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System-defined Properties

ApertureDB defines a set of properties known as system-defined properties. These properties are either used in object definitions or computed internally by the system. To distinguish them from user-defined properties, all system-defined properties start with “_” prefix. Some properties are present in all objects (e.g., _uniqueid), while others are specific to certain object types (e.g., _label for BoundingBox, Polygons, or Descriptors). System-defined properties cannot be updated by users, except in cases where the Update command explicitly supports modification through defined parameters. However, these properties can be used as keys in constraints.

Here we detail the set of properties for each Object:

Object

Properties

Type

Param for Update Command

Can Be Used in constraints

Notes

All Objects

_uniqueid

string

Y

Unique id for the object

_create_txn

number

Y

Transaction id that created the object

Connection

_src

string

N

unique_id of the src of the connection

_dst

string

N

unique_id of the dst of the connection

DescriptorSet

_name

string

Y

Name of the set

_dimensions

number

Y

Dimensionality of the Descriptors

_engines

array

N

List of engines available for KNN

_metrics

array

N

List of metrics available for KNN

_count

number

Y

Number of Descriptors in the Set

_segment_size

number

Y

Number of Descriptors on each segment

_max_segments

number

Y

Maximum number of segments

_splits

object

N

Number of splits

Descriptor

_label

string

label

Y

_set_name

string

Y

Name of the set the Descriptor belongs to

BoundingBox

_label

string

label

Y

_coordinates

rect

rectangle

N

_area

number

Y

Area (in pixels) of the BoundingBox

Polygon

_label

string

label

Y

_vertices

poly

polygons

N

_area

number

Y

Area (in pixels) of the Polygon

_bounds

rect

N

The smallest rectangle containing the Polygon

Video

_fps

number

Y

Average frames per second

_frame_count

number

Y

Number of frames in the video

_frame_width

number

Y

Width of the frame

_frame_height

number

Y

Height of the frame

Frame

_label

string

label

Y

_frame_number

number

frame_number

Y

_time_offset

string

time_offset

Y

_time_fraction

number

time_fraction

Y

Clip

_label

string

label

Y

_range_type

number

Y

Type describing what type of range (time,frame,pct)

_range_start

number

Y

Start of Clip range

_range_stop

number

Y

End of Clip range

NOTE: Only properties having ‘Param for Update Command’ are modifiable by the user.

NOTE: Only the “==” and “in” operators are supported for “_uniqueid”.