next up previous contents index
Next: XML element names for Up: Root-element Previous: Optional part   Contents   Index


Domains

The element for the domains element has the name domains and consists of a domain list.

The domain for values element has the name valueDomains and has the same structure as the domain element with the name domains. This element (valueDomains) has no effect when saving in XML format, but is for keeping the information.

The domain list identifies the domains of each element, if a value (e.g. a variable) is outside its domain, it is rounded to a value within the domain. Values outside these domains can thus not occur for the element.

The domains for values include also domains, but these domains only apply to actual values in elements and not for values of contained variables. The domains for values determine how many bits are needed for compressed storing (see section 21 on page [*]) of an element that contains a value. The domains for values are useful when the values of an element do not cover the full possible range of the domain for the element. For example, if a subobject contains only points whose position vectors only contain variables and integer values between 0 and 10, the domain for values for position vectors can be set to "integerB" with 4 bits, even if the variables of the position vectors taking values greater 100 .

The reason for the introduction of central (in the root-elements) domains is, that on the one hand as little space for values should be used when compressed storing the Fib object, without drastically limit the assignment possibilities for the values and on other hand that it can be determined in advance if and how the multimedia object can be displayed (e.g. if and how it should be scaled or whether the display of all values is impossible). If for example, the domain for the dimension takes only integer values between 0 and 50 (e.g. the horizontal in an image), then 6 bits is enough to store the values for the dimension. For larger images simply more bits for the values of the dimension can be used.


Each of the two domain lists contains a number of domain entries. A domain entry is an XML element for the type of Fib element for which it applies. This XML element in turn contains the actual domain.



Subsections
next up previous contents index
Next: XML element names for Up: Root-element Previous: Optional part   Contents   Index
Betti Österholz 2013-02-13