ACQUISITION AND REPRODUCTION OF SURFACE APPEARANCE IN ARCHITECTURAL ORTHOIMAGES
Software tools for photogrametric and multi-view stereo reconstruction are nowadays of generalized use in the digitization of architectural cultural heritage. Together with laser scanners, these are well established methods to digitize the three-dimensional geometric properties of real objects. Howe...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-02-01
|
| Series: | The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences |
| Online Access: | http://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XL-5-W4/139/2015/isprsarchives-XL-5-W4-139-2015.pdf |
| Summary: | Software tools for photogrametric and multi-view stereo reconstruction are nowadays of generalized use in the digitization of architectural
cultural heritage. Together with laser scanners, these are well established methods to digitize the three-dimensional geometric
properties of real objects. However, the acquired photographic colour mapping of the resulting point clouds or the textured mesh cannot
differentiate the proper surface appearance from the influence of the particular illumination present at the moment of the digitization.
Acquisition of the actual <i>surface appearance</i>, separated from the existing illumination, is still a challenge for any kind of cultural
heritage item, but very specially for architectural elements. Methods based on systematic sampling with commuting light patterns
in a laboratory set-up are not suitable. Immovable and outdoor items are normally limited to the existing and uncontrolled natural
illumination.
<br><br>
This paper demonstrates a practical methodology for appearance acquisition, previously introduced in (Martos and Ruiz, 2013), applied
here specifically for the production of re-illuminable architectural orthoimages. It is suitable for outdoor environments, where the
illumination is variable and uncontrolled. In fact, naturally occurring changes in light among different images along the day are actually
desired and exploited, producing an enhanced multi-layer dynamic texture that is not limited to a frozen RGB colour map. These layers
contain valuable complementary information about the depth of the geometry, surface normal fine details and other illuminationdependent
parameters, such as direct and indirect light and projected self-shadows, allowing an enhanced and re-illuminable ortoimage
representation. |
|---|---|
| ISSN: | 1682-1750 2194-9034 |