayscale value for the rescaling.

unsigned char max_rescaling_value = 255: Max grayscale value for the rescaling.

int color_map_id = -1

Colormap to apply:

None = -1
COLORMAP_AUTUMN = 0
COLORMAP_BONE = 1
COLORMAP_JET = 2
COLORMAP_WINTER = 3
COLORMAP_RAINBOW = 4
COLORMAP_OCEAN = 5
COLORMAP_SUMMER = 6
COLORMAP_SPRING = 7
COLORMAP_COOL = 8
COLORMAP_HSV = 9
COLORMAP_PINK = 10
COLORMAP_HOT = 11

struct ResizingOptions

Settings used to resize or crop an image.

Public Members

const unsigned int height: New size of the image in the final composition.

const bool enable_crop: Whether to enable cropping the image to the specified width and height (maintains the center)

const InterpolationType interp_type: Type of interpolation used to resize images.

template<typename timestamp_type> class Metavision::MostRecentTimestampBufferT

Class representing a buffer of the most recent timestamps observed at each pixel of the camera.

A most recent timestamp buffer is also called time surface.

Note

The interface follows the one of cv::Mat

Public Functions

MostRecentTimestampBufferT(): Default constructor.

inline MostRecentTimestampBufferT(int rows, int cols, int channels = 1)

Initialization constructor.

Parameters

rows – Sensor’s height
cols – Sensor’s width
channels – Number of channels

inline MostRecentTimestampBufferT(const MostRecentTimestampBufferT<timestamp_type> &other)

Copy constructor.

Parameters: other – The timestamp buffer to construct from

inline virtual ~MostRecentTimestampBufferT(): Destructor.

inline void create(int rows, int cols, int channels = 1)

Allocates the buffer.

Parameters

rows – Sensor’s height
cols – Sensor’s width
channels – Number of channels

inline void release(): Deallocates the buffer.

inline int rows() const: Gets the number of rows of the buffer.

inline int cols() const: Gets the number of columns of the buffer.

inline cv::Size size() const: Gets the size of the buffer (i.e. Sensor’s size as well)

inline int channels() const: Gets the number of channels of the buffer.

inline bool empty() const: Checks whether the buffer is empty.

inline void set_to(timestamp_type ts)

Sets all elements of the timestamp buffer to a constant.

Parameters: ts – The constant timestamp value

inline void copy_to(MostRecentTimestampBufferT<timestamp_type> &other) const

Copies this timestamp buffer into another timestamp buffer.

Parameters: other – The timestamp buffer to copy to

inline void swap(MostRecentTimestampBufferT<timestamp_type> &other)

Swaps the timestamp buffer with another one.

Parameters: other – The timestamp buffer to swap with

inline const timestamp_type &at(int y, int x, int c = 0) const

Retrieves a const reference of the timestamp at the specified pixel.

Parameters

y – The pixel’s ordinate
x – The pixel’s abscissa
c – The channel to retrieve the timestamp from

Returns

The timestamp at the given pixel

inline timestamp_type &at(int y, int x, int c = 0)

Retrieves a reference of the timestamp at the specified pixel.

Parameters

y – The pixel’s ordinate
x – The pixel’s abscissa
c – The channel to retrieve the timestamp from

Returns

The timestamp at the given pixel

inline const timestamp_type *ptr(int y = 0, int x = 0, int c = 0) const

Retrieves a const pointer to the timestamp at the specified pixel.

Parameters

y – The pixel’s ordinate
x – The pixel’s abscissa
c – The channel to retrieve the timestamp from

Returns

The timestamp at the given pixel

inline timestamp_type *ptr(int y = 0, int x = 0, int c = 0)

Retrieves a pointer to the timestamp at the specified pixel.

Parameters

y – The pixel’s ordinate
x – The pixel’s abscissa
c – The channel to retrieve the timestamp from

Returns

The timestamp at the given pixel

inline timestamp_type max_across_channels_at(int y, int x) const

Retrieves the maximum timestamp across channels at the specified pixel.

