Method for analyzing, documenting and restoring decorations on plasterwork

Abstract: Method for analyzing, documenting and possibly restoring decorations on plasterwork, especially paint work or ornamental reliefs, The method comprises the following steps: a) determining the colour and location of each part of the respective decoration on a suitable carrier; b) determining at least one dimension of at least one part of the decoration, which dimension may be used as reference; c) digitizing the data obtained in step a); d) analyzing with help of computers, functioning with suitable analyzing software, the digitized data to reconstruct, especially in case of damaged decorations, the colour and shape of the original decoration as accurately as possible; e)storing the obtained data of the decorations, reconstructed in this manner, in a suitable memory means. Thereafter templates or moulds are made with help of the memorized data concerning the reconstructed decorationsand these templates or moulds are used to reconstruct therewith the original paintwork or ornamental reliefs.

Description: The invention relates to a method for repairing, restoring and/or reconstructing the colour and/or shape of plasterwork, especially paint work thereon or ornamental reliefs thereof. The skilful restoration of paintings or ornamental reliefs on plasterwork depends largely on the skill and artistic capabilities of the restorer. The restoration of decorations of this tyke is therefore very time-consuming and therewith in general a costly operation. Especially in case of large buildings where the decorations could cover many hundreds of meters, as is often the case in churches, palaces and large public buildings, the costs of a complete plasterwork restoration could be very significant. Often, these costs form such a barrier that restoration is abandoned and another solution is selected whereby not seldomly the original decorations are lost forever. Object of the invention is now in the first place to prevent, even if for the time being or on a more permanent basis another solution then restoring the original decorations is selected, that the information about these original decorations will become lost. In other words, the object of the invention is to take care that the information about the decoration is maintained as good as possible, especially in such a manner that it will be possible to reconstruct the decoration. A further object of the invention is to indicate how the restoration of decorations can be performed efficiently in such a manner that there is no or hardly any difference between the reconstructed restored decoration and the original decoration, whereas on the other hand the reconstruction and restoration will require less time than was necessary in the past. In agreement with these objects the invention provides now a method for repairing, restoring and/or reconstructing damaged plasterwork, especially paint work thereon or ornamental reliefs thereof, comprising the following steps: a) determining the present colour(s) and /or shape of the plasterwork and storing the obtained information in a suitable manner, b) determining at least one dimension of at least one part of a paintwork decoration an/or an ornamental relief, which dimension may be used as reference; c) digitizing the data obtained in step a) and b); d) analysing the digitized set of data with help of computers, functioning with suitable analysing software, to model the original plasterwork as accurately as possible, and to obtain a new set of data representing the colour and/or shape of the original plasterwork; e) storing the obtained new set of data in a suitable manner, f) manufacturing templates and/or moulds using numerical controlled manufacturing apparatuses controlled by the data stored in step e) g) restoring or reconstructing the colour(s) and/or shape of the plasterwork using the templates and/or moulds resulting from step f). If it is the object for the time being to only collect and store the information (at least temporarily) about the original decorations as good as possible, than it is sufficient to carry out only the steps a) an b). The further steps c)...e) can be carried out at any later date if convenient and the actual reconstruction phase represented by steps f) and g) can be carried out even later. The attention is drawn to the fact that methods as such for collecting data about art work, sculptures etc using various different techniques are known to the expert in this field. Examples of the application of such methods are described in an article "Art analysis: probing beneath the image" by Karen Freifeld, published in IEEE Spectrum, vol.23, no. 6, 30 june 1986, pages 66-71. Another article devoted to the same project is "Digital image processing in art conservation" by J.F. Asmus, published in Byte, vol. 12, no. 3, march 1987, pages 151-165. In both articles only method steps are described which fall within the scope of one or more of the steps a)...e) of the above identified method with the restriction that the application of such methods for paintwork on plaster and for ornamental reliefs on plaster is not mentioned or even suggested in these articles. The invention will be explained in more detail with reference to the attached drawings. Figure 1 illustrates in a flow diagram the various steps which have to be carried out in the method according to the invention to store information about a decoration in such a manner that said information can be used at a later date for a possible reconstruction or restoration. Figure 2 illustrates the application of the method according to the invention especially for storing data about ornamental reliefs on plasterwork. Figure 3 illustrates the steps which are necessary to reach a complete restoration especially of paintwork, using the relevant stored data. Figure 4 illustrates the steps which are necessary to reach a complete restoration of especially ornamental reliefs, using the relevant stored data. In the first step 10 in the flow diagram of figure 1 information about the decoration in its pending status is recorded on photo, film or video. More especially one or more