Lucid Player v4

Lucid Player Pruning the Feature tree – The Prune Redundants function

After a number of Features have been chosen and the Entities Remaining list has been substantially reduced, some Features and States may be redundant for the identification.

A state is considered redundant if it applies to none of the Entities remaining, or to all of the Entities remaining (choosing such a State will either leave no entities or remove no Entities, so it is ineffectual to answer). A Feature is redundant if all of its States are redundant.

The Prune Redundants function will scan the Features in Features Available and remove any redundant Features and/or states for the remaining Entities. This may be useful to “clean up” the list of Features, to make it less likely that a choice will be ineffectual.


There is one circumstance in which apparently redundant states may be left in after pruning. Consider a two State Feature, one State of which would remove some remaining taxa, the other of which would remove none. The State that removes no taxa is not logically redundant in this case, and would not be removed since removing it would leave a character with only one State.

To activate the Prune Redundants function, choose Prune Redundants button Prune Redundants icon on the toolbar.

Prune Redundants can be automated, so that it is recalculated after each feature is addressed. Choose the option Automate>Auto Prune from key settings page, if available.


If you need to choose several States from one feature when Auto-Prune is on, hold down the Control key when choosing the States – Auto-Prune will be paused until the Control key is released.

Lucid Player v4

Lucid Player – Finding the Best Feature – The Best Function

Once one or more States have been chosen and the list of Entities Remaining has been reduced, some Features may be more useful for the next step in the identification process than others. For example, some Features may be scored the same for all Entities Remaining, in which case choosing a state of that Feature would not contribute to the identification.

Lucid has a Best algorithm for determining which is the best Feature to address at any stage during an identification session. In general, a Feature that would, on average, cause the list of Entities Remaining to be halved is a good Feature to address.

Find Best will determine which is the best feature to address next, and jump to and open that Feature in Features Available.

Find the best feature to address next by clicking the Best button Best icon on the toolbar.

If the list of Entities in Entities Remaining changes after choosing a Feature as suggested by Best, it may be worth clicking the Best button again to recalculate the next best Feature to address.

Best can be automated, so that it is recalculated after each Feature is addressed. Choose the option Automate>Auto Best from the key settings page, if one has been provided.


If you need to choose several states from one feature when Auto Best is on, hold down the Control key when choosing the states – Auto Best will be paused until the Control key is released.

Lucid Player v4

Lucid Player Un-choosing and changing chosen States

Chosen states in Lucid are checked with a tick in both the Features Available and Features Chosen lists. To remove a previously chosen state, simply un-check its checkbox in either list. Note that unchecked states remain in Features Chosen until the key is restarted – this allows them to be easily re-chosen, if necessary.

To change the value of a chosen Numeric Feature, click on its edit box in Features Chosen then change the values entered in the Numerics dialog box. To un-choose the feature completely, remove any values from the dialog box and click OK.

Lucid Player - Unchoosing Feature States example
Lucid Player – Un-choosing Feature States example.

Un-selecting state can be done either via the Features Available panel or the Features Chosen Panel

Lucid Player v4

Lucid Player Choosing Numeric Features

For Numeric Features, you must enter a value rather than choose from a set of States. Length and width features, for example, may be treated in Lucid keys as numeric rather than multi-state Features.

Numeric Features are preceded by an edit box rather than a checkbox:

Lucid Player Numeric Feature dialog example
Lucid Player Numeric Feature dialog example.

To enter details about a Numeric Feature, click its edit box. A dialog box will pop up into which you can type the appropriate value.

You can enter single values and ranges. Valid entries will be of the form:

  • x (a single value)
  • x-y (between x and y)
  • <x (less than x)
  • >y (greater than y)

It’s good practice when using Numeric Features to enter a range rather than a single value if possible. For example, if a key to plants has a Feature Leaf length, it’s better to choose several typical leaves from your specimen and to enter the range of leaf lengths found over those leaves (ignoring unusually small or unusually large leaves) than to enter the length of a single leaf.

Also see Choosing States from multi-state Features.


The Lucid Player assumes an accuracy for numeric values based on the number of decimal places specified. For example, entering the value 10 (no decimal places) will be read by Lucid as meaning the range between 9.5 and 10.5; entering 10.5 will be read as the range between 10.45 and 10.55. Hence, if you enter the single value 10, an entity scored as having the value 9.6 will be regarded as a match.

Lucid Player v4

Lucid Player Choosing States from multistate Features

In Lucid, all states in Features Available are provided with checkboxes. Choose a state by clicking on its checkbox. Entities that match the chosen state will remain in Entities Remaining; entities that do not match will be moved to Entities Discarded. The chosen state will also be displayed within the Features Chosen list.


In Lucid keys, you may choose more than one state for any given feature (unless the key author has used a single selection feature type). For instance, if a key has a feature Flower colour with states white, cream, yellow, red, and blue, you may be unsure whether to choose the states white or cream for your specimen. In this case, choose both states. In normal identification mode, Entities Remaining will list all entities with white or cream flowers.