Parameters

y – The pixel’s ordinate
x – The pixel’s abscissa

Returns

The maximum timestamp at that pixel across all the channels in the buffer

inline void generate_img_time_surface(timestamp_type last_ts, timestamp_type delta_t, cv::Mat &out) const

Generates a CV_8UC1 image of the time surface for the 2 channels.

Side-by-side: negative polarity time surface, positive polarity time surface The time surface is normalized between last_ts (255) and last_ts - delta_t (0)

Parameters

last_ts – Last timestamp value stored in the buffer
delta_t – Delta time, with respect to last_t, above which timestamps are not considered for the image generation
out – The produced image

inline void generate_img_time_surface_collapsing_channels(timestamp_type last_ts, timestamp_type delta_t, cv::Mat &out) const

Generates a CV_8UC1 image of the time surface, merging the 2 channels.

The time surface is normalized between last_ts (255) and last_ts - delta_t (0)

Parameters

last_ts – Last timestamp value stored in the buffer
delta_t – Delta time, with respect to last_t, above which timestamps are not considered for the image generation
out – The produced image

class Metavision::RateEstimator

Simple estimator class that can estimate average and peak rate online from sample counts.

This class estimates average and peak rate according to the added samples using the peak, step and window time durations as follows :

the average rate is the mean event rate computed over the samples added during last window duration
the peak rate is the maximum event rate of the estimated rates computed over subwindows of peak duration during last window duration (thus, peak duration must always be less or equal to window duration)

The average and peak rate are then output via a callback which is called :

every step duration of system time, if system_time_flag is true
everytime a sample with a timestamp > (last callback time + step duration) is added, if system_time_flag is false

Note

Every duration must be expressed in microseconds.

Warning

This class is not protected against concurrent accesses and does not provide thread safe functions

Public Types

using Callback = std::function<void(timestamp, double, double)>: Callback type to be used in the constructor.

Public Functions

RateEstimator(const Callback &cb = Callback(), timestamp step_time = 100000, timestamp window_time = 1000000, bool system_time_flag = false)

Constructor.

This constructor sets peak_time = step_time

Parameters

cb – Callback that will be called with the current timestamp, estimated average and peak rates over the counts added in the window_time span
step_time – Minimum period between two successive callbacks
window_time – Time window used to compute the average and peak rates
system_time_flag – If true, the callback will be called when the sytem time becomes higher than current multiple of step_time, otherwise the sample time is used

RateEstimator(timestamp step_time, timestamp window_time, timestamp peak_time, const Callback &cb, bool system_time_flag = false)

Constructor.

Parameters

step_time – Minimum period between two successive callbacks
window_time – Time window used to compute the average and peak rates
peak_time – Time window used to estimate peak rates
cb – Callback that will be called with the current timestamp, estimated average and peak rates over the counts added in the window_time span
system_time_flag – If true, the callback will be called when the sytem time becomes higher than current multiple of step_time, otherwise the sample time is used

void add_data(timestamp time, size_t count)

Adds a sample count at t = time.

The callback will be called with estimated rates from the available sample counts in the window timespan, if :

system_time_flag = true and the sample count added has a time time > next_time (next_time = last_callback_sample_time + step_time)
system_time_flag = false and the function is called with a system time > next_time (next_time = last_callback_sytem_time + step_time)

Note

this function must be called with the same time used at last call (the count will then be added to the previous one) or with a time greater than the previous one

Parameters

time – Time of the sample
count – Count of the sample

void reset_data(): Reset all sample counts.

timestamp step_time() const

Get the minimum time between two callbacks.

Returns: The step time

timestamp window_time() const

Get the window duration on which average and peak rates are computed.

Returns: The window time

timestamp peak_time() const

Get the peak duration on which peak rates are computed.

Returns: The peak time

class Metavision::SimpleDisplayer

Class representing a simple displayer.

Public Functions

SimpleDisplayer(const std::string window_name, int fps = 50)

Constructor.

Parameters

window_name – Name of the window to display
fps – Frames per second to display

~SimpleDisplayer() = default: Default destructor.

void stop(): Quits the display.

void swap_frame(cv::Mat &frame)

Updates the current frame by swap.

Parameters: frame – Frame to swap

void copy_frame(const cv::Mat &frame)

Updates the current frame by copy.