pictures of the respective decoration are taken with a photocamera, whereby preferably colour photographs or colour slides are used to register not only positional data, but also the necessary colour data. As alternative one could use a film camera or a videocamera, but practice has proven that especially colour photo's or colour slides provide the best information, especially if a fine-grained film is used. Besides taking pictures, films or video images of the decoration, one or more parts of the decoration are measured such that afterwards one has available at least one or more reference dimensions on the basis of which during a later restoration or reconstruction the dimensions of the decoration as a whole can be checked. The obtained images of the decoration are digitized in step 12. For that purpose a generally known colour scanner can be used for scanning the colour photos or colour slides. During the scanning process such a scanner supplies at its output a series of pixel data, especially data concerning the colour and position of each pixel. These pixel data can be stored in a computer readable memory. Said last action is carried out in step 13 in figure 1. Thereafter in step 14 the pixel data of the decoration, obtained in this way, are analyzed. For that purpose especially mathematical software is used with help of which a complete continuous line can be reconstructed even if only one or more parts of this line are known. It is proven that such software is able to restore the contours of a decoration completely on the condition that sufficient parts of the respective contours are known. Suitable programmes are known as such and are for instance used in the graphical industry. The attention is pointed to programmes as "Dido Line Art", "Calamus SL" en "Avant Vektor". The output of step 14 is a collection of data relating to the reconstructed decoration. These data are in step 15 stored in a computer readable format. Possibly these data can be used to print an image on paper, for instance for documentation purposes. It is not only possible to use photos, films or video images for describing the necessary data of a decoration in its pending status, also depth scanners can be applied especially for ornamental reliefs in plasterwork. Such depth scanners are known as such for instance embodied as laser scanners, ultra sound scanners or UV-scanners. In that case the embodiment of the method as illustrated in figure 2 will be applied. In step 20 of figure 2 the ornamental relief is scanned using a depth scanner. The ornamental relief is for instance scanned linewise, whereby of each pixel of a line both the position of the pixel as well as the distance to the source of radiation is registered. Based on these data it is possible to form a three-dimensional image of said relief. That is done in step 21, in which the collection of data gathered in step 20, is converted into three-dimensional digital data using suitable software. These three-dimensional digital data are analyzed in step 22 using further suitable software, which is known as such. In a similar manner as indicated in the embodiment illustrated in figure 1 missing parts of the relief can be reconstructed based on those parts which are still present. For that purpose again use is made of mathematical programmes, which are known as such and which are able to reconstruct a complete contour based on a relatively minor number of data. At the end of the process, carried out in step 22, the three-dimensional data of the reconstructed ornamental relief are available. These data are stored in step 24 such that they can be used afterwards for a possible reconstruction or for restoration purposes. As is illustrated in the flow diagram of figure 3 during the restoration or reconstruction of a painting or plasterwork according to the invention the data, which are stored in step 15 of figure 1, are retrieved from the memory in step 30 and are used for controlling a template-cutting machine in step 31. Such template-cutting machines are known and are for instance applied in the confection industry, where such machines are used for cutting into shape the textiles of which thereafter clothing can be manufactured. Also in other areas these template-cutting machines are used, such as in the commercial and advertisement industry. Based on the data, collected in step 15, templates are cut out, preferably from adhesive foil. For each colour of the painting a separate template is prepared. In step 32 these templates are attached to the plasterwork, which if necessary is repaired and restored, at the location where the painting has to be reconstructed, and thereafter the painting is restored or reconstructed using these templates. Thereby each template is attached in its correct position and by using suitable tools each time a paint of the correct colour is applied on the plasterwork within the template openings. After the colours for each template are applied and the last template is removed from the plasterwork the original decoration is restored or reconstructed. In case the invention is applied for reconstructing ornamental reliefs on plasterwork, then the data resulting at the end of step 24 can be used for preparing a mould. For that purpose various controllable tools can be used. In a preferred embodiment of the method, illustrated in the flow diagram of figure 4, a milling machine is used controlled by the data obtained at the end of step 24. For that purpose first of all the necessary data are retrieved in step 40 from the memory, in which they were stored at the end of step 24. Based on these data in step 41 the milling paths, which have to be followed by the milling machine to obtain a mould from a suitable piece of material, are calculated. Under control of these path data thereafter the milling machine is used in step 43 to prepare the mould. The mould is made with help of the milling machine in the shape of the respective ornamental relief from a suitable material such as wood, synthetic material or another material. If necessary a manual finishing touch is carried out in step 44 whereby for instance the dimensions are checked using a depth scanner