Visualiser and Document Cameras Guide

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Visualisers are also known as document cameras or visual presenters. They are the new modern version of overhead projectors (OHPs).

What are visualisers?

Visualisers are basically cameras mounted on an arm or gooseneck arm used to show in real time, using a projector, monitor or television, a 2D or 3D object to an audience.
They can also easily be connected to computers to capture images and interactive whiteboards for interactive presentations.

Their ease of use and versatility makes them a very popular tool in education where they help capture the attention of pupils during lessons. They are also very useful in scientific and technical applications.

To see a list of available visualisers and document cameras click here.

What can I do with a document camera?

There are many applications for document cameras. For example:

You can show a 2D object such as text in a book, a music sheet, photos and pictures to illustrate a lesson or plans and diagrams for a sales or technical presentation.
You can show 3D objects such as prototypes, models, plants or even an animal during dissection, etc.
You can show moving objects in real time (e.g chemical reaction, live animal)
Using a visualiser with a microscope adapter you can show microscope slides to a big audience.
Visualisers with a light box enable you to show acetate sheets just like an overhead projector.
When connected to a computer, the images can be captured and saved for later use.
When used with an interactive whiteboard you can create a completly interactive and attention grabbing lesson or presentation that can be annotated and saved.

What other equipment do I need?

The document camera is, as the name suggests, a camera, so you will need a separate projector or monitor / television to display what the camera sees.

This would be the minimum requirements but, as mentioned earlier, you can use the visualisers with interactive whiteboards, microscopes, computers etc. to enhance a lesson or presentation.

How to choose a visualiser?

With a wide range of visualisers available, how do you know which one is best?
It all depends on your application and requirements. Below we will explain the different features available on document cameras to help you choose a visualiser adapted to your application.

Main Features

Arm		The arm is the support holding the camera above the object. There are two types: rigid and gooseneck. The rigid arm, as the word suggests, is rigid and cannot be moved to any position although some models are telescopic and/or can be moved to certain angles. The gooseneck arm is flexible meaning you can place the camera anywhere around the object giving you more options.

Light Box / Lighting		A light box is a base with integrated lighting used to illuminate the object from underneath. In the same way as with an overhead projector, it can be used for showing acetates sheets. Not all visualisers come as standard with a light box. For some models it is an optional accessory while some others don't have the option at all. Alternatively (and sometimes additionally), some visualisers feature upper lighting. These lights illuminate the object from above and/or the sides to eliminate shadows or enable use in a darkened room.

Work Area		The work area is the area that the camera can pick up. So for example a visualiser with a maximum work area of 420x297mm can see a whole A3 size page without having to move it around. A large work area can be advantageous if for example you are showing plans or maps.

Resolution		The resolution is the number of pixels that make up an image - e.g. 800 x 600 means the picture is made of 800 columns of pixels by 600 rows of pixels; for a total of 480.000 (800x600) pixels making up the whole image. The larger the number of pixels the higher the resolution and the sharper and more detailed the image is. With visualisers, the most common resolutions found are XGA (good), SXGA (better)and UXGA (best).

Frame Rate		The frame rate is the number of images taken per second. The higher the frame rate the smoother the video and the less 'jumpy' it looks. High end visualisers usually have a rate of around 30 frames per second.

Inputs/Outputs		Most projectors will feature a VGA connection to connect to a projector, a Composite video connection to connect to a TV or monitor and a USB connection to communicate with a computer or interactive whiteboard. Some models will offer DVI or even HDMI connections for high definition pictures or network and RS232 connection for control. When choosing a visualiser make sure that it has the connections required for your application.

Built in Storage / SD Card Slot		Some visualisers have built in storage for saving images while some model have a slot for an SD card in addition or instead of built in storage.

WiFi / LAN		WiFi visualisers are starting to appear. They allow for greater portability although there are some concerns about video frame rates. Direct network connection is also possible on some high-end models.

Mounting		The majority of models are free standing to be used on a table or desk but there are ceiling mounted models that ensure uninterrupted line of sight between speaker and audience. Objects can easily be moved around the whole table or lectern underneath.

Dimensions / Weight		The dimensions and weight can be an important factor: - portable visualisers are the most common. They are ideal in limited space or as a shared resource. Generally less powerful than a larger platform visualiser, they are often more practical. - platform visualisers are larger and designed to be a permanent feature in a science lab, lecture hall, etc. They offer maximum optical zoom levels and high resolution/image quality (up to 1080p or full HD).

Other Features

Remote Control		Some visualisers come with a remote control. This allows the user to move around the room and still be able to control the visualiser.

Zoom		As with any camera the optical zoom use the lens to zoom in while the digital zoom uses a digital process to enlarge what the lens sees. The optical zoom gives a higher quality image but high optical zoom lenses are more expensive hence why digital zoom is also used. Most visualisers offer both optical and digital zoom for the best of both world. The zoom power is expressed in the format '4x' for example which means it can magnify the image by a ratio of 4. Generally the higher the optical zoom the better.

Auto Focus		The auto focus features ensures that the object being viewed is automatically in focus and remains sharp without needing manual adjustment.

Auto Brightness / Auto Iris / Auto Exposure		This feature controls the amount of light picked up by the camera as it automatically adjusts to changing level of room brightness.

Microscope Mode		This mode allows you to use the visualiser with a microscope. Some visualisers also come with microscope adapters.

Image Freeze		This feature allows the presenter to freeze the image at any point and remove or change the object under the camera without the image being displayed on the projector changing.

Image Flip / Rotation		This feature allows the presenter to rotate to projected image without having to move the object itself.

Split Screen / Picture in Picture / Slideshow		These features are for image comparison so you can compare a saved image(s) to the current image side by side or in a slideshow.

Other Image Settings		There are other image settings available such as gamma correction, white balance, negative and different modes to adjust the image being projected to ensure it is optimised or to add effects. Most visualisers will have these features but if you need a particular image effect for your application it is better to check.

Software		Different manufacturers offer different software with their visualisers and it is important to make sure the software available will allow you to do what you want.

What do I get for the money?

Visualisers vary greatly in price but here is a quick guide on how much you should expect to pay for different levels:

Entry level visualisers (£300 – £500)
- Lower levels of optical or digital zoom
- Manual/auto focus
- USB 2.0 connectivity for interactive whiteboard integration
- VGA connectivity
Mid-level visualisers (£500 – £700)
- Ability to capture images/video to different storage options, e.g. USB flash drive, SD card, internal memory
- Mid-levels of zoom (5x optical)
- USB connectivity for interactive whiteboard integration
- Auto-focus
High-end visualisers (£700+)
- High levels of optical zoom (15x +)
- Ability to capture images/video to different storage options e.g. USB flash drive, SD card, internal memory
- USB 2.0 connectivity for interactive whiteboard integration
- Auto focus
- Highest image quality (up to 1080p or full HD)