Parameters: frame – Frame to copy

void set_on_key_pressed_cb(const OnKeyPressedCb &on_key_pressed_cb)

Sets the callback that is called when a key is pressed.

Parameters: on_key_pressed_cb – Function to call

void run(): Runs the displayer. Should be called in the main thread.

class Metavision::ThreadedProcess

A convenient object whose purpose is to queue and dequeue tasks in a thread.

Public Functions

~ThreadedProcess()

Destructor.

Waits for all pending tasks completion before leaving the thread. Use abort before destruction to abort the processing.

void add_task(Task task): Adds a task to the processing queue.

void add_repeating_task(RepeatingTask task): Adds a task that is repeated once it is done if and only if its result returns true.

bool start()

Starts the processing thread.

Returns: false if the processing thread is already started

void stop()

Requests the processing thread to stop and join.

The processing thread remains active until all pending tasks have been processed

void abort()

Requests the processing thread to abort and join.

The threads leaves when it is no longer processing a task. All remaining tasks are dropped.

bool is_active(): Returns if the processing thread is ongoing.

class Metavision::DataSynchronizerFromTriggers

The purpose of this class is to synchronize with the event-stream the data from an external source generating external triggers.

Synchronization information is generated from the input triggers events. This information contains a timestamp (the one of the trigger used to generate it) and an index. The indexes are guaranteed to be strictly and incrementally increasing from a starting value (0 by default). However, some triggers may be lost for various reasons, as a consequence the indexes are generated using both input triggers’ timestamp and the expected period of the external data: -> index_increment = (trigger_ts - previous_trigger_ts)/period.

The synchronization is done by matching indexes generated from the triggers with the ones provided by the external data streams. When a data’s index finds a match, its timestamp takes the value of its match.

This class interpolates synchronization information if triggers are missing (i.e. index_increment > 1). This is to guarantee that all data to synchronize can find a match. -> interpolated_ts = previous_trigger_ts + period

Only one polarity is used for the synchronization (i.e. up or down, chosen by the user) as it is considered that each external data generates a pair of triggers (i.e. one data for two triggers).

The synchronization routines are blocking and thread safe.

Warning

This class considers that the input stream of triggers is periodic and that the period doesn’t change at runtime.

Warning

It is assumed here that the source of external triggers is the same as the external data’s one

Public Functions

DataSynchronizerFromTriggers(const Parameters &parameters)

Constructor.

Parameters: parameters – The Parameters to use to configure this object.

~DataSynchronizerFromTriggers(): Destructor Sets the triggers source as done to unlock the synchronization if it is waiting.

void reset_synchronization(): Resets the synchronization states variables. Unlocks any pending synchronization before clearing the synchronization information remaining to be used.

void set_synchronization_as_done()

Notifies this object that the synchronization is done.

This means that either the trigger source and thus no trigger is to be received anymore, or that the external data stream won’t use triggers anymore

This unlocks pending synchronization and forbids indexing of new triggers.

template<typename ExtTriggerIterator> size_t index_triggers(ExtTriggerIterator trigger_it, ExtTriggerIterator trigger_it_end)

Generates SynchronizationInformation from the external triggers input stream.

This information is to be used for the synchronization (synchronize_data_from_triggers). This method is not blocking: this is not a synchronization point.

Warning

ExtTriggerIterator must be an iterator over EventExtTrigger

Template Parameters

ExtTriggerIterator – The type of the external trigger input events iterator

Parameters

trigger_it – The first iterator to an external trigger to process
trigger_it_end – The last iterator to an external trigger to process

Returns

The number of external triggers that have been updated

template<typename ExtTriggerIterator, typename IndexTriggerInserterIterator> void index_triggers(ExtTriggerIterator trigger_it, ExtTriggerIterator trigger_it_end, IndexTriggerInserterIterator indexed_trigger_inserter_it)

Generates SynchronizationInformation from the external triggers input stream.

This information is to be used for the synchronization (synchronize_data_from_triggers). This method is not blocking: this is not a synchronization point.

