Acquisition
The document surface is digitized by specially developed topography scanning techniques using a laser triangulation or confocal chromatic sensors, as well as infi nity focus which extends the depth of fi eld of microscopic images. Depending on the applied method, the height resolution changes from few nanometers to several micrometers.
Image processing
The functions of 3D image processing module include removal of surface artifacts, leveling, high-frequency fi ltering of paper fi ber fi lament and toner porosity, as well as low-frequency fi ltering of creases and furrows/grooves of the document. The implemented algorithms set the pattern of relief depth of writing trace and analysis of thickness of the ink layer.
Analysis and visualization
The 3D visualization module is based on the rendering and allows the superposition of a texture data on the actual image (optical 2D), false colors and contours. The user can select the data visualization color palette. The problem of controlling the observation point and location of the virtual light source in relation to document surface was solved. The mouse-stroke 3D surface manipulation is intuitive and ergonomic as in CAD software. The navigation panel allows easy location of the observation point.
