Lucid Builder FAQs

Lucid Builder Frequently Asked Questions

Lucid Builder

Can I create a dichotomous key with Lucid?

Yes, with the release of Lucid version 4.1, support for dichotomous (pathway) key construction is now supported.

Lucid v4 Builder also has a sophisticated text based dichotomous key importer that can check for errors prior to import. Multimedia can be easily added to your keys and then deployed with the no-install instant “play” Lucid Player. For more information on the Lucid Builder see:

To review specific dichotomous key features see the Lucid help.
To try out Lucid dichotomous and matrix keys visit:

Note: Construction of dichotomous keys was previously only available via Lucid Phoenix, which has now been discontinued.
Can I have my key hosted on Lucidcentral?

Yes, you can have your Lucid key hosted or listed on Lucidcentral at no cost (free).

To facilitate this, please provide us with the following:

  • Title of the key
  • Author(s) details
  • Brief description of the key – no more than one page
  • An image representing the key for the listing
  • Preferred key words for search index
  • Optional – Google Analytics tracking code
  • The key data, preferably in Builder format. This can be shared via a file service such as Dropbox or WeTransfer etc. (Zip the key data and share the download link).

Once the key has been lodged we will give you the URL for your key. You will have the opportunity to check over the listing prior to it being publicly listed.

Please submit these details via a new Support Ticket in the ‘My Account‘ dashboard.

Can I view keys without a web server?

Yes, the Lucid Player can run from a Hard Drive, USB, CD\DVD or a web server. If the key has been deployed via the Lucid Mobile Platform, then it can also run from Android and iOS devices.

Note: If a key author has posted a key via their web server, not as a downloadable file, then the key is set to run from the website. That is it won’t run off your hard drive or run while you don’t have an internet connection.

The key author may have also connected some or all of the keys media to a website(s), even though it maybe running from your hard hard, for example. In this case the key will operate from the hard drive without an internet connection, but the Internet based media will fail to load if you don’t have an Internet connection. If in doubt consult the key author on their keys configuration and requirements.

Distributing keys

How to send your keys to others

As a key author you can either send your Builder formatted key to other collaborators; Or distribute your finished key to a website or colleagues. Below outlines what you need to package up for sending.

For either key format (compiled or uncompiled) we recommend Zipping the files into a single archive for ease of sharing the file either via a file sharing service or email, if small enough.

  1. Builder format (editable key – uncompiled)

Zip archive the following two items:

<key name>.lk4
<key name folder>

  1. Deployed key (Web deployed (non-editable – compiled) – highly recommended as the end user requires no additional supporting software to use the key other than their web browser.)

Zip archive the following items, if sending to an individual. If posting to a website do not zip:

<key deployment name>.html        <— Filename set via the deployment dialog (key title)
key                                                    <— Key folder
player                                                <— Lucid Player folder

Do you offer a discount for students?

Yes, we now offer a 40% discount for students.

To qualify you must currently be studying at a recognised educational institution and have a valid educational based email address.

Please note: Student licences are non-transferable and non-upgradeable.

Use coupon code: Student40


Does Lucid run on a Macintosh (OSX)?

Yes. See the System requirements FAQ for more details.

Manual registration and activation procedure

Lucid Builder registration dialog

Manual registration and activation procedure

If for any reason the automatic activation of Lucid fails, the following outlines the manual activation procedure:

  1. Ensure you have filled out the registration dialog with the same details as your licence. I.e. Same name, email address and serial number.
  2. When attempting to activate your licence will create a registration file. This file can be sent to the Lucid support staff who can manually activate your licence. The registration file can be found:

    Windows: C:\users\<your username>\.lucid\

    OSX/Linux: <your home folder>\.lucid\

    Lucid v4 the registration file will be called ‘LucidBuilder4.registration‘; Lucid v3.x the file is named ‘Lucid_Builder.registration‘.

  3. Email this file, along with any error details you received when the automatic activation attempt failed, to [email protected].
Resetting activation’s

Question: Can I have my licence moved to another computer, if it crashes or I upgrade?

Answer: Yes, just lodge a support ticket at the help desk and we will reset your activation. This will allow you to re-activate again. There is no cost for this.

Trouble shooting issues with Lucid Builder

Having problems with Lucid Builder? Please check over these common causes.

1. Lucid Builder running slowly or the save and open operations are very slow.
A Virus or Malware scanner may be constantly checking the file and data operations of Lucid or the Java Runtime Environment (JRE).
Solution: Add Lucid’s executable (Windows) or JAR file (OSX/Linux) and the Lucid install folder to the scanners exceptions list. Please refer to your virus scanners help on how to do this.

2. Lucid Builder or the Lucid setup package doesn’t open.
Normally this is a Java Runtime Environment (JRE) problem – I.e., not installed, out of date, memory allocation restrictions or the JRE isn’t in the operating system environment path.

