Heritage house maintenance using 3D city model application domain extension approach

: Heritage house is part of the architectural heritage of Malaysia that highly valued. Many efforts by the Department of Heritage to preserve this heritage house such as monitoring the damage problems of heritage house. The damage problems of heritage house might be caused by wooden decay, roof leakage and exfoliation of wall. One of the initiatives for maintaining and documenting this heritage house is through Three-dimensional (3D) of technology. 3D city models are widely used now and much used by researchers for management and analysis. CityGML is a standard tool that usually used by researchers to exchange, storing and managing virtual 3D city models either geometric and semantic information. Moreover, it also represent multi-scale of 3D model in five level of details (LoDs) whereby each of level give a distinctive functions. The extension of CityGML was recently introduced and can be used for problems monitoring and the number of habitants of a house .


INTRODUCTION
The conservation and protection of the heritage of tangible and intangible forms has earned an ever-increasing and vibrant international attention since the 20th century (Vecco. M, 2010).Digital representations of architectural are increasingly used in cultural heritage and being an essential tool to facilitate further analysis related to urban or environmental issues (H.Richards-Rissetto and R. Plessing, 2015).Meanwhile, a detail representation of 3D city model is needed for some application such as heritage architecture, facility management and interior design (R. Akmaliaa et.al, 2014).The measurement tools that has the ability to generate the 3D model of building with fast and accurate with many method such as digital photogrammetry, laser scanning, Unmanned Aerial Vehicle (UAV) and others surveying techniqus (Basir.A et.al, 2014).The figures below show the 3D model result by using 3D software.

METHODOLOGY
Based on figure 5, there are many methods available for data collection.3D data such as Aerial Photo, TLS, Close Range Photogrammetry and Architectural Plan.I. Nazrita et.al, ( 2009) said among all these technique, digital 3D laser scanning method has proved to produced.Researchers may make data processing base on data obtained.This process usually take a time to get the proper and quality modeling.Lately, CityGML always used to solve the problem in term of management and technical.CityGML also use in maintaining and preserve heritage site.

LEVEL OF DETAILS (LODS)
Researchers are trying to develop efficient and effective method to create 3D model but each methods has advantages and limitation (Surendra Pal Singh et.al, 2013).All the data must be process according to their respective methods, for example data collected using TLS will be processed using Smart Scan or Cyclone 7.3 that produce point cloud data and then converted into 3D software such as AutoCAD, Revit, Sketchup, and another 3D software.Then, the 3D model will be exchange.
The 3D models was converted into GML files for represent in any of an open source software such as LandXplorer.The layer were created as the attribute to give semantic information follow the CityGML file structure.Furthermore, LoD0 refer to building footprint, roof outline and 2.5D digital terrain model which is lower detail of model and useful for mapping and landscape planning.The highest LoD4 visualize the interior of building and more detail structure displayed.As example for refurbish heritage house, the high resolution textured 3D model need to use to check wood decay due to temites.Or introduces interior heritage house for tourism purpose to tourisst in which use the LoD4.

EXTENDING CITYGML
CityGML ADEs has to be defined within an extra XML schema definition file with its own namespace.The advantage of this approach is that the extension is formally specified.The ADE concept support two different methods which are the existing CityGML classes can be extended through additional attributes and in ADE schema, new classes can be derived from existing CityGML using generalization concept (Romain Nouvel et.al, 2015).Thus, the ADE can use for any management such as Noise ADE, Energy ADE, Solar ADE and also Heritage ADE.According to J. Finat et. al (2010), they create CityGML framework by adding three task to support the software application (GIRAPIM) for heritage and urban documentation.

CONCLUSION
3D city model is a method to be real environment change to virtual 3D environment and can solve any problem in heritage preservation.By implement of LoDs, the 3D city model can be partition in different scale to analysis and management purpose.Meanwhile, CityGML have give beneficial for researchers to create 3D city model for its supported file.The ADE from CityGML extend have give advantages for semantically modelling detailed heritage house and the attributes that will be interoperable among many software application.