Warning

ExtTriggerIterator must be an iterator over EventExtTrigger

Template Parameters

ExtTriggerIterator – The type of the external trigger input events iterator

Parameters

trigger_it – The first iterator to an external trigger to process
trigger_it_end – The last iterator to an external trigger to process
indexed_trigger_inserter_it – An iterator to insert all triggers used to generate synchronization information

template<typename DataIterator> uint32_t synchronize_data_from_triggers(DataIterator data_it, DataIterator data_it_end, std::function<timestamp&(detail::value_t<DataIterator>&)> data_timestamp_accessor, std::function<uint32_t(const detail::value_t<DataIterator>&)> data_index_accessor)

Synchronizes indexed data with the generated SynchronizationInformation from method index_triggers.

Warning

It is assumed here that the source of external triggers is the same as the external data source

Warning

It is assumed here that the data source to be synchronized has been indexed before the call.

Warning

It is assumed here that the data source’ indices are strictly increasing otherwise this may break the synchronization procedure.

Warning

Timestamp of input data source must be accessible and modifiable.

Warning

Index of input data source must be accessible.

Template Parameters

DataIterator – The input data’s iterator type

Parameters

data_it – The first iterator to the data to synchronize. Each data is accessed and modified.
data_it_end – The last iterator to the data to synchronize.
data_timestamp_accessor – A cb to access the timestamp of the input data. Timestamp must be modifiable.
data_index_accessor – A cb to access the index of the input data. Neither the index nor the data is modified.

Returns

The number of synchronized data. This amount is usually the same as std::distance(data_it, data_it_end) unless we stopped receiving triggers.

void wait_for_triggers_consumed(uint32_t max_remaining_to_be_consumed = 0)

Indicates the maximum number of external triggers that can be pending to be used for synchronization.

This can be used to slow down an event-based data polling thread

Parameters: max_remaining_to_be_consumed – The maximum number of pending external triggers

struct Parameters

Parameters to be used to configure the DataSynchronizerFromTriggers.

Public Members

double periodicity_tolerance_factor_ = {0.1}: Used to compute the time interval around the expected trigger’s timestamp. If the timestamp falls before this range, the trigger is considered to be a duplicate and is not used. Though this should not happen.

uint32_t period_us_: Triggers’ pair period i.e. expected dt between two triggers of the same polarity.

uint32_t to_discard_count_ = {0}: Number of triggers to discard from the beginning of the external triggers.

uint32_t index_offset_ = {0}: This is the very first data to synchronize expected index and so the first trigger index.

bool reference_polarity_ = {0}: The trigger’s polarity to use.

struct SynchronizationInformation

Synchronization information data used to timestamp a piece of external data using an external trigger and the index of the piece of external data.

Public Members

timestamp t: Timestamp of the trigger used to generate this.

uint32_t index: Index computed from the triggers timestamps.

class RawEventFrameConverter

struct Metavision::RollingEventBufferConfig

Configuration structure for the RollingEventBuffer class.

Public Members

RollingEventBufferMode mode: Mode of the rolling buffer.

timestamp delta_ts: Time slice duration in microseconds (for N_US mode)

std::size_t delta_n_events: Number of events to store (for N_EVENTS mode)

Public Static Functions

static inline RollingEventBufferConfig make_n_us(timestamp n_us)

Creates a RollingEventBufferConfig for the N_US mode.

Parameters: n_us – Time slice duration in microseconds
Returns: a RollingEventBufferConfig for the N_US mode

static inline RollingEventBufferConfig make_n_events(std::size_t n_events)

Creates a RollingEventBufferConfig for the N_EVENTS mode.

Parameters: n_events – Number of events to store
Returns: a RollingEventBufferConfig for the N_EVENTS mode

template<typename T> class Metavision::RollingEventBuffer

A rolling buffer that can store events based on a fixed duration or a fixed number of events.

This class provides a rolling buffer capable of storing events. It can operate in two modes: fixed duration (N_US) or fixed number of events (N_EVENTS). In the N_US mode, the buffer automatically adjusts its size to store events corresponding to a fixed-duration time slice. In the N_EVENTS mode, it stores a fixed number of events, replacing the oldest events when new ones arrive.

