In many ways, canopies reach their full artistic expression in stained glass windows. There are no longer considerations about the practical building or manufacture of the canopy – it can just soar above the saint in splendid magnificence. They were also useful in that, since they were often painted in a light colour, they allowed extra light into the church.
Canopies in early panels, such as that of the Prophet Jeremiah, from the Abbey of St. Denis near Paris and dating to the 1140s, are relatively simple affairs with no perspective.
It is interesting to compare the architecture of the time and region with the canopies shown in stained glass. The round arches and columns of the church at St Denis are echoed in the stained glass.
http://en.wikipedia.org/wiki/File:Saint-Denis_-_Basilique_-_Ext%C3%A9rieur_fa%C3%A7ade_ouest.JPG
By the time the Boppard panels are being designed, the canopies were getting spectacular, as can be seen in the Boppard standing saints and Virgin & Child panels, below.
Again, compare these with Cologne Cathedral, started in 1248, and still under construction when the windows at Boppard were being painted. The two details and other features of the façade are quite closely echoed in the glass.
Another Burrell Collection window on display, the Life of Christ, was bought by Sir William Burrell from the Hearst collection. This is a two-light window with four scenes from the life of Christ; the Nativity, Christ before Pilate, the Crucifixion and the Resurrection, with the two upper scenes placed under wonderfully shaped canopies. This was made in France in the 1st half of the 15th Century, as the architectural styles which influenced the design were becoming increasingly complex.
Below is a detail of the highly ornate gothic decoration on the Church of Saint-Maclou in Rouen, begun in 1437 so of a similar date to the stained glass.
http://en.wikipedia.org/wiki/File:76-Rouen-St-Maclou-abside.jpg
Finally, two smaller panels showing the Virgin and St. John the Baptist, made in the Lake Constance area of South Germany around 1310, has splendid canopies. Originally part of a Last Judgment window, the two saints are interceding for the souls represented below them.
Boppard Conservation Project - Glasgow Museums 
