A computer implemented method of optimising a design of a component coated in a temperature indicating paint by conducting at least one analysis which incorporates empirically obtained data values indicative of a colour of the temperature indicating paint, the at least one analysis comprising the steps of: a) representing surface properties of said component as at least two 2D images defined by at least two 2D datasets which comprise a plurality of data values indicative of the colour of the temperature indicating paint, b) representing said component as a 3D computer model having a surface defined by a plurality of nodes, said nodes further defining a plurality of polygonal elements, c) by a user, defining at least six features common to both the at least two 2D images and the 3D computer model, d) by a user, identifying co-ordinates common to the at least two 2D data sets and the 3D computer model for the at least six features, e) assigning data values indicative of the colour of the temperature indicating paint from at least one common co-ordinate in the at least two 2D data sets to the associated nodal co-ordinate in the 3D computer model, f) resolving ambiguities between values from the at least two 2D data sets assigned to common nodes, said nodes defining polygonal elements common to both 2D data sets, by determining an apparent area of said common polygonal elements from each of the at least two 2D datasets which contain an ambiguous value, and using the data value from the 2D dataset associated with the common polygonal element having the greater apparent area, g) employing the 3D computer model in at least one analysis to optimise the design of the said component based on the assigned data values indicative of the colour of the temperature indicating paint, the method further comprising the step of selecting an optimum component design on the basis of the results of the at least one analysis. a) representing surface properties of said component as at least two 2D images defined by at least two 2D datasets which comprise a plurality of data values indicative of the colour of the temperature indicating paint, b) representing said component as a 3D computer model having a surface defined by a plurality of nodes, said nodes further defining a plurality of polygonal elements, c) by a user, defining at least six features common to both the at least two 2D images and the 3D computer model, d) by a user, identifying co-ordinates common to the at least two 2D data sets and the 3D computer model for the at least six features, e) assigning data values indicative of the colour of the temperature indicating paint from at least one common co-ordinate in the at least two 2D data sets to the associated nodal co-ordinate in the 3D computer model, f) resolving ambiguities between values from the at least two 2D data sets assigned to common nodes, said nodes defining polygonal elements common to both 2D data sets, by determining an apparent area of said common polygonal elements from each of the at least two 2D datasets which contain an ambiguous value, and using the data value from the 2D dataset associated with the common polygonal element having the greater apparent area, g) employing the 3D computer model in at least one analysis to optimise the design of the said component based on the assigned data values indicative of the colour of the temperature indicating paint,