Measurements using the Structured Light Plethysmography method will be compared to those obtained by spirometry using a flow based pneumotachograph.~Spirometry is the gold standard for measuring lung function in both clinical support and research roles. Modern spirometers are high precision, reliable instruments enabling a large numbers of parameters relating to lung volumes and the rate of emptying the lungs during a forced expiration to be measured. The most common and accurate method to measure the patient's forced expiration is via pneumotachograph which measures the flow of air through a mouthpiece and integrates the signal to derive the volume expired.~Structured Light Plethysmography (SLP) system that measures changes of the chest and abdominal wall movement during breathing by modelling the thorax and abdominal surface defined by a projected structured light pattern which enables a grid of virtual parts to be formed, the movement of which is recorded by digital cameras. SLP provides non-contact assessment to provide lung function data utilising structured light technologies and enhanced imaging processing.~In this study direct comparison will be made of measurements recorded simultaneously using the two measuring devices in children and adults.~To examine repeatability of the agreement between tidal breathing parameters measured by two techniques, repeated measurements will be performed in each of a group of normal adult subjects. The investigators will also examine whether the agreement is affected by a change in tidal breathing parameters. To obtain a change in tidal breathing parameters, measurements will be recorded during resting spontaneous breathing and after a period of exercise to elevate Respiratory Rate.
Measurements of Structured Light Plethysmography (SLP) using a chest wall movement based method will be compared to those obtained by spirometry using a flow based pneumotachograph method. This study will enable validation of SLP in children and adults by allowing direct comparison of simultaneous measurements of breathing sequences using the two measurement techniques.~The investigators will also examine, in a group of normal adults, repeatability of the agreement between the two devices, and whether the agreement is affected by a change in tidal breathing parameters.