Lucid Player Flower Color Feature example
Lucid Player Flower Color Feature example.
Lucid Player v4

Lucid Player Finding Features, States and Entities

To search for a Feature or State, activate one of the Features panels (Features Available or Features Chosen (if visible)) by clicking within it or its header bar, then choose the search option find/search icon on the toolbar.

Lucid Player Entities Search Dialog
Lucid Player Entities Search Dialog.
Lucid Player Features Search Dialog
Lucid Player Features Search Dialog.

To search for an entity, activate one of the Entities panels by clicking within it or its header bar, then choose the search option find/search icon. on the toolbar.

Within the Search dialog, type the text to search for in the Find text box. Click the Find button to initiate the search. If Case sensitive option is checked, the search will be case-sensitive (that is, an item called Item will not be found if the search text is item). If the Whole word option is checked, the search will match only whole items (that is, an item called Item One will not be found if the search text is Item or One).

The Find function can also be invoked using the keyboard shortcut Ctrl+F or the Findfind/search icon button on the main toolbar.


The browser also has a find text within the current web page option. Using this option will find text displayed on the page, however it won't find text within a closed feature or entity nodes as this data has not yet been loaded, where as the search option provided by the Lucid Player will.

Lucid Player v4

Lucid Player Expanding and Collapsing Tree Items

In Lucid keys, Features and Entities can be arranged in hierarchical trees. Where this is the case, nodes of the tree are opened and closed using buttons to the left of each node:

Alternatively, the Collapse All and Open All buttons on the toolbar Lucid expand tree icon Lucid collapse tree icon will collapse or open all child nodes at that level.


At start-up both the Features Remaining and Entity Remaining trees will be collapsed to its root branches.

Lucid Player v4

Lucid Player About Entities and Features

Entities in Lucid are the things the key aims to identify. Depending on the scope of the key, the entities may be different kinds of things. For example, in a key to the palms of Brazil, the entities will be species of palms, in a key to the families of flies of the world the entities will be fly families, in a key to minerals the entities will be types of minerals, in a key to disorders of sweet potatoes the entities will be the causes of disorders found in sweet potatoes. In Lucid we use the term entity because it applies to all the possible things that a key may be designed to help identify. Lucid itself doesn’t know whether the entities are species of plants, families of flies, minerals or diseases – they are all simply entities to Lucid, and are all handled in the same way.

Features in Lucid are characteristics of the entities in the key that can be used to describe each entity.

Lucid Player - Simple feature example
Lucid Player – Simple feature example.

For example, in a key to minerals one feature may be the types of crystalline form shown by the mineral. Amongst the minerals in the key, there will be a number of different crystal forms – cubic, tetragonal etc. The different possibilities for crystal form are called states of the feature. States of a feature are indicated in the Lucid Player by scoring boxes preceding the state names.

In Lucid there are three main types of features.

Lucid Three Types of Features
Lucid – Three Types of Features.

Multi-state features, like those shown for the crystal form of minerals, have two or more alternative states.

Numeric features, by contrast, are ones in which real numbers (integer or decimal) are used to describe the entities.  Numeric features are normally used for lengths, widths, ratios and counts. For example, a key to butterflies may use a numeric feature for the length of the forewing, or for the number of segments in the antennae.

Grouping features are features that contain other features.

Lucid Player v4

Lucid Player Opening a Key

Opening a key is just a matter of opening a HTML page in your favourite web browser. No additional software or installation is required. The web page will contain all the information required to load the Lucid Player and the key data. The key author may also have provided a setting page with the key that allows you to select various options for the key and the Player interface.

A Lucid key can be opened, depending on where it’s deployed, from a website, USB, CD/DVD Network Drive or Hard Drive. Again no matter the location of the key only your web browser is required – no installation of any kind is required.

Lucid Player v4

Using the Lucid Player

Lucid Player example key within the main interface
Lucid Player example key within the main interface.

The four main panels displays of features and entities:

Lucid Player Feature Available Panel
Lucid Player Feature Available Panel.
Lucid Player Feature Chosen Panel
Lucid Player Feature Chosen Panel.

Features Available shows the features and states in the key. An identification is performed by clicking on (and so ticking) score boxes next to those states that match the specimen being identified.

In some keys, features and their states will be illustrated by images displayed next to the feature or state name. See the topic Multimedia in the Lucid Player for more information.

Features Chosen shows the features and states that have been used to describe the specimen being identified.

When an identification is started this window will be empty; as features are progressively selected in Features Available, they are copied to Features Chosen for handy reference.

To unchoose a previously chosen state, click on (and so un-tick) its score box in Features Chosen.

Lucid Player Entities Remaining Panel
Lucid Player Entities Remaining Panel.
Lucid Player Entities Discarded Panel
Lucid Player Entities Discarded Panel.

Entities Remaining shows all entities that match the chosen features and states.

In some keys, entities will be illustrated by images and web pages displayed next to the entity name. In addition, a tab at the bottom of the Entities panels provides access to a gallery of images for all remaining entities. See the topic Multimedia in the Lucid Player for more information.

Entities Discarded shows all entities that do not match the chosen features and states.

The button bar and menu contains many options to help make an identification easier. See the topic The Lucid Player’s Menu and Button Bar for links to help on these.