CAMS

h1. Working with the database

The feature database is CAMS managing the storage and access of vector data, pieces of information like sensor measurements that can be described in space with a geometric figure such as a points, lines or polygons. See http://wiki.gis.com/wiki/index.php/Vector_data_modelto read more about vector data models.

The basic piece of information of this data model is the _feature_, defined by a _geometry_ that indicates unequivocally its position and shape in the world, and a set of _attributes_ which are the characteristics associated to that location. Related features sharing a common geometry definition and attribute set are usually grouped together.

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h2. Data model

The CAMS database model is takes inspiration from the _OGR data model_ and the _OGC OpenPackage specification_.

h3. Dataset

A dataset is encompasses a set of feature collections stored in the same database or file.

h3. Collection

A collection describes the characteristics of features of the same kind or category. I.e.: "Wind", "UAV state", "Liquid water content", etc. It corresponds roughly to a table in a relational database or a layer in many geographic information models.

A collection is defined by the following parameters:

# A computer id (name_id),

# A human-readable name,

# An coordinate reference system as an "EPSG code":https://en.wikipedia.org/wiki/EPSG_Geodetic_Parameter_Dataset,

# A geometry type (As of 12/2020 only the "point" geometry is supported),

# A ordered set of attributes and corresponding types,

# And, optionally, a long description.

h3. Feature

!vector_feature.png!

The collection field is used to identify the collection to with a particular field belongs and determines the geometry and attribute types. 

Feature attributes can be of type _int_, _str_, _float_, or _datetime_.

General attributes, *t* (time) and *producer* , are mandatory for features generated repeatedly by UAV sensors and are common for features of all collections. The time attribute is represented by a date and time (datetime.datetime in python) in Coordinated Universal Time (UTC). The producer attribute is a string.

Specific attributes are unique to a particular collection. All features of the same collection must have the same attributes, but features of different collections do not need to share specific attributes unlike general ones. For instance a _"wind"_ collection can have the _"east"_ and _"west"_ attributes to describe the wind vector components.