metria: digital photogrammetry for architecture, heritage, engineering and industry

King's Chapel presents a hexagonal shape in its gothic vault structure but with a Renaissance and baroque decoration. On the right side we find a door that get in touch with the vestry. The XVI century altarpiece, dedicated to San Pedro, is gilded and polychrome. On the top there is an image of the Virgin with the child Jesus upon her knees, work of Juan de Balmaseda. The chapel can be locked with bars, work of Francisco Martinez, gilded and polychrome with a series of medallions with faces of the Kings.

The work to accomplish had to accurately document the current-state of the chapel, maximizing the detail in the proposed representations. In this sense the elevation true orthophotos offer both characteristics, by means of orthogonal frontal reprojection of the images obtained in multiple oblique photographs. Therefore we produce a true orthophoto for each face and the vault, to a scale of 1:40. The approximate dimensions of the chapel faces are 5x15 meters. The chapel height made necessary the use of an elevating platform to gain access to the upper zones and leave no space without covering.

King's chapel true orthophotos. ARTEMON Técnicas de Arquitectura Monumental.
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In order to compensate the solar illumination effects we decided to cover with canvases the large windows from the outside, obtaining thus that the illumination mainly came from the inner artificial light. Several series of photographs were taken with three different illumination conditions (natural light, artificial light with spotlights and artificial light with synchronised flashes) with different illumination patterns to guarantee an acceptable aesthetic quality not only limited to the metric rigour.

Additionally the plans of all the vault faces and the vault floor were delineate, on the same scale, using the true orthophotos.

King's chapel plans. ARTEMON Técnicas de Arquitectura Monumental.
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A total station was used for the taking of control points that allowed to guarantee the measurement rigour and Cartesian axes definition for the project. For such an aim a free station methodology with measurements reiteration and fixed control points was used, in which a total reflection prism has been settled. For the other support points we made the station measurement without prism using targets and characteristic elements.

In this kind of projects it is very important to properly determinate the plumb line, therefore a laser level was used also for the horizontal plane determination to get redundant measurements allowing to fit the geometric model.