Solution: Update the to latest available JRE, free from: During the install ensure you elect to add the JRE to the system path. Check that you have enough available system memory to run Lucid, particularly if you are running a large number of other apps at the same time. Lucid’s memory requirements are generally quite small, though very large keys and keys with large media sets will require additional memory to process.
Note: To install Lucid, you need administrative rights on your computer. Please see your IT support for assistance, if your account doesn’t have this level of access.

3. Working directly on a cloud synchronised folder, network drive or an older USB stick drive.
Some cloud sync services can greatly slow and even interfere with file operations. Network drives can also be affected by network congestion and slow speeds. Older USB stick drives can be very slow and/or unreliable.

Solution: Try moving the key to another non-cloud/network drive based folder to see if this makes a difference.

4. The hard drive is failing or running out of space.

Solution: Check the hard drive health and available space, including the operating system drive. Try saving and constructing the key on a different drive.

5. Corrupt images within the key.
Lucid is often checking, loading and thumbnailing images held within the key. If one or more images are corrupt, it can greatly slow down these operations.

Solution: Determining problematic images can be difficult. Look for any images that are only partly ‘rendered’ or no thumbnail is present, or the thumbnail is all black or all white. This may indicate the larger image is corrupt. Another alternative is to batch process the images to optimise the file, via a third party graphics package (E.g., IrfanView or Photoshop or GIMP). Enabling logging within Lucid (see below) may also indicate problematic images in the log output.

6. Very large images – Lots of very large images (e.g. 5MB or greater) can be slow to process (for any application).

Solution: Normally such high quality/large images are not required (and are undesirable if the key is to be web based). Try optimising them (dimensions and file size) with a third-party graphics package (E.g., IrfanView or Photoshop or GIMP). We normally recommend the JPEG format, or PNG format, if background transparency is required. If the key is going to be deployed on the web, for the best end user experience we would recommend a longest side image dimension of no more than 1200px, targeting a file size less than 500kb. Ideally the file size would be less than 300kb.

Finally check that your Lucid Builder is up to date. See the update notification URL for the latest release information:

If none of the above has helped, check your operating system processes to examine CPU and hard drive consumption for Lucid (e.g. while saving etc) and other applications. (e.g., Task Manager). Is it excessive on one or more processes? If so, try closing the offending application.

Enable the logging feature in the Lucid Builder:

To enable logging do the following:

  1. Copy the ‘log4j.xml’ file from the Lucid install folder ‘resource’. I.e., ‘C:\Program Files\Lucid4\resource\log4j.xml’ to the root install folder. i.e., ‘C:\Program Files\Lucid4\’
  2. Next, edit the copied ‘log4j.xml’ file in a text editor such as Notepad++ (not MS Word).
  3. Look for a property named ‘basePath’ and edit the path to a location Lucid can write out a log file. The path/folder must exist and not be a restricted system location. Note the forward slashes, use these instead of back slashes regardless of operating system.

Next, run the Lucid Builder as usual – try saving and deploying etc. You should now see a file has been created in the base path location called ‘Lucid.log’.

Please send Lucid support this file (zipped), along with any other relevant information about your key and operating system for us to investigate further.

What are the system requirements for Lucid?

Lucid Builder

The Lucid Builder requires the Java Runtime Environment (JRE) to work.

Java enables the Lucid Builder to run on any operating system that’s supports the JRE. E.g. Windows, OSX, Linux and Solaris.

There are two JRE’s to choose from:

Lucid requires very little memory and hard disk space, though your key data may require more!

  • Hard drive space: 75MB
  • RAM: 128MB

The actual space taken up may vary slightly depending on operating system and installed options.

If you need more specifics on supported operating systems, please check the preferred JRE website (as shown above) for their system requirements.

Lucid Player (JavaScript Edition)

Any modern web browser that supports JavaScript (all the major browsers do!). For example:

  • Chrome
  • Firefox
  • Safari
  • Edge

Note: Support is excluded for Internet Explorer, even though it should work (>= v8). If you are forced to use a Microsoft based browser, use Edge.

Lucid Mobile

The Lucid Mobile Platform offers both Android and iOS native applications.

The minimum operating system requirements for your device are:


iOS (Apple)

Where do I get support for Lucid?

If you have a question about a product submit a support ticket via the ‘MY ACCOUNT’ page. Or if you need help or think you’ve found a problem with your product first check:

  1. That you have the latest Java Runtime Environment installed. See the System Requirements for more details on obtaining the Java Runtime Environment. and;
  2. That you have the latest software build available for your licence. We are always improving the software to keep it up to date with operating systems and to stamp out any bugs.

If after checking you’re up to date and you still are experiencing an issue, submit a support ticket via the ‘MY ACCOUNT’ page.

We normally try and respond to all support requests within one business day.

If you are experiencing a problem with a key hosted on website outside the scope of, please if possible, contact the site owner first.