Laser scanning of St Trinitatis Church in Liepaja, Latvia
Mr. Jouko Pakkala, Seinäjoki Polytechnic, School of Information and Communication Technology and School of Culture and Design, Building Conservation
The church is being scanned from a few points from inside and outside. The reason of using several measurement points is that there would not be any shadow areas, where the scanner would not reach.
The Church of St Trinitatis in Liepaja is subsiding (sinking). The amount of subsidience will be measured during the future years. This means that some of the control points attached to the structure will have to be measured repeatedly.
When the church has been laser scanned, the post processing phase will begin. The point cloud will be transformed manually into a 3D model by using the 3D point cloud as control points.
After creating the 3D model the surfaces will be coated with textures. Textures are created from 2D photographs taken from the church.
Visualisation
The 3D model of the church will be visualized in the Virtual Reality environment (Cave) of Seinäjoki Polytechnic. The 3D model will also be available as a VRML file in web pages.
There is a lot of photographic material of the church available. The material was created by the School of Culture and Design of Seinäjoki Polytechnic during the restoration phase of the church by students of the degree programme of conservation.
3D modeling
In the first phase the 3D point cloud of the church is being constructed so that there are as few ”stray” 3D vertices as possible. When this phase is finished, new surfaces are being created using the 3D vertices as control points. Surfaces will give the building a correct shape. When the 3D model is finished, textures must be added to finish the process. Retouching textures is usually the most time consuming phase, which means that a lot of time should be reserved.