Template Parameters: T – The type of events to store in the buffer

Public Functions

RollingEventBuffer(const RollingEventBufferConfig &config = RollingEventBufferConfig::make_n_events(5000))

Constructs a RollingEventBuffer with the specified configuration.

Parameters: config – The configuration for the rolling buffer

RollingEventBuffer(const RollingEventBuffer &other)

Copy constructor.

Parameters: other – The instance to copy

RollingEventBuffer(RollingEventBuffer &&other)

Move constructor.

Parameters: other – The instance to move

RollingEventBuffer &operator=(const RollingEventBuffer &other)

Copy assignment operator.

Parameters: other – The instance to copy
Returns: *this

RollingEventBuffer &operator=(RollingEventBuffer &&other)

Move assignment operator.

Parameters: other – The instance to move
Returns: *this

template<typename InputIt> void insert_events(InputIt begin, InputIt end)

Inserts events into the buffer.

This function inserts events into the buffer based on the current mode (N_US or N_EVENTS)

Template Parameters

InputIt – Iterator type for the events

Parameters

begin – Iterator pointing to the beginning of the events range
end – Iterator pointing to the end of the events range

size_t size() const

Returns the current number of events stored in the buffer.

Returns: The number of events stored

size_t capacity() const

Returns the maximum capacity of the buffer.

Returns: The maximum capacity of the buffer

bool empty() const

Checks if the buffer is empty.

Returns: true if the buffer is empty, false otherwise

void clear(): Clears the buffer, removing all stored events.

const T &operator[](size_t idx) const

Accesses events in the buffer using the [] operator.

Parameters: idx – idx The index of the event to access
Returns: A reference to the event at the specified index

T &operator[](size_t idx)

Accesses events in the buffer using the [] operator.

Parameters: idx – idx The index of the event to access
Returns: A reference to the event at the specified index

iterator begin()

Returns an iterator pointing to the beginning of the buffer.

Returns: An iterator pointing to the beginning of the buffer

iterator end()

Returns an iterator pointing to the end of the buffer.

Returns: An iterator pointing to the end of the buffer

const_iterator begin() const

Returns a const iterator pointing to the beginning of the buffer.

Returns: A const iterator pointing to the beginning of the buffer

const_iterator end() const

Returns a const iterator pointing to the end of the buffer.

Returns: A const iterator pointing to the end of the buffer

const_iterator cbegin() const

Returns a const iterator pointing to the beginning of the buffer.

Returns: A const iterator pointing to the beginning of the buffer

const_iterator cend() const

Returns a const iterator pointing to the end of the buffer.

Returns: A const iterator pointing to the end of the buffer

template<typename T1, typename T2> inline float Metavision::Utils::intersection(const T1 &box1, const T2 &box2)

Computes intersection area of two boxes.

Parameters

box1 – Description of a 2D box
box2 – Description of a 2D box

Returns

proportion of intersection area

template<typename T1, typename T2> inline float Metavision::Utils::intersection_over_union(const T1 &box1, const T2 &box2)

Computes the ratio between intersection area and union area.

Parameters

box1 – Description of a 2D box
box2 – Description of a 2D box

Returns

Proportion of intersection area

template<typename T1, typename T2> inline float Metavision::Utils::compute_similarity_iou_using_classid(const T1 &box1, const T2 &box2)

Helper function to compute similarity, taking into account the class.

Parameters

box1 – Description of a 2D box
box2 – Description of a 2D box

Returns

Proportion of intersection area if class ID are the same, 0 otherwise

template<typename T1, typename T2> inline float Metavision::Utils::compute_similarity_iou_using_classid_and_similarity_matrix(const T1 &box1, const T2 &box2, const std::vector<float> &similarity_matrix, unsigned int nb_object_classes)

Helper function to compute similarity, taking into account the class and a similarity matrix

Parameters

box1 – Description of a 2D box
box2 – Description of a 2D box
similarity_matrix – (nb_object_classes + 1) x (nb_object_classes + 1) matrix of similarity weights.
nb_object_classes – Number of valid object classes. class_id 0 is ‘background’ class and is not counted as a valid object class

Returns

Weighted proportion of intersection area (weights depends on class id)