to see if any finishing touch is necessary. This step is optionally. With help of such a mould in step 44 a number of negative moulds can be made successively, for instance from rubber, which negative moulds can be used in turn for manufacturing the ultimate reconstructed ornamental reliefs in step 46. As an example the method according to the invention is applied in a church, especially a neogotic building dating from 1854 with beautiful plasterwork and many hundreds of meters of paintwork on the walls, on pilars, along ceiling ribs, etc. In the course of time the old plasterwork came loose at many places from the walls. These damages were repaired occasionally with plaster and painted white thereafter. A part of the paintwork especially the paintings which appeared in a repeating pattern, was therefor lost. Other parts of the paintings were damaged and therefore not completely available anymore. Initially a part of the paintings was restored in the "old" manner, i.e. was restored manually by various skilful plaster painters. This is a very labour intensive process which requires lots of skill, artificial sense and experience in restoration work and requires therefore high costs. At the time 20% of the restoration was done one adapted the method according to the invention. The still present original restorations were all photographed. All photos were scanned thereafter using a scanner and the scanned data were digitized and stored digitally in a suitable memory. Thereafter the digitized data were analyzed using suitable computer software, which as such is known and used in the graphical industry, whereby it appeared to be possible to reconstruct all contour lines, even if these lines were not, or not completely present or visible anymore in the decoration. It is also possible with such software to mirror or duplicate certain designs such that a repeating pattern of decorations can be obtained or such that decorations at one side of a central line can be mirrored to corresponding decorations at the other side of the central line. Such situations appear for instance in a ceiling which has ceiling ribs. Furthermore it appeared to be very well possible to determine the original colours with large degree of certainty. In the above-mentioned practical case the original decorations were 140 years old, but based on the discoloration and based on the present colour differences, it appeared to be very well possible to determine the original colour with large certainty. After mapping the still present decorations in this way, digitizing the obtained data and adding further data such that a complete collection of reconstructed decorations was digitally stored in the computer memory, this collection of data was used to control a cutting machine for cutting templates. These templates were attached to the plasterwork, which was repaired in the meantime, and used for applying the correct colour. As soon as the paint had dried sufficiently the template was removed and it appeared that the patterns, cut out of the template were accurately and in the correct colour visible on the supporting plaster. It appeared to be possible in this practical example to carry out the job, which would take with the "old" method more than three months, in about three weeks. Therewith ultimately a reduction in costs could be realized such that 80% of the job, carried out with the method according to the invention, did cost the same amount of money as the 20% of the job which was carried out initially using the old method.

Claims: Method for repairing, restoring, and/or reconstructing damaged plasterwork, especially paint work thereon and/or ornamental reliefs thereof, comprising the following steps: a) determining the present colour(s) and/or shape of the plasterwork and storing the obtained information in a suitable manner; b) determining at least one dimension of at least one part of a paintwork decoration and/or an ornamental relief, which dimension may be used as reference; c) digitizing the data obtained in step a) and b); d) analysing the digitized set of data with help of computers, functioning with suitable analysing software, to model the original plasterwork as accurately as possible, and to obtain a new set of data representing the colour and/or shape of the original plasterwork; e) storing the obtained new set of data in a suitable manner, f) manufacturing templates and/or moulds using numerical controlled manufacturing apparatuses controlled by the data stored in step e); g) restoring or reconstructing the colour(s) and/or shape of the plasterwork using the templates and/or moulds resulting from step f). Method according to claim 1, characterized in that the manufacturing of templates in step f) is carried out by controlling a flat web cutting machine with help of the data stored in step e) and related to the retrieved original decorations, to obtain templates, and that in step g) after eventually restoring the supporting plaster the templates are applied onto tie plaster and paint of a colour corresponding to the original colour is applied to reconstruct the paintwork as it was originally. Method according to claim 1, characterized in that the manufacturing of moulds in step f) is carried out by controlling a material shaping machine with help of the data stored in step e) and related to the retrieved original shape of the ornamental reliefs, and that in step g) the moulds are used to reconstruct the ornamental reliefs which, after eventually restoring the supporting plaster, are attached thereto to obtain the reconstructed plasterwork in the shape as it was originally. Method according to one of the preceding claims characterized in that , the present shape of the plasterwork, especially of the ornamental reliefs contained in said plasterwork, is done by scanning the respective ornamental reliefs using a laser beam, whereby continuously the position of each scanned point in the three dimensional space with reference to the laser source is determined and registered.

Inventors: BLEYENBERG TEUNIS, BLEYENBERG, TEUNIS
Applicants: RESCURA BV, RESCURA B.V.
Application year: 1993
Main classification: B44D7
IPC codes: B44D7